I'm not saying that there are no exotic capacitors in exotic circuits that need some sort of run-time to reach whatever but capacitor burn-in time in general audio circuits is nonsense.
It sounds like you has some electrolyte contamination that wasn't completely cleaned up. It could resolve itself but will more likely need some more work to get the electrolyte cleaned up, if that's the problem.
It's also possible that there are bad solder connections, dirty contacts on pots/switches or on a connector. Initially, lightly touch any of these to see if you can make the problem better or worse.
It sounds like you has some electrolyte contamination that wasn't completely cleaned up. It could resolve itself but will more likely need some more work to get the electrolyte cleaned up, if that's the problem.
It's also possible that there are bad solder connections, dirty contacts on pots/switches or on a connector. Initially, lightly touch any of these to see if you can make the problem better or worse.
That is kind of what I figured. Lots of snake oil out there for sure. I just wasnt 100% on it. I saw a guy yesterday trying to sell speaker wire for $2k because it was "special". It was only about 30 ft of wire.
I thought I did a pretty thorough job of cleaning, but its certainly possible I missed something. That crap gets under all kinds of things.
Im pretty decent at soldering (used to build stuff for Physio Control about 30 years ago), so I like to think my soldering isnt the issue, but Im not too proud to state it couldnt be. Ill take a peek at the pots.
After listening to it today, it seems one side of the amp is having the issue and I am pretty sure I know what side that is, ha. Hopefully, it will resolve itself, but im not confident. At least its sort of working now, so thats much much better than when I started. Thank you again for your help and patience!
I thought I did a pretty thorough job of cleaning, but its certainly possible I missed something. That crap gets under all kinds of things.
Im pretty decent at soldering (used to build stuff for Physio Control about 30 years ago), so I like to think my soldering isnt the issue, but Im not too proud to state it couldnt be. Ill take a peek at the pots.
After listening to it today, it seems one side of the amp is having the issue and I am pretty sure I know what side that is, ha. Hopefully, it will resolve itself, but im not confident. At least its sort of working now, so thats much much better than when I started. Thank you again for your help and patience!
If you go back into it, acetone is far better than rubbing alcohol for cleaning flux.
A couple of notes...
Acetone will take the markings off of through-hole resistors where alcohol will be less likely to do so.
You can often take your scope probe (use the 10k probe setting and a low-voltage on the scope's vertical amplifier) and probe around on the board. The trace should never deflect when not on a trace. If it does, there is likely electrolyte present.
Don't you know that you must have tin-plated eardrums if you use anything other than pure silver speaker wire with a Teflon insulator with the two strands (positive and negative) separated from each other by 6 inches and also lifted off the floor by the same amount... Then have an impedance compensating network at the speaker end of that wiring. If you don't have all of that, you may as well be listening to an old AM Bakelite radio.
A couple of notes...
Acetone will take the markings off of through-hole resistors where alcohol will be less likely to do so.
You can often take your scope probe (use the 10k probe setting and a low-voltage on the scope's vertical amplifier) and probe around on the board. The trace should never deflect when not on a trace. If it does, there is likely electrolyte present.
Don't you know that you must have tin-plated eardrums if you use anything other than pure silver speaker wire with a Teflon insulator with the two strands (positive and negative) separated from each other by 6 inches and also lifted off the floor by the same amount... Then have an impedance compensating network at the speaker end of that wiring. If you don't have all of that, you may as well be listening to an old AM Bakelite radio.
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Thanks for the tip. I used acetone on another board the other day and the letters and such started coming off. That had me a little concerned.
Good to know on the scope probing. Feeding it 1khz, or something? I assume that would make for a more stable reading than audio tracks.
Hahaha!! I have my wires smuggled to space so they can be assembled in oxygen free environments and sealed on the ends with dragon tears (new tech). They are also UV tested in that process. Sounds fantastic! Let me know if you are interested. Since this is a costly production, only $4M per foot. Quite a bargain!
Good to know on the scope probing. Feeding it 1khz, or something? I assume that would make for a more stable reading than audio tracks.
Hahaha!! I have my wires smuggled to space so they can be assembled in oxygen free environments and sealed on the ends with dragon tears (new tech). They are also UV tested in that process. Sounds fantastic! Let me know if you are interested. Since this is a costly production, only $4M per foot. Quite a bargain!
I'm fresh out of dragons' tears so if I come up with about $80M, I'll get back with you.
You don't generally need a signal. The DC will leak (electrically through the electrolyte) and you will see that. That said, try it both ways to see what works best. I don't know if a sinewave would be as good. Some frequencies may pass through the electrolyte better and if so, the audio (being more complex) may show up better.
You don't generally need a signal. The DC will leak (electrically through the electrolyte) and you will see that. That said, try it both ways to see what works best. I don't know if a sinewave would be as good. Some frequencies may pass through the electrolyte better and if so, the audio (being more complex) may show up better.
Ok, well let me know if you need special cables!
thanks for the further help. If it doesnt remedy itself, ill pull it back out of the car and back on the bench. I feel like this amp needs to start making my dinner for all the money and time Ive spent on it.
thanks for the further help. If it doesnt remedy itself, ill pull it back out of the car and back on the bench. I feel like this amp needs to start making my dinner for all the money and time Ive spent on it.
Ok, so a little that I have observed and thought I would post before I dive back in. Channels 1/2 are the problem side of the amp. Im pretty sure thats the side that had the grounding problem and the worst corrosion and burnt resistors. Power up and both speakers offer a bit of static once the relays are engaged. Then it fades off and those channels produce no audio until there I up the volume to near maximum from the source head unit. Then it cannot decide which channel to run. Sometimes the left one, sometimes the right one, but only with the input volume near max or at max. Initially, I was thinking maybe one of the preamp boards (one had more corrosion than the other) might be the culprit, but since it happens to both channels, im not sure about that assessment. Im pulling it out of my car tomorrow and back on the bench it goes.
That sounds like a dirty switch or contact. The audio can't break through the oxidation until the signal reaches a certain level.
I did turn the gains and move the switches, but I didnt (foolishly) do this when it was on. That would be an easy fix!