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Pioneer SA-7800 sound problems

transistors might still be ok . they all need testing as something is drawing too much current through those resistors you mentioned
 
Well, sure enough, output transistors are dead... I dont know what caused it but they were not dead in the beggining of the day so... good job me... I should have waited for that trimmers maybe it is what caused it...
 
all parts must be in good shape as in testing within tolerance .
bias trimmers turned right down .
all power supply voltages must be good .
this design amplifier is not forgiving at all .
always use a DBT until you know everything is working properly . it should save the output transistors from blowing up .
 
yeah, learning the hard way :) but you know, experiences will come with repairs i will do...

Should i replace both channels now?
 
So, I was finally able to get back to this I replaced the power transistors on output, I replaced trimmers and few resistors, I started to getting transistors around amplifier out... And i have more bad news for me - some of them are a little tired lightly speaking... But I was looking around this forum for replacement types and I found zero, nothing, well i found replacements in few threads but only replacement i was able to obtain is KSA992 and nothing more, all the parts are obsolete now... Any tips and tricks on how to find some other replacements, or does anybody has any tips?
 
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And one more question - service manual says setting should be done with trimmers counter clockwise which means basically 0 ohms? Is that right? I dotn want to blow my power trannys again, i dont have original trimmers, i already threw them away month ago :)
 
Gobstoppper: I appriciate your help very much, but I did see that and I am ordering from mouser even in EU. But most of transistors are obsolete and even their replacements are (no kidding! they are just out of stock everywhere)... I am now trying to find someone with salvaged parts in working condition and I will probably be successful since I know one guy who repairs pioneers... Fingers crossed. The amp is so beautiful, would love to have ti working already :)
 
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