Solid State Guitar Amp Forum | DIY Guitar Amplifiers

figured i was starting too many threads and it would be better to keep it all in one place

gonna be posting some stuff that is painfully obvious to the more skilled members here yet is an epiphany for me  ::)

btw everybody here has been super cool and helpful

so here we go

 :)

i did a breadboard experiment where i measured voltages and calculated voltage drops

also they wanted me to take measurements at certain points rather than across each component

IMG_20230910_135904864.jpg

and im amazed at how close they came out...although i messed up on point D gonna have to redo the experiment

IMG_20230910_135932526.jpg

even though i had the ac? portion of the circuit on the left it was a non factor as I couldnt really get anything out of it.
maybe that was the point

still im missing that 1v pp

gonna have to do some more calculation

What is the symbol in the circle on the far left side?
Can you post the circuit from the textbook?

It looks to me like there is an AC source on the left side (circle with symbol), and a DC source on the right side.  That should not be done.  You can not get a p-p voltage from a DC supplied passive circuit like that.

thank you sir

here is the reference

IMG_20230911_045522631.jpg

IMG_20230911_045608490.jpg

i thought it would be the 1 v riding on the dc like a 25v tall wave

at the end of the day all i did was make a dc circuit

 ::)

ok after further review....looks like i need to work parts 5 and 6

doh

ok i repeated the experiment...and did the measurements for 5 b

still need to do the calculations 5 a

IMG_20230911_150223822_HDR.jpg

also my scope and probe needs to be calibrated...

 :P

also that dc measurement at point d looks better this time

got tons of pics but figured i would chill out and stop posting millions of pics
if you need to look at something let me know

the capacitor i used is electrolytic was in a pickle about the orientation....
 :o but its still alive

What sort of breadboard are you using ?
If you haven't got a solder-less plug in breadboard I would highly recommend you get one.
https://www.taydaelectronics.com/hardware/breadboards/830-point-solder-less-plug-in-breadboard.html

As you get further along you are going to get more and more components and gear, I would recommend you find a good value place to buy your components in bulk.
I use Tayda to get most of my supplies as they are cheap and I only build stuff for home use, if I was going to sell my gear I might buy more expensive components but I find Tayda is more then good enough for me.

I buy resistors in lots of 50, capacitors in lots of 10 or more, diodes usually 50.
I build stomp boxes and amps for family mostly so I find that amount will keep me going for a while, if I bought the components locally I would pay more for a bag of 5 resistors then lots of 50 from Tayda.

There are bound to be more good value shops around but I will stick with Tayda myself as they send the components in nice little zip-lock bags.

I usually buy a fair amount at a go because of shipping costs to make it cost effective.

Cheers
Mick
 

thank you sir i am using a jameco board

IMG_20230911_144535061.jpg

pretty funny last night at work i was calculating voltage drop for the ac circuit and trying to figure out which side was +

so i was like oh yeah look at the terminals of the bnc cord from the SG

then later i was

....oh ok........ ::)  :)

thats cool that you like pedals

maybe somebody would like to see my old pedals

here is one i bought almost 40 yrs ago

IMG_20230912_115336048.jpg

i actually never cared for it much made it sound like a chainsaw

Quote from: saturated on September 12, 2023, 01:02:11 PMmade it sound like a chainsaw

That's funny, there is a PCB for a HM2 clone pedal build and they named it the "Swedish Chainsaw".
https://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=35&products_id=565

  I looked at that tayda website they seem like some good people i will have to try them out next time. 

I unearthed this yesterday wondering if i could use it

IMG_20230912_180130328.jpg

despite being out in the weather they actually still spin

says powerstat 20

IMG_20230912_180157878.jpg

probably too far gone to be useful

I would say they are too far gone, but when I zoomed right into the copper windings it looks like the varnish is still good.
They look like nice rheostats that might be ok after a full restoration, but it depends on the metal having survived in the core.

If they clean up ok they could be re-dipped in varnished then tested too se if they are ok.

Rheostats are very useful for bringing up the mains voltage nice and slow when testing electronic gear.
I have a small one and a large one myself.

What are the ratings on them ?

hello sir here is another pic

IMG_20230912_180137500.jpg

and of the complete device which purpose is unknown

IMG_20230912_180205191.jpg

brief google of "F. F. Hutton" shows they were active 1950s era and known for pneumatic devices.....

probably not much help but here is rear

IMG_20230912_180458320.jpg

It looks ok, they need a big overhaul before you would know if they could be saved.
So it's 120V AC in and you can get 0-140V AC out at 3 amps, say 400 watts.
They would be very nice on a workbench, but they would have to be enclosed with a lead for input and a power outlet for outlet voltage if you are not a qualified technician just for safety.

Me, I would salvage them and use them, but I know whats involved having been a licensed electrician since 1980.

The main worry I can see is rust in any steel parts as that might have caused an internal short in the windings, all the rest can be cleaned and inspected very gently.

It might be cheaper to buy  a new unit with the time and effort (and money) it will take to restore them, but I still would.

Mild soap and a toothbrush would be my starting point, some WD40 to loosen up any seized nuts and bolts and slowly pull them apart.
Some electrical cleaner on the electric parts, rub the windings that have been bared for the carbon brush to run on with something slightly abrasive, you can get stones made for polishing up commutators in motors that are perfect for that.
(I often clean contacts with an eraser made for ink, especially old PCB's before soldering)

Reassemble and bake in an oven to remove moisture and test the insulation with a HV megger, all done.

thank you sir i will ask him if he wants to part with them

I did some more breadboard tonight same experiment but with a 100 uf cap across a resistor

IMG_20230914_220053172.jpg

im confused by that 0.4v but i think my ground adj is off or something having to do with where my scope probes are...idk

its probably supposed to be 0.0v

but the scope def shows what happens

and the multimeter showed the dc circuit voltage readings were unchanged by the capacitor

 :P

btw sir I had no idea what an HV Megger was..so I enjoyed reading about it.

nothing to do with it but reminded me of when i was trying to fix our dishwasher.
I removed the circulation pump and tested resistance..it was some crazy number like in the mega ohm range.
I was like "yep thats no good!" and ordered a replacement.
when the replacement arrived I checked resistance on it...and it was the same.

however the replacement pump fixed the dishwasher.

later i was reading that those pumps(motors) are something called ? continuous phase synchronous ? motors

:P

EDIT  supposed to be SINGLE PHASE

The biggest fault with dishwashers is that something small gets in the drain pump and jams the impeller, just remove the item and it's all good.

The second biggest fault is that someone uses normal dishwashing detergent in them and they over suds and then overflow, this causes a small float switch under the machine to cut the machine out, and usually the drain pump runs all the time.
This happens a lot when people have had a party and some good samaritan decides to load the dishwasher and start it for you.
The best way to kill the bubbles is to add some hair conditioner into the machine, it works really fast and that's what most Hotels do.

