Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap?

[Deses]

Hi everyone!

I'm taking a look at one vintage piece of equipment from my dad, a nice Pioneer SA-510 straight from 1980. It has been inside a box for the last 10 years or so and today I tested if it turned on and it sure did! But the stereo sound is a bit wonky, I have to wiggle the audio jack to achieve stereo sound, the audio pops when turning the volume and it very distorted.

I then opened the chassis and I didn't see anything really wrong apart from a capacitor with a black stripe o the top. I'm not sure if that's just black marker or fluid leak. Here are some pictures. It looks marker to me, but other pictures of the board I found on the Internet doesn't show that so I'm really not sure. But then again those are really old Japanese caps from before the capacitor plague, sooo probably marker, yeah.

Here's the board diagram if anyone is interested in that. The cap I'm talking about is in Page 5, square 3-A, C54.

About the knobs making noise when turning, I guess my best bet would be resoldering the potentiometers or replacing them?

I really don't know where to begin with this or how could I identify the problems, so any help is appreciated!

[stj]

Re: Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap

you need to clean or replace the pots, switches etc.

i cant tell you the caps are fine, but a black line is marker.

[Compgeke]

Re: Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap

Pots and switches for sure. Pick up some Faderlube and that'll work wonders on the pots. If you can't find that, I've found Deoxit D5 works alright usually, however stronger ones will eat the carbon traces.

I've fixed at least 10 amps\receivers that have the same problem you described and is almost always just a good cleaning. The few exceptions are 60s gear that should be recapped even if it worked right.

[montemcguire]

Re: Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap

Pots and switches often get 'crunchy' when there's DC passing through them, which happens when the electrolytic coupling caps are ancient and leaky, and fail to block DC from the switches and pots. Before you put a huge pile of possibly damaging gunk into the pots and switches, replace all of the electrolytic coupling caps. They're from the Ford administration - they're not expected to work anymore. Modern caps work better anyway.

The good part is that, while the switches and pots are impossible to replace, the electrolytic caps are actually easy to replace. Please do that, since you cannot replace the switches and pots, and they are probably not bad anyway.

Best of luck!

[stj]

Re: Pioneer SA-510 finicky stereo sound, lots of popping noise and a possible bad cap

you would be surprised about a lot of switches & pots - most are still production designs.