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Weak outputs transistors Sansui 9090db

mr.b1274 said:
No off and then back on goes green ,then into protect
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It goes into protect for a reason. Replacing components willy nilly (again) will not get you a fix. What is the output voltage of both channels before the relay? If it has DC on it it will go into protect. Fix that and your issue is gone. If it doesn't have DC on it your protect circuit has a fault but those cases are rare and usually caused by a bad cap. Or leaky transistor.
 
So now so close but it is not giving me dc readings or ma for that matter.but protection issue is resolved,gives me AC mv, at emitters,how I settled it down is worked backwards of A biased 9090db all the way back to trimmers and noted their ohm settings used those settings no more protection, but she ran ice cold gave AC milla volts of 5.1 both sides ,get nothing at the fuse holder used two different good meters.maybe need to go higher on trimmers.not sure.it powers up quick though.and dim bulb test was perfect bright then click,down to nothing.even powered up quick on dim bulb.it might be that rectifier mod maybe.that's why I went to emitters its kinda like biasing while blind.
 
mr.b1274 said:
So now so close but it is not giving me dc readings or ma for that matter.but protection issue is resolved,gives me AC mv, at emitters,how I settled it down is worked backwards of A biased 9090db all the way back to trimmers and noted their ohm settings used those settings no more protection, but she ran ice cold gave AC milla volts of 5.1 both sides ,get nothing at the fuse holder used two different good meters.maybe need to go higher on trimmers.not sure.it powers up quick though.and dim bulb test was perfect bright then click,down to nothing.even powered up quick on dim bulb.it might be that rectifier mod maybe.that's why I went to emitters its kinda like biasing while blind.
Click to expand...
Check the internal fuses of your meter(s), it is easy to blow the low mA fuses and then you will get no readings on that scale.

I usually start on the high amps setting and once I know the power draw is at a safe level I then switch to the low mA scale for better resolution.
 
mr.b1274 said:
gives me AC mv, at emitters,how I settled it down is worked backwards
Click to expand...
It sounds like you are using your AC range to measure DC voltages? - is this what you are doing? - if so, this will give very inaccurate results.

mrk229 said:
Check the internal fuses of your meter(s), it is easy to blow the low mA fuses and then you will get no readings on that scale.
Click to expand...
:thumbsup:
 
Update ,all is well,it was a bad loudness switch with a crunched contact.and a few other things ,like nobody calibrated Dolby board after restore it was way off,I did have a friend help me figure out biasing issue ,he said it was the mod the other tech did,he pulled the bridges and made reading at fuse holder inert.we did it at emitter using scope.it sounds very very good now and since I spent hours upon hours on Dolby board and then the other guys did also? I use the rec 1 setting it sounds amazingMessenger_creation_174A3CA2-9DB0-49CD-97DA-A26820CBD573.jpeg
 
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