I once did a house call and found the drain pump blocked, I stuck my hand into the dirty water and I pulled a used hypodermic needle out of the drain pump. I was not impressed.
Another time I stuck my hand into the dirty water and found they had filled it up with hydrochloric acid to try to unblock the machine, that burnt.

pretty interesting
I think in my case some broken glass put the impeller in a bind and so the pump motor burned up

I tried bringing home washers and dryers for a while and fixing and selling but i guess the mentality is different these days
nobody wants a bulletproof roper or kenmore that will last forever....

oh well rant over

while I got you here I am really struggling with trying to understand how to be safe with oscilloscope grounding.
I was going to put a two prong adapter on the cord to unground it but maybe that is not a good idea.

I dont plan on working on any old tube amps or crazy vintage receivers anytime soon.

I will continue to try and learn how to keep my work safe.

thanks for your help.

I was watching a video on my tv and took a pic of the screen

anybody recognize these guys  :P



IMG_20230922_221558791.jpg

while I got you here I am really struggling with trying to understand how to be safe with oscilloscope grounding.
I was going to put a two prong adapter on the cord to unground it but maybe that is not a good idea.
[/quote]

It has been a long time since I used my scope, and my scope is a real CRO.
I usually use one ground clamp that I attach to the 0v rail, as long as the 0v rail is grounded.

All my probes have a removable ground wire so all I am left with is the probe itself, I leave one probe with the ground wire attached.
My old "cathode ray oscilloscope" is nothing like the modern units most people have today, turn it on, have a cupper, use it.

I tried to post earlier. Do you want a working variac? If so PM for details.
nosaj

Here is the first one.
nosaj

Here is the second one.
nosaj

that looks pretty nice
thanks for the offer let me read up on them and see if I can use it
 :)

btw i brought home a new volt meter

supposed to be real accurate
:)

IMG_20230929_173225020.jpg

yes it needs a nice hot bath

IMG_20230929_173230915.jpg

and a power cord...no need for the dbt

IMG_20230929_173403818.jpg

my limited google indicates possibly it is a kelvin varley divider etc

there is a youtube video of a fluke 881a in action

will be fun to replace the power cord and see if its even close

on my to do list...need to build a curve tracer and connect to my oscilloscope

either that or find a tek 575  ::)

 :)

alright i wanted to test my new voltmeter

so first task was unsoldering the disintegrating power cord

IMG_20231001_184427502.jpg

which wasnt easy

hot from transformer

IMG_20231001_184441952_HDR.jpg

ground from fuse holder

IMG_20231001_184449296.jpg


and green....common?

IMG_20231001_184456377.jpg

and the disconnected carcass

IMG_20231001_184651425_HDR.jpg

this is a lot of work but oh well i guess its good practice

gonna be all for naught if i get a new cord on there and it fails dbt
because at that point im stopping

also i am discouraged to see silver metal transistors...to me that means germanium...but idk i have no idea

 :)

so i wired up the replacement power cord..which wasnt looking so great either  ::)
no matter how far back i peeled back the outside sheathing the insulation on the interior wires was crumbling
but it appeared the white insulation was more robust...so i went with it

also the wierd lookin fuse was blown
i do not have anything that remotely resembles this

IMG_20231001_194950220_BURST000_COVER_TOP.jpg

so based on the markings i scared up a plain ol 1/4 amp fuse and stuck it in

next up connected my UDBT (ugly dbt)

powered up...turned it on and all was eerily quiet

IMG_20231001_194404003.jpg

I thought well something is open somewhere...this is too good to be true...was fixing to disconnect everything and to my astonishment saw a light on

IMG_20231001_194413948.jpg

so i guess my next move is to input a known voltage and then try to rotate the bottom knobs until it matches up....

 :)

i tried it out for a while but didnt get too far

IMG_20231001_203353952.jpg

amazingly all 4 lights at the bottom work

its def responding...if i turn the second digit to zero the meter deflects

IMG_20231001_203751139.jpg



and back to one which i presume is ten....it goes back

IMG_20231001_203804051.jpg


oh well that was fun

time to catch the rest of some football

Quote from: saturated on October 01, 2023, 02:52:19 PMon my to do list...need to build a curve tracer and connect to my oscilloscope

I don't know if you have a transistor tester yet, but a modern one can be a great item to have, for very little money you can pick up something that can do some amazing measurements on components.
I bought one several years ago but I think I need a new better one as they get better so fast.
I bought one without a case but then ended up buying a case many years later so the final cost was the same as one with a case in the first place.
The old one I have now is in this video on you-tube, the one on the right.
It would be worth spending some time and finding a very cheap one that can do everything the more expensive ones can do, just have to keep looking till you find one.

https://www.youtube.com/watch?v=-pEmM0Kt2UY

Cheers
Mick
 PS...If you find a great cheap one ....let us know :)

See this page, particularly 'differential voltmeter' and the explanation of the 5 knobs:
https://control.com/textbook/dc-electricity/null-balance-voltage-measurement/

some more groundbreaking earth shattering cutting edge work today  ::)

wanted to connect signal generator to amp

IMG_20231002_175853982.jpg

IMG_20231002_175908599.jpg

that was fun
but too easy and predictable

better yet would be to have the amp opened up and try to find the signal by probing around on some components

i made a video with outer limits sound effects

 :)

ok i wanted to fix my heathkit oscilloscope but alas i feel its journey has possibly reached its end

I kept probing carefully around the low voltage ps stuff and got decent voltages...kinda started to look at the sweep trigger board and four ICs located there

tried to get some voltages without much luck...

decided to unplug IC303 and as gentle as i could be to my horror when it came out some of the pins broke off or disintegrated...

 :'(
IMG_20231005_141537897.jpg

i guess i could buy new sockets and new ICs....idk

i dont even know what they are....yes looks like some water/humidity damage there

i live in the swamp and this was in a building for years with no a/c and leaky roof

IMG_20231005_141615076.jpg

so TLDR if i could obtain the sockets and chips at a reasonable price that would be a good project for me


edit..apparently said component is motorola 443-4

443-4 looks like a Heathkit part number. Look for an assembly manual on the internet or possibly a Heathkit cross-reference. Be sure to observe the "1" printed on the PCB as the only indicator of which way to insert the IC. The socket doesn't appear to have any marking telling you which way to insert the chip.

Heathkit Cross Reference:
Heathkit_components_cross_reference_2003.pdf

Whats the model of the Scope ?

thanks guys

it is SO-4540

which (I think) means preassembled...

