Replace a balance pot with resistor?

Brawndo

Member
2012-12-06 4:14 am
Hi,

I took apart a Technics SA80 receiver to strip for parts. But I decided it still works and it shouldn't have to die so I can play around.

Anyway, I'm in the process of putting it back together. Everything is fine except that I broke the balance pot while dismantling. It's hard to describe the break, but there's no saving it.

I was hoping to somehow put in a resistor or two to basically set it at zero and just have a non-working balance knob. I'm not that worried about changing the balance.

The problem is, I tried a couple different things and don't know how to do this. I tried jumping it a couple of different ways, but nothing is working. The receiver produces sound but is very quiet.

The pot is a 200k G (couldn't find what the G means).

Is this possible?

Thanks.
 
I don't know what the G means either, but two 100k resistors should work. A mental picture of the potentiometer connections compared to individual resistors will reveal the proper hookup. And don't connect the broken pot at all; you could probably turn it 180° and it will still align with the front panel for aesthetic reasons. Or just leave it out and glue the knob to the front panel.
 

Brawndo

Member
2012-12-06 4:14 am
Thanks for all the responses!

I've been using the service manual but can't for the life of me find the balance pot on the schematic.

And yes, 200k. I tried attaching the manual, but the file is too large.

Also, I tried resistors in the manner gmphadte described. One channel was very quiet, the other got nothing.
 
Location in schemaric
 

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Just a couple other things I can add.
The balance circuit is as I described in post #5. Have you connected the resistors in the same configuration? Are you sure it's the balance pot that's broken? Methinks there's more going on here than what has been disclosed thus far.

In the general info category: If you're using Adobe Reader, you can select Take Snapshot from the Edit pulldown and then select the desired image by dragging your borders with the mouse. Reader will automatically store the image on the clipboard. Then just use a program like Irfanview to paste as a new image, do final editing, etc.
 

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Brawndo

Member
2012-12-06 4:14 am
The balance pot is definitely broken. Physically broken. The body pretty much broke off from the leads.

when I was trying some things earlier, I did it before I desoldered the leads from the board. So maybe I forgot to check after I removed the rest of the pot.

I'll check and report back. I don't believe anything else is wrong with the receiver. Aside from some crackle and the FM radio not working (it was my dad's and I remember being 5 years old and he told me there was no FM) everything was fine the last time I used it.

But we shall see...
 

Brawndo

Member
2012-12-06 4:14 am
Boy is my face red....

While the pot was definitely causing a problem at the beginning, only allowing one channel through, it appears the culprit on the volume issue was something else...

With the thing naked as I tested it, I only gave thought to the main speakers button, being sure that was pressed in. With the volume all the way up and testing with nothing where the balance pot once was, I pressed a button and got a sudden blast of sound before quickly turning the thing off. This was the "Tape Monitor" button....

So I did have a problem before, but volume wasn't the real issue. You guys have helped me out here, I have full volume out of both channels, and I thank you all for your responses. Much appreciated!