Hello everyone.
I have this Sony amp and it powers up sometimes, but sometimes blows the fuse. When it does power up its not drawing hardly any current, like its not on all the way. The "OFFSET" light it stuck on and the amp has no output. Does anyone know what would cause this light to be on?? I have read up on how spendy and hard the output fets are to buy and find.
Any advice would be great......Thanks.
I have this Sony amp and it powers up sometimes, but sometimes blows the fuse. When it does power up its not drawing hardly any current, like its not on all the way. The "OFFSET" light it stuck on and the amp has no output. Does anyone know what would cause this light to be on?? I have read up on how spendy and hard the output fets are to buy and find.
Any advice would be great......Thanks.
I resoldered the buss bar even though it looked ok. Still same thing. Upon applying remote voltage lots of current draw then "OFFSET" light comes on and current draw goes away, and amp remains powered on. I called the guy who owns it and he said the ground was shorting where he had it hooked up. Could a bad ground arcing have taken out 1/2 the power supply or some output fets? I dont know much about Sony amps so I really dont know which direction to go.
That amp is a BEAST, I got one for cheap a while back and did some repair on broken traces around the speakers leads (board broken completely through) and some other cracked solder joints and it rocked. I sold in on ebay and didn't get squat for it, probably should've just kept it. 
Sorry for the interruption.... as you were :lol:
Sorry for the interruption.... as you were :lol:
I dont see a pulse of DC but one of the bridging terminals starts out with like 6.50 vdc and slowly bleeds down.
I have not checked the output fets yet. I will have to remove them from the circuit to test them correctly right? I would think if they were shorted I would have full rail voltage on the speaker outputs? I am not very familiar with sony amps, never liked them just trying to help out a friend.
I dont know where the driver transistors are on the board as I said I am very unfamiliar with Sony amps. I found a spot on the board that is darkened brown. Two resistors just above the transformers, R937 and R938. There is a what looks like a small IC which is IC 903 on the board. What are the purpose of these resistors and IC?
The resistors are pulldown resistors for the power supply FETs.
The IC is an opto-coupler used for voltage regulation of the rails.
I don't know which channel is defective (which one is it) so, both channels are marked. The drivers are circled. The rectangles are the VAS transistors. Check them also.
The IC is an opto-coupler used for voltage regulation of the rails.
I don't know which channel is defective (which one is it) so, both channels are marked. The drivers are circled. The rectangles are the VAS transistors. Check them also.
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