 :)

I found this page with lots of info on other model oscilloscopes, but not your one.
It is possible they might have very similar schematics or even the same.
Have a look :
https://www.vintage-radio.info/heathkit/index.htm

and just as I was going to press "post" I found these photos:

IO4540_01_UpperLeft.jpgIO4540_02_UpperRight.jpgIO4540_03_LowerRight.jpgIO4540_04_LowerLeft.jpg

It's best to open the pictures in a new window, or download the link when on the small pictures.

thanks again!!  i have some pics like that but the ones you posted above have better resolution...mine have a dark haze and are tough to read..
I have pretty much dismissed desktop computers and monitors as obsolete and dont have one anymore in my work space but i was seriously considering getting one out of storage and bringing it back in so i can actually see and read stuff instead of squinting and zooming images on my phone.

anyway i wanted to ask about this diagram...i had looked at it a few days ago because i wanted to take voltage readings on the legs of the chips.. but i couldnt make sense of it and just scratched my head
especially how 4.8v gets divided into 14v....
IMG_20231006_110529511.jpg

but then i saw this one

IMG_20231006_111828533.jpg

and was further lost...i have a lot to learn obviously

then they had separate little boolean bullet symbols for IC 301....so I need to do some homework on this stuff

anyway have a great week end

 :)

I think it would be a very big step to try to understand "Logic IC's" from the start.
There are several websites to learn from, and also many books and information on the NET that can guide you on the subject. Texas Instruments have some good info but it might get complicated very fast.
I would start here : https://learn.sparkfun.com/tutorials/digital-logic/all

The first picture shows you have a +4.8v supply that goes to 4 IC's (IC-301 to IC-304)
Pin 14 on the IC's is the positive voltage supply pin (Marked VCC)
Pin 7 on the IC's is the negative voltage supply pin (Marked GND)

In schematics VCC is often the marking for the positive supply, GND is the ground or 0V supply and finally VDD is often the negative supply.

So basically it just shows you have +4.8 volts to pin 14 on those chips and 0 volts on pin 7.

The second drawing you did is of IC303 (SN7472), it is a block diagram of its function, that IC is a "AND GATED J-K MASTER-SLAVE FLIP-FLOPS WITH CLEAR AND RESET".
What that means is that that is the very deep end of the pool for you where headaches lurk, you can try to understand it by reading up on it, I do and it gives me a headache even thinking about it.

All of those logic IC's have modules in them, and the modules are drawn with different symbols that indicates what they do, if you deal with them often its easy to follow but its been to long ago for me to try.

You might not be able to get the exact replacement part for all those IC's but there are many other chips that can do the same function with slightly different part numbers.

I tried to clean up the pictures, I don't know if it is better or worse.
Also some data sheets.

thanks for helping and taking the time to post and attach that content

you rock  8)


and you are right...the data sheets are very interesting....and extremely intimidating  :)

I am relieved..i think..that they are plug and play

I will try to track them down

a brief search last night showed that two are plentiful and cheap..like 36 cents...another is available for like six dollars but the other one is only available from a place in Canada

I just dug into my box of junk to take a look at what ICs I had to see if I could get lucky

IMG_20231009_125739111.jpg

from left to right...

RS 7400N seven legs

DM7490AN seven legs

S7409 seven legs

a bunch of HCF4040BE eight legs

and a bunch of seven legged sockets....

time to start ordering some stuff

 ;)

You might try to locate some "14 pin DIP component carriers". These can be used to adapt other IC's to the socket on the Heathkit PCB or solder the old 7472 with the mangled legs to one to see if the chip still works. The 7472 is not a popular chip and may be expensive to find.

It looks to me like the chip is just used in the divide by two mode where J and K inputs are both a logic High and the Set and Reset inputs are active. An old practice was to just leave inputs unconnected to anything to act as logic High inputs. (A bad practice). Half of a 7474 chip can be adapted to perform this function.

thanks for you help sir I am enjoying becoming familar with some of these terms like 14 dual inline package

I shopped around a bit and found some of the components as well as encountering some more terminology...like inserting "LS" in the numerical designation.
apart from learning what it stands for "low power schottkey?" no i dont know what it means

IMG_20231010_205606122.jpg

meanwhile I think I need to go back and see if the 1 pins on the chips on that board are getting voltage..

 :)

edit...pin 14

edit 2...just plugged it in and checked those pin 14 voltages
IC 301 looked pretty good but the other ones only showed about 1.5v...
I was surprised to see anything...that board is pretty rough
who knows

If nothing else comes out of it, the experience you are getting out of this is priceless in the long run.
Keep it up.

Edit: And most likely cheaper then spending your time in the local bar as well.

well guys I submit my latest quandary  :'(

I wanted to work on that metronome from a while back...I remember getting frustrated trying to ohm test the switched potentiometer.

I could swear i even wrote it down...the black mains? were soldered to the rear terminals...

when I connect my multimeter I get nothing from the rear terminals except "1" which i presume means "open"
turning on and off, all the way in either direction...no change
now when I test the other three terminals I get min and max (100k ohm) but the switch doesnt do anything

I have googled the heck out of this and retested and rechecked
it is a clarostat...I saw an ebay pic of one that had a wire from one of the three going to one of the rear

anyhow does anybody know what the terminals on the back are for ?

IMG_20231012_234031833.jpg

IMG_20231011_134832511.jpg

im guessing they are supposed to be earth or common idk

also there are no markings on the back except a funny looking dogbone shaped symbol....besides manufacturers info

The 2 lugs on the back of the pot are a switch.  If it is measuring like that it must be bad.
You can see it (switch) was wired in series with the fuse in your other thread here:
https://www.ssguitar.com/index.php?msg=41327

Did you put a knob on the shaft before you tried it ?
Some of the older ones might need a bit more force to turn the last bit so it activates the switch.

thanks guys for the help
yes sir i am stressing my fingers and it is clicking on and off
I am going to put this thing back together bypassing that pot
I just need a new kbpo6 ( edit: 2KBPO6 )which is obsolete..but out there...the one i took out tested good i just dont want to solder it back in. 

so concerning this metronome..nothing makes sense...it had what i presume was a dead short...yet the on off switch is open both ways. idk

im wondering now if one of those terminals was making contact with the metal case...hard to tell now that i have gone in and messed up the original conditions.
a good lesson to watch for that kind of stuff next time.
anyhow I dont want to make a habit of disassembling everything and throwing my hands up so that is my plan: solder in replacement bridge rectifier..bypass on off vol switched pot and see if i can get some life out of it.

not to complicate things but another issue..the big dial potentiometer to adjust speed...has no stops...just turns infinitely in either direction.

ok time to get my meter out and take a look

 :)  ::)

well that was informative
it just starts over and over if you keep spinning

IMG_20231013_211734393.jpg

IMG_20231013_211832262.jpg

amazing

IMG_20231013_211936821.jpg

but...alas the task of reinserting this is not easy...connected to each terminal are very fine jumpers....

from what i remember i didnt sever them they basically disconnected just by breathing on them

IMG_20231013_212504935.jpg

ugghhh

 :(

That potentiometer is meant to rotate fully around, it is made that way.
That one has no inbuilt stops on the shaft.

ok this evening I wanted to check some voltages on my oscilloscope now that thanks to Mr Mick I have a schematic I can actually read.

