saturated's all encompassing inclusive and exclusive bin thread

[saturated]

some more groundbreaking earth shattering cutting edge work today 

wanted to connect signal generator to amp

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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

 

[saturated]

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...

 
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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

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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

[Loudthud]

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.

[Tassieviking]

Heathkit Cross Reference:
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Whats the model of the Scope ?

[saturated]

thanks guys

it is SO-4540

which (I think) means preassembled...

 

[Tassieviking]

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:

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

[saturated]

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....
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but then i saw this one

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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

 

[Tassieviking]

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.

[Tassieviking]

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

[saturated]

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

you rock 


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

[saturated]

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

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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

 

[Loudthud]

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.

[saturated]

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

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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

[Tassieviking]

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.

[saturated]

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 ?

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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