Need some help with a Technics A900s

hi.

i have received my second Technics se-a900s, i bought this one defective, the problem is that it is in protect. i had a hope that it could be bad solder points... so i started troubleshooting yesterday and found many bad solder joints... soldered these but nothing happened, so i went ahead and measured some volts on svi 3205, and on pin 3 i found the fault.. 53.2v..so the left channel is defective.. i have an a800s that looks like it has been through a meat grinder so i am thinking of taking the svi 3205 from this one, but i don't want to put it in without knowing what caused the svi3205 to fail. so what is the next step? are there any other components that could have been damaged?
 
If pin 3 is +52v then pin 15 of IC502 will be at +52v.
Hopefully it is not damaged.
I would remove both ICs, check any component is the vicinity with a triangle mark next to it, that should determine any other issues.
Fit new ICs and hope fully that will be that.
IC502 may have survived but that depends on how long it has been run under fault condition.
 
If you build a copy of the amplifier on a bread board, you can test the ICs but I wouldn't go to that expense; components, heat sinks, power supply etc.
Okei, but what I don so far is de solder the svi3205 and taken of the cover.. I found a burned track on top that’s leads to pin 3..
 

Attachments

  • IMG_9964.jpeg
    IMG_9964.jpeg
    680.4 KB · Views: 36