I also learned that wires have two ends.  meaning all the while I knew to stay away from the wires on the end of the CRT.
I should have known that the ends of those wires are in the top middle of the following photo.

particularly the larger diameter red ones

IMG_20231014_210635155.jpg

I only became aware of this as happily trudging along taking measurements suddenly saw a large negative number.

I was somewhat pleased yet perplexed that the numbers (to me) looked pretty good...? as if they were reasonably close to those on the schematic.
edit: also the anode of d408 measures 21.8v

so moving on to the board with the ICs I quickly noticed a trend...that is there was no voltage to be had..

IMG_20231014_210754446.jpg

I was a bit uneasy because a couple days ago I was able to get low voltage on those IC pin 14s...now nothing. 

now granted IC 303 is vacant but idk...

Im glad i didnt start ripping out capacitors and stuff.

 :P

one thing I need to work on is checking resistors.  I kinda dont want to because I have to desolder one leg and lift it.

 :'(

pretty funny what i just learned

I was making circuits on breadboard and trying to measure voltage drops with my oscilloscope.

I was getting frustrated...crazy whacked numbers...trying to make sense of it..which I could not.

turns out I thought a scope was like a multimeter  :)

just connect it across the component in question..just like a multimeter...right?

NO 

:P

(of course you already know this)

the ground terminal on oscilloscope probe

drumroll......

spoiler....

is actually a ground.

:)

Quote from: saturated on October 14, 2023, 10:25:03 PMI also learned that wires have two ends.  meaning all the while I knew to stay away from the wires on the end of the CRT.
I should have known that the ends of those wires are in the top middle of the following photo.

You will quickly learn to be careful if you touch those "hot" wires, but don't worry, it only hurts till you pass out.
You just need to worry about waking up after you pass out, it's not guaranteed.

If you need a probe to measure the HOT wires i have a 30kv probe you can have for shipping.
nosaj

man this forum is the best and you guys can take all the credit

i did some deep digging at my friends junk store and found some nos ic

IMG_20231020_171654443_HDR.jpg

i havent looked them up yet

IMG_20231020_171725741_HDR.jpg

there is a prescription bottle full of used transistors from 1970

 :)

if anybody is looking for anything let me know it could be in here

and the first item pulled from the grab bag....
I thought these were some kind of lights or something

IMG_20231021_221559602.jpg


turns out they are ultrasonic sensors

I am going to read more about them...like if they detect people or if it has to be metal
 :P

kinda cool

might be fun to play around with

and some more laid out and identified...somewhat

spoiler...all the green boxes are the same thing 2N3391A

IMG_20231021_224906771_HDR.jpg

IMG_20231021_230713978.jpg

probably pretty common stuff

some big diodes  :)

i was curious about a couple items...the ecg3036 has like a lightbulb on top of it... :o

and the rca sk3006 has four legs

i know...google is my friend

 :)

Light bulb on top sounds like a photo transistor of some sort.
The 4 lead SK3006 is a Germanium transistor that has an extra leg for the metal cap on top as far as I know, and the SK3004 is also a Germanium transistor.
Some Germanium transistors are becoming expensive since they are no longer available and are very coveted for Fuzz pedals.

You should test all the Germaniums individually and record the findings.
https://www.radiomuseum.org/tubes/tube_sk3006.html

Datasheet is too big to upload here so here is the link:
http://bitsavers.trailing-edge.com/components/rca/SPG-202Z_RCA_SK_Series_Replacement_Guide_1981.pdf

Look at page 26 for the SK3004 and SK3006

Quote from: nosaj on October 20, 2023, 03:21:56 PMIf you need a probe to measure the HOT wires i have a 30kv probe you can have for shipping.
nosaj

that is very kind of you i appreciate the offer if i get it i def want to pay for it

a question i had...do HV probes eliminate all the fireworks (arcing, sparks flying..) that i got with my normal multimeter probe ?

 :'(

edit...nm i watched some videos where really high voltage was being probed and there were no fireworks...maybe the density/girth/resistance of the hv probe helps

well guys i wanted to get this over with the suspense was killing me so i looked at all the markings on my newly acquired stash of ICs
I was dreaming that I was the proud owner of mass quantities of rare impossible to find NLA components.... :'(
I was at the least hoping for something I could use in my Heathkit scope...the closest thing was the last one listed..but i need a plain ol 74132
when the one on the sheet is googled...lots of aviation stuff pops up.... ::)

anyway here we go.....


IMG_20231026_230704514.jpg

so now that is over with i dug in there and found this and really like it
but have no idea what it is
ok nm its a baby transformer
 ;)

IMG_20231026_231721704_HDR.jpg

IMG_20231026_231743984_BURST000_COVER_TOP.jpg


anyhow have a great weekend

That looks like a standard audio transformer to me, i don't know what from as my background was industrial electronics.
It would be used to isolate the audio signal between 2 different circuits.

Why do you think the DV74HC132AN will not be the same as the 74132 you need ?
It can handle up to 7v supply and you have 4.8v supply in the scope.
If the chip can handle the voltage and signal then it should be ok.
Hopefully someone who knows for sure can jump in with an answer for you.

The LM358 dual opamps will come in useful in many projects, you could use one to buffer the sinewave output of the ICL8038 signal generator IC that you got there.
The ICL8038 has square, triangle and sinewave outputs and will make some great signal generators for you to build.

Yes, the 74HC132 is backward compatible for 74132 usage.  The DV is just a brand prefix I believe.
The audio transformer might have been used for mic inputs, as 500 Z impedance is probably close enough to the standard 600 ohm.
Here's one in use for matching PC sound card out to PA mixer mic input:
https://sound-au.com/project133.htm

hey guys I had a question about circuit board layout specifically why are components clearly labeled but not resistors

as an example I am (randomly..) finding voltages on the schematic and then testing

for instance I want to see if there is 9v on one end of R109

IO4540_01_UpperLeft (2).jpg

now...D103 is easy to find..anode and cathode clearly marked

that is easy enough..

IMG_20231030_130045042.jpg

but now when I want to measure R109 its not marked and I am guessing...aside from the color code can help

IMG_20231030_130010923.jpg

idk if that was the right one..

so that is my question why not label the board R109 etc

 :'(


btw i am putting this scope away and coming back to it when I learn a bit more

ok nm i guess you need to see the bottom of the board where the traces go

:'(

:)

A zero ohm reading between components would confirm a connection without flipping the board.

