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

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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 

 

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

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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/

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

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

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

that is easy enough..

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

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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

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.....


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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
 

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anyhow have a great weekend

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

and some more laid out and identified...somewhat

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

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probably pretty common stuff

some big diodes 

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

and the rca sk3006 has four legs

i know...google is my friend

 

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

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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
 

kinda cool

might be fun to play around with

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

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

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i havent looked them up yet

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there is a prescription bottle full of used transistors from 1970

 

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 



(of course you already know this)

the ground terminal on oscilloscope probe

drumroll......

spoiler....

is actually a ground.

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.

 

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

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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..

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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.

 

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

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amazing

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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

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ugghhh

 

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