PLEASE Help me fix my receiver.

Michael87212

New Member
I read all over the internet about recapping receivers and how great it makes them sound. I thought my pioneer sx 680 would be a great candidate for this. Unfortunatley the internet had me fooled on some basic capacitors facts. That increasing voltage and uf doesn’t affect the system negatively (I now no this is not true). So I did this to each one of my new capictors (Elma capacitors from parts connexion) cleaned the board wil some deoxit and isopropyl alcohol, turned it on and... it didn’t work. The audio could still be heard but with a large buzz on both channels that could damage speakers if played for long enough. Does anyone know anyone someone or somebody who would be able to fix something like this. I have lots of paperwork and tons of schematics on it.
 
If you made the replacement yourself you should be able to reverse the work with the correct value components.
 
How far away from the originally uF did you use for the replacement caps?. As far as I know higher voltage caps should have no effect ( except on cost ) but greatly increased uF can, but I'm not convinced that is the cause of the buzzing.
 
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The audio could still be heard but with a large buzz on both channels that could damage speakers if played for long enough.
Could be dc voltage causing the buzz. Maybe make up a list/spreadsheet of the cap number (Cxxx) the old uf/Voltage and the new uf/Voltage.
Maybe identify a few to change back, however I'm with @kaplang that the buzzing might be caused by something else.
 
It's very possible that more than a couple capacitors are in backwards. I'd go back over each one and pull, check orientation against the board markings (there is at least a + sign on each cap placement), re-install correctly.
 
As larryderouin says, correct capacitor polarity is absolutely critical, as is good soldering (no bridges between traces, no cold joints, etc).

I've never seen/heard anyone claim that capacitance (uf) is unimportant. Amp circuits were designed to operate with the values they were built with. Yes, some people with good electronics design skills and an understanding of the circuits may come up with good modifications for a particular amp that may involve different capacitance values for certain caps. But simply using any value cap at any point in the amp would be disastrous. Stick with the values that were there.

As for voltage rating....just make sure it is equal to or higher than the original. Too low and the capacitor will be damaged (and perhaps other components in the circuit). In most applications, they are only too high when they become too large to fit, or too expensive (or both).
 
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I read all over the internet about recapping receivers and how great it makes them sound. I thought my pioneer sx 680 would be a great candidate for this. Unfortunatley the internet had me fooled on some basic capacitors facts. That increasing voltage and uf doesn’t affect the system negatively (I now no this is not true). So I did this to each one of my new capictors (Elma capacitors from parts connexion) cleaned the board wil some deoxit and isopropyl alcohol, turned it on and... it didn’t work. The audio could still be heard but with a large buzz on both channels that could damage speakers if played for long enough. Does anyone know anyone someone or somebody who would be able to fix something like this. I have lots of paperwork and tons of schematics on it.

Please list the capacitors you replaced and what values the new ones have, part numbers of the replacements would be the best response.


Welcome to the Pioneer audio forum, wish it was under better circumstances.

Our motto is that there are NO stupid questions, and dumb is defined as forging on ahead when one is not sure of exactly what to do. "Trusting the force"... We all have been at where you are at, with enthusiasm, and have survived it, lol. We're all guilty of some zingers, so welcome to the club.


I hope you were aware that electrolytic capacitors have polarity and that installing with correct polarity is CRITICAL, because when installed backwards the electrolytic capacitors are dead short circuits? That sounds suspiciously like what has happened.

Stuff happens, let's get your SX-680 up and singing.

If you are unsure - ASK, and post pictures....
 
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btw, welcome to the board, and a future note for replacement: align the 'new' capacitor the same way the 'old' one came out. you have seen above why, but DO NOT TRUST the screen printing on the board. I 3 step verify...
1) put in the way it came out
2) verify the way if came out jives with the screen printing on the board and make notes in the SCM if wrong
3) verify the screen printing jives with the actual schematic (SCM) as sometimes IT can be wrong too.

The theory being, if it works when you get it, whatever is installed is right therefore any documentation is suspect until verified.
 
When replacing electrolytic caps, you can safely increase the voltage, but some caps have special uses in the circuits, like high pass filters, and you have to know how the cap is used before changing the capacitance.
Having said that, very low audio on both channels and hum sounds like you got at least 2 caps in backwards. Sometimes the silk screen markings on the board are wrong and you have to look at each cap before you remove it, and put the new on in the same way.
 
When replacing electrolytic caps, you can safely increase the voltage, but some caps have special uses in the circuits, like high pass filters, and you have to know how the cap is used before changing the capacitance.
Having said that, very low audio on both channels and hum sounds like you got at least 2 caps in backwards. Sometimes the silk screen markings on the board are wrong and you have to look at each cap before you remove it, and put the new on in the same way.

It sounds as if it's a bit late for that...his options now seem to be the schematic and the board markings. If those two agree, chances are good they are correct. If they don't agree, more investigation of the circuit is required
 
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