I think it should have been marked, but then in the stomp-boxes I make up there is no room so my markings are under the components.
Once you mount a resistor you can no longer see what the part number is in most of my PCB's I make up.
But then my PCB's are for myself, and anyone I share them with on a forum.

hey guys i just wanna say thanks again for all your help i figured it might help to post a pic of myself so you can put an ugly mug to my inquires

anyhow this was just now..cleaning out my garage sweeping out racoon scat on a beautiful (finally) sunny fall day

 moving a gun safe probably gonna sell it

gettin rid of a few things

 etc

IMG_20231101_125303574.jpg


yep im old just turned 60

im grateful i found this hobby I have a lot of personal achievements, accomplishments and failures but i was always intimidated and bewildered by anything electrical

you guys rock

\m/

I decided to quit trying to fix my heathkit scope until I have a bit more skills.  I dont want to butcher it to the point where it becomes a basket case.  Im encouraged that some of the measurements I have taken are in agreement with the schematic. Also that one board that has some rusty (trimmer pots?) I was expecting the bottom to be beyond recognition but instead when i flipped it over it was nice and shiny...really looked awesome. I also got ahold of a hv probe i wanted to measure that 1640 or whatever it was and i still got a ton of fireworks..sparks and arcing.
so yeah im putting it away for a while before i kill myself or it and getting back to doing my little experiments in my book.
which i just finished chap 2 (diodes) and it got pretty heavy with dynamic and bulk resistance, junction voltage, operating points or load lines...cant remember.  you draw lines when If equal zero and Vf equal zero with different resistors etc which i wasnt crazy about but figured its necessary just suck it up and get through it so I can get to the good stuff.
which kinda happened so here i am

IMG_20231102_113835742.jpg

this should be exciting

im looking forward to doing the experiments

all i know or think is zener diodes are kind of like backwards diodes...idk 

 ::)

Quote from: saturated on November 02, 2023, 07:29:17 PMall i know or think is zener diodes are kind of like backwards diodes...idk 

 ::)

Almost.  Standard diodes only allow current in one direction, zeners can flow in both directions.  Zeners will operate similar to a standard diode in forward mode, but in reverse at breakdown voltage they allow current without letting out the magic smoke.

hey guys
hope you are having a good holiday(s)

I have decided in the interest of thoroughness to go back and start an earlier book to the one that i was doing

IMG_20231225_110346339.jpg

IMG_20231225_110405724.jpg

so yes its a step back but i dont want to miss anything and the best thing about this series of books is each chapter has lab exercises

anyhow wanna give everybody a big shout out
stay safe


and keep on rockin \M/

 :)

I have been having this old decade box for a while and kinda didnt have a use for it.
but then in my book breadboard experiments i needed a few resistors that I didnt have
then was groaning about ordering more  :'(

took me a while to figure it out  :P

but maybe i can use this

IMG_20231225_113234208_HDR.jpg

 :)

some of the resistances arent too close but check this out

IMG_20231225_114250403.jpg

 :)

I was getting mad at my cheep aukenien resistors but I was incorrectly not using the fourth band as the multiplier

IMG_20231226_123323864.jpg

IMG_20231226_123335217.jpg

I also tested some old stuff and learned that 3 bands means 20% tolerance

I still like the old resistors better the colors are awesome


IMG_20231226_123923877_HDR.jpg

 :)

welcome back to the advanced epicenter of high tech experimentation
:P

trying to hustle through the easy part of this book so I can get to some good stuff

so today they have me setting up series parallel circuits...calculating resistance..then measuring

IMG_20240110_131921860.jpg

its pretty boring...I must have plugged and chugged a thousand of problems like this in other old textbooks
but the difference now is now I have "lab exercises"
 :P
also next I get to bust out some variable resistors

oh yeah...
 :P

Once you learn all those equations backwards and forward, you will have a much easier time with practical applications like multiple speaker cabs with speakers of various impedances.  Then you can throw power handling into the mix and find the weakest link.   :)

the weather here has been crappy so I set out to make a little component tester
here is a schematic from a video by w2aew

IMG_20240122_134857395.jpg

an old transformer I had was at one time showing 16.3v

so I did some math and figured i needed about 1.2M ohm

IMG_20240122_143835856.jpg

then i went about setting everything up using the transformer, decade box, breadboard, oscilloscope

I was extremely pleased to obtain a typical y=mx+b type resistive sloped rise

IMG_20240122_153755772.jpg

but after that nothing worked out too well.  in fact i was able to obtain a lissijou? shape and I had no capacitor connected.  yet when I tried a capacitor i just got a line.

what I really wanted was a nice L shape from a diode so I eagerly connected one but no L were to be had.

I tried different directions and ground  clips and trigger modes etc but eventually gave up.

 :'( 

oh yeah forgot to put this in

IMG_20240122_155555802.jpg

 :P

Your math is off by some factor of 10 I would think.
He has 6.3V and a 47K resistor, you have roughly 3 times the voltage, maybe should have 120K instead of 1.2M ?
Re-check your calculations.

thank you sir

ha ha too funny when i went back to look at my pad I turned on my calculator and it displayed the last calculation


IMG_20240122_201722220.jpg

IMG_20240122_201730146.jpg

 :P

I went back to try this with 120k ohm
albeit conceding there is probably a myriad of other mitigating factors messing this up that are beyond my comprehension.
but alas it was worth a shot and thanks to G1 for pointing that out... :)

so off we go..dialing in 120k ohm

IMG_20240124_130503018.jpg

and I was able to obtain some much coveted (ugly) L shaped wave form from a diode...just not in the preferred orientation

IMG_20240124_134013424_HDR.jpg

IMG_20240124_134045497_HDR.jpg

I spent a few mins switching ends on the diode and attaching and disconnecting scope lead ground clips and couldnt really make any progress.

I imagine there are some strict parameters that need to be observed for this to work...idk

but it was a cool experiment

 :P
 

I was gonna break this down and put everything away then I remembered I had some zener diodes

so i grabbed one and tried it

IMG_20240124_140326016.jpg

then swapping ends

IMG_20240124_140414060.jpg

so that is cool i just dont know why everything is bassackwards

 :(  :P

also i used to think these were cool heck i cant get away from them

this is what i see with the circuit open

IMG_20240124_140451639.jpg

 :P


EDIT wondering now if i should have switched the scope probes
I did swap the transformer leads but should it really matter since its alternating current

I needed to color code my scope probes...

y was easy...put yellow there

for x I had a choice of blue green and pink

so as a tribute to Paul Gilbert I picked pink for X
:P

IMG_20240124_141310191.jpg

I need some ammeters for my little textbook exercises.

I have been trying to figure out the difference in ac and dc meters.

Im def old skool and have been browsing various junky analogue meters on the auction site. I like the ones that have different terminals so I can start out high and not accidentally blow it up.  :-X
I know i can use my dmm to measure current but i really would rather use something expendable  :P

another problem i have with analogue is im no expert at knowing polarity so maybe if i connect it backwards it wont be good for the meter...whereas a digital would just tell me minus microamps ?

