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(Solved)Repairing sony STRDE-597 amplifier

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fezder

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Okay, got this from buddy, obviously would like it to be repaired.
Luckily, this thing doesn't seem that complicated. Fault was simple to describe, magic smoke escaped when device was used about 45 minutes, source wsas analog input. Now then, interesting is that when I opened thing, is that one IC is completely, no there, has been soldered away. And, next to where-should-be-amplifier-ic, are two end-amplifers, and other has been repaired sometime ago it seems because there is very funny attempt to create isolation between heatsink and transitor flange; piece of PLASTIC BAG. This bag piece has slowly "melted" and hence transistor has shorthed to heatsink...yup, at least one reason of smoke was found.

I tested with lamp-cord that device tries to turn on (I hear relay click when I plug mains on, as well when I press standby/power, so it tries to do something)
Since this was found from internet, here's service manual:
http://sportsbil.com/sony/STR/STR-D/STR-DE597_v1.0_.pdf
IC that is missing is marked IC571, and transistor that has blow is MN2488, to give location glues
and picture of that interesting place(SB amp board, surround back):
IMG_1390.jpg
Customer said that full-surround isn't needed, 2.1 is enough.
Tips welcome! I'll start by checking condition of 'lytics & bigger transitors, and voltage rails for start.
 

fezder

Well-Known Member
Taking surround speaker system pcb out and then using didn't make difference, and couldn't find any faulty components apart from those first ones. Off to measure voltages. And I do use isolation transformer, even though this uses transformer. Also, I noted that display doesn't show anything.
 

fezder

Well-Known Member
Lol, forgot obvious, fuses. Indeed, main fuse was blown. No wonder it didn't do anything....well, I quess everyone stumbles on small rock too.
 

fezder

Well-Known Member
removing surround back-module and new fuse fixed it :)....did test speaker as dummy load before real speaker
 

fezder

Well-Known Member
Argh, yesterday I used amplifier many hours and it worked flawlessly. Now that I tested it, blew fuse. customer suggested to place bigger fuse...
I said that you replace bigger fuse if you wan't but I won't do it. So, it was returned to customer, hopefully he won't change bigger fuse, that won't do any good. But, It's not mine responcibility what if.
 
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