Fan issue Adcom GFA-5800 bias too high?

ben62670 · 13th April 2008, 11:31 PM

Hey guys. I am having a cooling issue with a GFA-5800.
I am helping a friend out, and here is what he has reported.
"After being on about 20 minutes my right fan header measures 3.8v and the left is 3.2. At this point neither fan shows any signs of life.
I'm not sure what the bias procedure is for this amp, but measuring across R64, I get 45mv on the right and 56mv on the left."
Thanks
Ben

Anyone have the service manual?

sakis · 14th April 2008, 03:13 PM

before any advice in the 5800 ....

A)on the transistors of the out put are there hand writen letters in every one of them ????
B) is the amp about 10 years old ???

after that i ll let you know

ben62670 · 16th April 2008, 06:09 AM

There is no writing on the outputs, and yes the amp is about 10-15 years old.
Thanks
Ben

a.wayne · 26th April 2012, 06:23 PM

Quote:

Originally Posted by sakis

before any advice in the 5800 ....

A)on the transistors of the out put are there hand writen letters in every one of them ????
B) is the amp about 10 years old ???

after that i ll let you know

Welll ...?

13th April 2008, 11:31 PM	#1
ben62670 diyAudio Member Join Date: Dec 2006	Fan issue Adcom GFA-5800 bias too high? Hey guys. I am having a cooling issue with a GFA-5800. I am helping a friend out, and here is what he has reported. "After being on about 20 minutes my right fan header measures 3.8v and the left is 3.2. At this point neither fan shows any signs of life. I'm not sure what the bias procedure is for this amp, but measuring across R64, I get 45mv on the right and 56mv on the left." Thanks Ben Anyone have the service manual?

14th April 2008, 03:13 PM	#2
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	a few question ..... before any advice in the 5800 .... A)on the transistors of the out put are there hand writen letters in every one of them ???? B) is the amp about 10 years old ??? after that i ll let you know __________________ SERVICE ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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16th April 2008, 06:09 AM	#3
ben62670 diyAudio Member Join Date: Dec 2006	There is no writing on the outputs, and yes the amp is about 10-15 years old. Thanks Ben

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