I have some old ammeters that are way to big to measure stuff like micro and milliamps.  I know I can do some calculations and add resistor shunt to make a little meter measure larger but I dont think I can go the other way...ie make for example a 15 amp simpson meter measure micro or milliamps.

peace out

 :)

last night i ordered some old millammeters 0-500 and some centered plus and minus

probably too big for what I need but i figured i would start somewhere and try not to blow em up

I really want to get a blue anatek esr meter but i am gonna make myself build one (diy esr meter) on my own first

I have looked at a few put together on videos and various schematics

I guess i need to breadboard it first then try to assemble a diy version

everything i see says i need a microammeter so i may have to scare one up

 :P

Today was somewhat exciting as it marks the first experiment to measure current

My assignment in my book was to lay out a circuit with a 1.5k resistor and measure current at 6, 12, and 18v then compare with calculated

For some reason I was really nervous shaking like a leaf idk yeah I was kinda freaked out thinking I was gonna blow something up

Especially when I had to take it up to 18v

But it went off without a hitch. All good

IMG_20240211_134713346_HDR.jpg

 :-[  :P

Most meters have a separate input to connect one of the probes to when you measure current. There is almost always an internal fuse that will blow if you forget to move the probe back to the Voltage jack when measuring Voltage.

Yes sir thank you

:)

They also had me put a 10 ohm resistor in series and measure the voltage drop across it then calculate current V/R and it was spot on to the ammeter current reading

I was impressed kinda makes you wonder why even bother with putting an ammeter in series

:(  :P

I like to use my meter's current mode to measure how much an effects pedal consumes. Simply use a 9V battery, unsnap one side of the battery connector and touch the probes between the battery terminal and the side of the connector you just unplugged.

I love your dedication to learn electronics, not many people would take it upon themself to do it so thoroughly with textbooks and lessons.
By the end of this year I think you will be good enough to really get into pedal designs and even amplifiers.
It won't be long before you can start designing your own PCB's and have them fabricated so you can build your own projects.
It is great fun when you want a pedal that is no longer made and the old ones are costing a fortune, make them yourself really cheap.
Keep up the great work.
Cheers
Mick

I thought I would I submit a graphical image of how I feel when you and the others are discussing tech in other threads





220px-Uncertain_Future_(Forced_Entry_album).jpg


 :P


But thanks you guys rock  8)  :)

Last night I learned that he/she who uses multimeter to measure current but forgets to switch positive lead back before measuring voltage finds themselves looking online for a $30 fuse

 :P  :'(  :)

That is too much for a normal fuse, what type is it ?
Photo ?
It is usually a M205 fuse that costs cents, sometimes a ceramic type but still cheap.

Quote from: Tassieviking on February 22, 2024, 12:01:47 PMIt is usually a M205 fuse that costs cents, sometimes a ceramic type but still cheap.

My meter uses a regular fuse for the 2A range but has a special fuse for the 10A range (that has it's own probe port).
The special fuse is very expensive due to safety ratings and odd size.
You can find cheap ones from China but I think they are fake as far as the safety ratings go.
Mine is not a Fluke, but this will give you an idea:
https://www.fluke-direct.ca/online/fluke-instruments-replacement-fuses

Thanks guys
Trying to remember from last night but I think it is called amprobe fp700

2A 1500V fast blow

8x65 mm

$30 is for a 2-pack, looks like you can't buy them separately.

Crap !!!!
I just went and pulled apart 2 of my Flukes and I have weird fuses as well, I think I have replaced some a long time ago as well but the company I worked for had a draw full of them.
I wish I had kept some spares with the meters now.

No wonder I have some cheap Uni-T meters on the workshop bench, I think they cost around $30 when I bought them. (Many years ago). I know they use cheap fuses as I blew one working on my car.

You can get some fairly decent meters on Ebay for under $20 ($10 up) that are ok if you are only working on low voltage stuff at home for yourself. I would only get Cat3 rated stuff at least.

I will leave my Flukes to have a rest unless I decide to start working for a living again.
I do not need a good meter anymore as the highest voltage I work with now will be  240v mains in my own gear.
EDIT: maybe a bit more in valve amps (a lot more).
Any Cat3 meters should be enough for any private use I think.

Roger that

These days can buy entire meters for that. 

Anyhow I ordered a pair

Lesson learned $$$

I will def have a dedicated current lead/probe with an unpleasant note and warning on the minigrabber portion.

 >:(

 :P

I have seen multimeters that physically block the holes when you turn the knob so it is only possible to use the volt probe when volt is selected and only amp plug when amps is selected, but it was many years ago.
I wonder if you can still get some like that anymore, maybe it was just a temporary fad that went for a while.

Quote from: Tassieviking on February 26, 2024, 10:31:55 AMI have seen multimeters that physically block the holes when you turn the knob so it is only possible to use the volt probe when volt is selected

I think if you forget you were in current mode, you will likely to forget to turn the knob as well.  So then you would still do damage with the probes, which are acting as a straight piece of wire in current ranges.
My current range require switching ports, and there is a beeper that goes off if I choose any other range while plugged into the 10A port.
Still doesn't help me if I forget to switch range.   :-[

Ok guys back in business

Got my fuses in this evening

IMG_20240229_185114550.jpg

Despite shaking in my boots I proceeded

Read the manual and they said remove front six 2mm hex head. So I did that then spent like 30 mins trying to separate the case halves had to use an ice scraper and I didn't think it would ever happen.  But finally slowly but surely they opened up to a great sigh of relief. 

IMG_20240229_191934658.jpg

Removed the old fuse and tested with another meter...open.

Put everything back together and now reading current once again

IMG_20240229_195749401.jpg

Some good news I was wondering if I had to do this all over again to change the battery but it has a separate door.

IMG_20240229_192818914.jpg

 :P

A startling fact when I went to test I found my power supply had been on since the mishap
I went to plug it in and it was already plugged in. Then I went to turn it on and....it was already on.   :'(  :P
 :(
Gonna have to put up a sign.

But at least the voltage control was turned all the way down. 

IMG_20240229_200950328.jpg

So hey all good I suppose that was fun but had to spend some money

 :)

Wow that power supply was on for eight days
 :(

Oh well one time I was reading about tv station or recording studio or some type of place like that and they never ever turned anything off and that was when they had tube equipment.  And some noob trying to do a good job would get chewed out for turning something off.

 :)

Lots of modern electronic equipment has standby circuitry that is always running unless you unplug it from the wall.

So I got to thinking why don't I just put a fuse in my test lead that is less than 2 amps.

It should be plenty for my little Micky 🐭 Mouse 🐁 experiments.  It's not like I'm in a plant or industrial commercial setting poking around.

So I looked around my collection of glass and blade fuses to see what I could come up with.  I was sure that I could scare up a few fuse holders that never got used and accumulated but couldn't find any.

So now that is the plan.  I would have liked to find a 1.5 A fuse but I only found stuff like 0.5 A and much larger.
And all in glass none of the blade automotive fuses were less than 5A maybe 10.

