Marantz 19 Receiver Bias Problem. - diyAudio
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Old 21st June 2014, 12:16 AM   #1
diyAudio Member
Join Date: Aug 2006
Default Marantz 19 Receiver Bias Problem.

I usually can fix anything. One channel biases perfectly the other channel has only 2mv of bias and does not respond to any change in the bias control.

I have checked almost every part.

The bias transistors on the good channel get very warm. On the bad channel they act like no current is being drawn.

I have a checked the string of output transistors that are biased and they are all good. The ampllifer plays just fine but very low bias.

The collector of q1204 is about .3 volts when it should be 1.2v

The collector of q1206 is about .7 volts when it should be 1.2v.

The collector of q1205 is at 38 volts when it should be at 2.5 to 10 volts
I checked q1205 and it tests fine.

The collector of q1208 should be at zero volts and it is at 7.6 volts.
I checked q1208 and it tests fine.

I am totally stumpted and am tempted to send it to a maranatz expert.

Thought I would give you guys a shot first.

Maybe someone could give me a procedure that might isolate the problem.

I will attach schemtics as soon as I can.

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Old 21st June 2014, 12:21 AM   #2
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Default Schematics

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