STR-DE975 burn my speakers on the right Channel

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PogoSoft
STR-DE975 burn my speakers on the right Channel

Hi,

 i have some problemes with my Sony STR-DE975. The problem began with my rear right speaker who burn when i plugged it. The receiver start after a couple of second and i notice a burn odor from my left right speaker. I tried the left speaker and it did the same thing exept that i remove it before it burn. I remove the speaker and use only the front speaker for a couple of months. The front speaker was working fine exept when i put the sound past 32, the sound was distortionned. Yesterday when i start the receiver, there was nothing on the display and i heard i loud sound and before i have the time to close the receiver the right front speaker burn.

Is it possible there is a problem with the power Amp (UPC2581 ) or should i check other parts ?

Thank you !

Pierre

dans_repair_service
First of all hte upc2591 is

First of all hte upc2591 is not the power amp.  It is part of the amp section.  There are probably 3 of these inside the unit.  It would appear that you have a combination of open outputs +/or shorted components in the pre-driver section.  THe distortion could be from you attempting to driver the speakers from the driver stage rather than the output stage.  The speakers are burning up because you have DC voltage on the outputs.  You apparently also have a problem in the protection circuitry since any DC on the outputs should place the unit into protect mode.  This is not a repair that can be done by a novice.  Sony's design is such that a number of items must be done at the same time to prevent further damage. 

I have repaired a number of units in this series and the cost can add up to $150 with parts and labor.  Since you have multiple problems,you might be headed close to the $150.  The UPC2581 chips run about $12-$15 each.  Add in the outputs @$4-$6 each and you get up there quick.  I believe that the surround channels are powered by a 5 pin "output pac" whose number I don't recall at the moment.

I'll look in my records to see if I can provide any additional (hopefully encouraging) info.

Dan

PogoSoft
Hi Dan,

Hi Dan,

 thank you very much for your quick answer, i got the service manual in hand. If you want to take a look i can send it to you by email.

 Pierre

 

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