So I had always wondered about voltage ratings on capacitors and fuses and I'm guessing that a component with a lower voltage ratings will be shorted like arcing by a higher voltage.

For example if I have a 250v fuse and I apply 1500v it will short/arc/jump across it?  Rather than open as intended.....idk just thinking out loud maybe I'm wrong.

I know when I had a HV probe and tried to check some HV on an oscilloscope it didn't help it arcd and sparks flew like crazy.

 :'(

When the fuse voltage rating is less than the circuit requires, the possible arcing is more likely after the fuse has blown.
Your probes have a voltage safety rating as well, and that would be lost with any modification of the probes, no matter how high the fuse rating.

You can buy leads that have fuses in them, but they are not really cheap if it is for home use.
If you get the Fluke ones you still have to buy expensive fuses.
My set has a ceramic 3AG fuse in them and they are ok to use, they are a bit bulky though.
https://au.rs-online.com/web/p/multimeter-leads/0204583

Seems like my Topward 6303 has a problem. I had noticed the left side having trouble getting above 15v now it won't at all.  The right hand seems to be ok.


Must need a capacitor or something.  I'm not worried about it now besides if I need more voltage I think I can hook up both sides in series.

IMG_20240308_185841120_HDR.jpg

Ok I hooked them up in series and they are doing good in harmony but that left side can't get past 15v and in fact starts sinking

IMG_20240308_191209961_HDR.jpg

I'm not touching this thing anytime soon apparently the components are packed like sardines on the inside and I have plenty of voltage.

 :-[

Yesterday a coworker brought a line6 pod 500 to work he said take it home and try it out.
I get it home and can't even figure out how to connect it to an amp.  Watched one video about it and still got confused.  I will Google it some more today.

Guitar in is easy enough.  But then there were two outlets "unbalanced mono" each left and right.

Uughhh  >:(

IMG_20240315_090344065.jpg

IMG_20240315_090455284.jpg

IMG_20240315_090503990.jpg

I get it that there's all kind of crazy stuff people can do that's why all the extra jacks etc

But I'm not looking to be the next Tom Scholz
I just want to hook it up like a pedal and get some overdrive and delay flange etc

 :-[

Ok I think it's guitar in

And out is fx send

 :P

Ok I finally got a sound out of it
It actually sounds AWESOME 👍😎

one thing to note before you toss this through a window....the waah pedal is volume  :-X
If the pedal is all the way down it's not gonna work
:-X  :'(
Also I had to use 1/4 L Mono out to amp.

As far as all the other stuff my head is spinning it's gonna take some time

IMG_20240315_095644068_HDR.jpg

https://line6.com/support/manuals/podhd500x

Thank you sir !!

I'm still struggling mightily with it.

Anyhow here is my new milliamp reading super duper current probe.

This time if I make a boo boo it has a 500 mA fuse.

IMG_20240316_161925858.jpg

Speaking of struggling I did a crappy job on this banana 🍌 plug.
Maybe it wasn't supposed to be soldered idk

 :-X

IMG_20240316_161946410.jpg

 :P

I finally figured out that rms and peak and peak to peak might actually be useful  :P

I was looking ahead in my work book and I have to have a voltage ⚡ generator and connect a 6v p-p.

So I was like huh? I don't have a voltage generator  :'( maybe they mean a Variac?

Meanwhile I was looking at my trusty Hickok function generator wondering if I could use that but didn't know if it could supply six volts ac peak to peak. 

I didn't want to fool with my scope so I attached my multimeter changed it to AC and increased the output (on sine wave) but then knew I had to do some math.

I divided 6 by 1.404? But that wasn't quite right so I did 2.808 and that was it.

But something that still 🤔 perplexes me is this:

Is a sine wave from a function generator alternating current?

 ::)

Yes, sine wave is AC.
Normally we call it a 'signal generator' but it is also an AC voltage generator.  Amplitude and frequency are adjustable.
Function generators may also have other kinds of waveforms like triangle or square, which are alternating but not 'pure' AC.  Pure AC is sine.

Thank you sir.

Btw had to put up a sign

Sign sign... everywhere a sign

IMG_20240326_140830931_HDR.jpg

 :P

Not sure what happens if I try to measure resistance on a live circuit  ::)

Meanwhile....onward through the fog.  I am still holding out hope that I can get a trace on this Heathkit oscilloscope.  I ordered the four ICs for it and now I thought I would investigate this power supply by removing caps and reinstalling if testing good.

IMG_20240409_180021057.jpg

Unfortunately (or fortunately) I have removed two and both tested (presumably) good

IMG_20240409_181612651_HDR.jpg


So back in they go

Except...hmmm no way here to test leakage so I checked DC ohms with my meter and I have one that charged up pretty quick to about 70 kohm but then really slowed down

So idk maybe it's leaky

IMG_20240409_182200296.jpg

But as I type it's still creeping up in fact it's at 130 kohm now so maybe it's ok.

 :(

Looks odd but oh well replaced three axial caps with radial (have you seen the price difference between axial and radial)  :-X  :-X

IMG_20240409_194130227.jpg

Still I had not an extra angstrom of length to spare on two of them.  On the third I clipped the lead and used the j-hook method.

Still no green phosphor.... :P  :P

These two ceramics are still hot enough to cook steaks on....

IMG_20240409_194656297_HDR.jpg

At least small steaks...well done... :P

Today I learned:

Just because a resistor has no voltage drop across it and measures the same voltage at each end with respect to ground

Doesn't mean the resistor is shorted

IMG_20240411_181032038.jpg

 ::)

What it does mean is:

The circuit is open.

 :P

And I'm ready to put forth another conclusion:

If I measure xxx volts on one end of a resistor.....and ZERO volts on the other end

Guess what


 :P

It's time to go ISO

 8)

Quote from: saturated on April 09, 2024, 08:49:16 PMThese two ceramics are still hot enough to cook steaks on....

IMG_20240409_194656297_HDR.jpg

At least small steaks...well done... :P

So I'm going out on a limb here and proposing that the 8k ohm 10w resistor is shorted to ground.  It measures 170v on one end and zero on the other.
A quick look at the schematic (a forensically enhanced version kindly provided by the Mighty Mick) to me places cross hairs directly on the zener diode.

IMG_20240412_183931323.jpg

So I'm guessing that the zener diode is shorted...idk.

Or perhaps I'm unfairly blaming it. 

 :P


To be continued...the story of the zener diode that was (possibly) framed

Quote from: saturated on April 11, 2024, 10:29:56 PMWhat it does mean is:

The circuit is open.

 :P

I decided to have a look at this scenario...of course I had seen it and read it in books and kind of unwillingly accepted it.

My point being...take an open circuit...add some resistors in series to the positive side...and your gonna measure the same voltage anywhere along that open series...doesn't matter....one resistor...two resistors...three resistors....there is no voltage drop.  :P

I had to try it.  I made up a three resistor open series circuit connected to 5v.

