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Beginner learning the restoration ropes, are caps my culprit?

V

V1xIII

New Member
Hey everyone, just getting my feet wet in the world of vintage hi-fi. I've always had a passive interest, but the Techmoan channel on YouTube pushed me over the edge and now I've started collecting things from local auctions, etc.

I grabbed a Pioneer Centrex TH-3131 (receiver/turntable/8-track) the other day for $3 and figured it would be a good one to use for a learning experience since it doesn't seem to be anything too special. The 8-track is working, and I got the turntable functioning properly, but there seems to be something wrong with the amp.

It was briefly outputting intelligible sound at lower volumes (though mostly through one channel), but now it can only produce sound above 50% volume and it is a garbled static mess that you can only just barely identify voices/rhythms. I have cleaned the pots and confirmed that the issue affects all inputs. What am I looking at here, bad caps? Transistors?
 
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V1xIII said:
Hey everyone, just getting my feet wet in the world of vintage hi-fi. I've always had a passive interest, but the Techmoan channel on YouTube pushed me over the edge and now I've started collecting things from local auctions, etc.

I grabbed a Pioneer Centrex TH-3131 (receiver/turntable/8-track) the other day for $3 and figured it would be a good one to use for a learning experience since it doesn't seem to be anything too special. The 8-track is working, and I got the turntable functioning properly, but there seems to be something wrong with the amp.

It was briefly outputting intelligible sound at lower volumes (though mostly through one channel), but now it can only produce sound above 50% volume and it is a garbled static mess that you can only just barely identify voices/rhythms. I have cleaned the pots and confirmed that the issue affects all inputs. What am I looking at here, bad caps? Transistors?
Click to expand...

What'd you clean the pots with? How'd you clean the pots? Though you're correct that is a good one to practice on, it's probably next to impossible to find a service manual, so that might hold you back.
 
To answer the question in the header of your post, No capacitors are not likely the issue.

This old brain seems to recall something from the past. Did you clean the 8 Track record play switch?
 
Hajidub said:
What'd you clean the pots with? How'd you clean the pots? Though you're correct that is a good one to practice on, it's probably next to impossible to find a service manual, so that might hold you back.
Click to expand...

I used WD-40 contact cleaner. Not the fabled de-oxit, but it worked well on another receiver I cleaned up previously. Sprayed in the little hole and did a bunch of spinning. Yeah, you're probably right about the manual.

AE Bob said:
Did you clean the 8 Track record play switch?
Click to expand...

It doesn't have an 8-track record feature, but I did clean the input switch.
 
The schematic would be helpful. The power supply is working correctly ? passed DBT test ? You did clean the pots and switches correctly ,right? Look inside to see if there are IC's in it ,be a tuff fix if there are. It might be old enough to be all transistors then I would start at the speaker terminals and look for the output transistors and check them.
 
Don’t waste anymore time with wd40! Deox only. If you’re gonna get into this hobby seriously, don’t be cheap with tools.
 
The WD-40 is not conducive and it displaces water. I don’t think it would cause the issues your seeing.
Caps. Maybe
What outputs does that use?
I might have a scat for that.
For three bucks! That is some serious fun. How could you go wrong?
AUX input? I would try a different input. If you can. Like a CD player an see if the amp is the issue.
If I can find time I’ll look into this cool contraption.
 
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