electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
Sony STR-DE435 repair issues

 
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
pelekkk
Guest





PostPosted: Thu Aug 16, 2007 3:24 pm    Post subject: Sony STR-DE435 repair issues Reply with quote

Hi,
my brother damaged this amp by accidentally connecting speaker cables. I already found that MN2488 and MP1640 transistors blown (output, darlingtons) and that one double-resistor (0.22 ohm, 5W) is open. From what a friend told me, preamplifier IC (uPC2581V) can be blown. Is there a way to check if it's any good? I'm not a pro, just know basic of electronics Smile
Cheeers
pelekkk
Back to top
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Thu Aug 16, 2007 8:49 pm    Post subject: Reply with quote

That rings a bell.... While the UPC may or may not be bad, there is no concrete way of testing other than standard check for shorts between pins. (as a rule, you can use one of the other UPC's from a known good channel to use as sort of reference without having to pull it)

If/when those UPC's are damaged, you'd read a dead short between pins & most of the time they'd crack open.
Back to top
View user's profile Send private message
pelekkk
Guest





PostPosted: Sun Sep 16, 2007 12:07 am    Post subject: some other issues Reply with quote

OK, so I fixed what I could. There was no shortage between legs in this IC, so I assumed it's good.
I've put everything together, screw all the screws and this is what I've got:
When I plug the power chord, amp turns on (and it should go to sleep mode, wright?), on display there is "ALL CLEAR" and after 2-3 secs everything is on. Seems like amp is working, but none of the buttons in front is working (except for two: power buttun and that knob that has A-B-AB-OFF speaker selection).
What can be wrong? I checked all the connections, all relay are clicking, just those darn buttons...
Cheers!
Back to top
vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Sun Sep 16, 2007 3:07 am    Post subject: Reply with quote

The "all clear" should come up when the unit is being reset! So if you are absolutely sure nothing is left unplugged/etc., then sounds like there may be a system control problem also which means more troubleshooting preferably with a scope. ----just make sure none of the pushbuttons are accidently jammed?
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Page 1 of 1

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


eServiceInfo on FB - Service Manuals Free Download - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Service Manual Search - Jabse.InK  - onTap.bg

SnimkiOt.com - Poblizo.com : пътешествия