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Sx-650 going into protection when turning up volume.

I looked up the caps. They are polarized. They should be fine UNLESS they were reversed.
The usually recommended film caps go in and they are not polarized.
A backwards electrolytic cap looks like a short circuit. But it takes some voltage to activate the chemistry and start acting like a short circuit..
Pioneer laid a lot of traps for cap reversal between silk screens, pc board patterns and paper documentation.

I looked up the two caps C21 & C22 up, they are side by side in about the exact center of the vertical GWR-101 board.
Their positive leads go in the holes closer to the 220uF C26 and the R59 (68 k ohms blue gray orange gold)
The manufacturer marks their NEGATIVE lead with a black band.

PLEASE CHECK THEIR POLARITY CAREFULLY!!!!!

ok, bunch a dumb questions:
You owned it for a few months and then did the refresh. This didn't do it before the refresh?

Try turning up the volume with no audio present (like phono or aux) but the speakers on, does it do it without audio present?
 
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As per your last post I checked all caps against the schematic and silkscreen on the board and they were correct.
Still could not get my head around why it would work with D7 removed, so I started checking voltages around that area and found 25a823 was way off. desolder it and when I removed it the collector leg stayed in the hole. used needle nose to pull out leg which was not stuck in the hole.
Replaced with KSA992FBU and she is singing again at full volume. In fact the queen of evil is upstairs yelling at me to turn it down.

I really do appreciate all your help. You pointed me to the area I needed to scrutinize.
@AE Bob , That goes the same for you.
Thank You very much.
 
I am glad that this fault has finally been unearthed. enjoy... :music:
It was a real head scratcher.


D7, D8 and D9 are in a "wired OR" configuration,

the diodes keep D7 from interfering with D8's and D9's circuits
the diodes keep D8 from interfering with D7's and D9's circuits
the diodes keep D9 from interfering with D7's and D8's circuits

yet any one of the three can signal a shutdown, by pulling the 2sa823 BASE low.
(without upsetting those other parts of the sensing circuit.)
 
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