Well you guys know what happens and already know this.  But seeing it in practice really firmly eliminated any skepticism. 

IMG_20240412_221857456_HDR.jpg

 :P

Obviously this is way over simplified but it still is a powerful tool when probing.

 8)

Quote from: saturated on April 12, 2024, 07:53:18 PMSo I'm going out on a limb here and proposing that the 8k ohm 10w resistor is shorted to ground.  It measures 170v on one end and zero on the other.
A quick look at the schematic (a forensically enhanced version kindly provided by the Mighty Mick) to me places cross hairs directly on the zener diode.

IMG_20240412_183931323.jpg

So I'm guessing that the zener diode is shorted...idk.

That's not going out on a limb, that is good solid logic. (assuming you verified the resistor is ok)  :)

Thanks G1 it's a gorgeous day today with plenty of sunshine so I'm actually fixing to take some good pics of this scope so I can put it on the auction site.  Hope is waning that the ever so coveted green trace will ever appear.
I'm happy that it's been a great learning tool but at this point I don't even know if the CRT is any good. When I first got it there was a slight glow at the small end and it gets dimmer and dimmer.
Also there are a bunch of rusty trim pots then another board has an open somewhere (at the minimum).
A 68v zener is cheap though I might need to see that localized issue settled.
Also I really like that arrow pointing at that node and a diagram of a square wave.
Would be cool to see if that is there with my other scope.
 :P

Meanwhile... experienced my first Chernobyl.

So this metronome I had removed the bridge rectifier a while back and it tested good...oh well

Put a new one in today.... thought it would be fun to hook my meter to the leads before I clipped em and read ac and DC on the different leads.

So I solder it in...crudely soldered the transformer wires back making sure I put the right ones in order.  Plug it in...I'm gathering up my meter and test leads and I hear woosh and see lots of smoke

IMG_20240413_172200060.jpg

And liquid  :-X

Later I was outside and thinking did I put it in backwards or something...or leave a solder bridge?  But looks like the orientation is correct and the solder reasonable (these pics are post meltdown)

IMG_20240413_181201286_HDR.jpg

IMG_20240413_181215344.jpg

Im beyond hoping this thing will be fixed but I did want to replace that part.

Meanwhile I put it on my ugly dbt after the fact yes it was glowing.

 ::)

Follow the trace from the bridge + lead to filter cap.  Is it going to + or - end of cap?

Yes sir appears to go to

-negative terminal of capacitor

IMG_20240413_195736354.jpg

-and the emitter of the tip31a on the right

IMG_20240413_195747043.jpg

and a resistor

The rectifier is installed backwards.

Yes sir thanks I was able to find some old pics of the original part

IMG_20230902_213125123.jpg

IMG_20230902_143844681.jpg

 :P

Ok guys sorry for the bo bo  :'(

Anyhow removed the old one (no easy task) and got a new one in

IMG_20240414_000034517_HDR.jpg

Seems all is good when measuring the (+) pin and two middle pins (~)

(+) pin reads about 40v DC (have no idea what it is supposed to be


IMG_20240413_235645753.jpg

But when I read the middle pins I get like 16v ac but what the heck I get 20v DC

IMG_20240413_235749190.jpg

I think I'll call it a night

 :P

I think your meter is trying to average the AC voltage on the two inner pins.
Try with the meter set to to Volts AC.

Thank you sir I wanted to try and replicate this scenario so I did

I had a device with taps on the back for 12v ac so I rigged it up

IMG_20240416_185533701.jpg


:P

IMG_20240416_184825377.jpg

Results

IMG_20240416_184833702_HDR.jpg

So...idk

I guess it's time to play some Bruce Hornsby

 :P

I decided to put a load on it...12k ohm resistor

Similar results

IMG_20240416_190535472_HDR.jpg

More Bruce

 :P

I have a feeling Bruce says we need some capaci-taters

I think you have your AC source there hooked up to the output pins.
The error when installed backwards would have reversed the + and - output pins.  The AC would have still been correct as it is non-polar.

Yes sir thank you  :P

I decided to take a look at this on my scope

Btw here is the source of 12v ac

IMG_20240416_194208443.jpg

So connecting scope probes directly to cables coming from ac source

IMG_20240417_195114602.jpg

My phone was struggling to get a full trace left to right despite trying to adjust trigger etc the trace was jittery and flickering real bad

So now connect scope probes to (+) and scope ground to (-)

IMG_20240417_195601674.jpg

Which I like that but when I had the scope switched to ac I had just a flat line

Then connecting scope probe to (~)

IMG_20240417_195725684_PORTRAIT.jpg

So I guess everything is cool. 

I'm off to connect some other stuff to the scope and try to get a better full steady trace.

 :P

I'm relieved that my signal generator provided some nice traces

IMG_20240417_201529517_HDR.jpg

IMG_20240417_201543105_HDR.jpg

Idk why the trace from that transformer was so sketchy.

Good afternoon solid state afficianados.

Hope your weekend is going well at least what's left of it.

:P

I had a question about preparing some banana jack patch cable connectors whether or not these needed to be soldered.

The wires shown are not gonna be used they are only to illustrate the routing of the holes in the metal part.


IMG_20240421_135207252.jpg

Maybe I just strip the wire insert it and screw the cap down...idk

Thanks

Quote from: saturated on April 21, 2024, 03:07:37 PMGood afternoon solid state afficianados.

Hope your weekend is going well at least what's left of it.

:P

I had a question about preparing some banana jack patch cable connectors whether or not these needed to be soldered.

The wires shown are not gonna be used they are only to illustrate the routing of the holes in the metal part.


IMG_20240421_135207252.jpg

Maybe I just strip the wire insert it and screw the cap down...idk

Thanks

Use the compression screw on system for now and decide later on after pondering it a bit if you think soldering will be the best final path. As an electrical/electronics engineer, the "right" way of doing things is not always the best or most rational, and primarily taught for what you should expect if you go to work in whatever cornered field of science your education leads you to where far more educated and experienced engineers told me over a decade ago, you'll ultimately end up only using 10-15% of your education wherever it is you settle in lol.

I'm sitting on a huge regret ATM from trying to repair my Zoom G5 some lunatic woman smashed and doing it the "right" way was a disaster! I suspect my repairs won't be successful but fortunately, the unit overall should still work and I will either have to scroll effects to a different bay of the controls since it has 4 and 2 were broken, or stick to programming it by USB and PC.
The only upside to the destruction of that unit is I bought a 2nd one. I got the damn thing 12 years ago brand new when they were about $450, but for $180 on zZounds which a week later, went right back to the normal price. I have some current generation digital floor units that are absolutely amazing, but this 12 year old dinosaur still outperforms them tonally. Parameter wise, the modulation and effect parameter adjustable functions are quite mediocre.