I don't know why I keep buying these things...
This latest one has me baffled. It powers up and the relay closes when run through a DBT, and seems to operate just fine (FM and AUX tested so far)
When plugged into the wall, no click.
The measured DC is ~40mv on both channels. I am doing most of the testing with the power amp unplugged anyway.
I have recapped both power supply boards (A & C), and have replaced all of the transistors on the A board.(the originals tested good) I used quality components, Panasonic FM & FC for the caps, Fairchild for the transistors. They are all installed correctly.
I have tested the voltages at the various pins on the A board - all test very close to spec EXCEPT for pin 5 - connected to the collector of Qk5 - which measures -31vDC where the spec calls for -23vDC. The voltages on Qk5 are: E -30.97 C-31.01 B-31.67. I have a feeling this is related to the problem. So far I have tested the following out of circuit: Rk4, Rk5, Rk10, Rk11,Rk12,Dk1, Dk3. All tested good. I even replaced the relay knowing full well that is not the problem, and it wasn't.
I read in a different 6600 thread that the emitter voltages on Qk1 and Qk5 need to be the same in order for the relay to close. On this, there is a diff of 8v.
Another interesting tidbit - the base voltage on Qk4 is .510v when plugged into the wall(no clickie), and .650v when run through the DBT. (60W bulb - relay closes)
Hoping someone can help me with this and thanks!
Edit - Here is a scan of the schematic - Power Supply "A" at the top - hope it's readable
This latest one has me baffled. It powers up and the relay closes when run through a DBT, and seems to operate just fine (FM and AUX tested so far)
When plugged into the wall, no click.
The measured DC is ~40mv on both channels. I am doing most of the testing with the power amp unplugged anyway.
I have recapped both power supply boards (A & C), and have replaced all of the transistors on the A board.(the originals tested good) I used quality components, Panasonic FM & FC for the caps, Fairchild for the transistors. They are all installed correctly.
I have tested the voltages at the various pins on the A board - all test very close to spec EXCEPT for pin 5 - connected to the collector of Qk5 - which measures -31vDC where the spec calls for -23vDC. The voltages on Qk5 are: E -30.97 C-31.01 B-31.67. I have a feeling this is related to the problem. So far I have tested the following out of circuit: Rk4, Rk5, Rk10, Rk11,Rk12,Dk1, Dk3. All tested good. I even replaced the relay knowing full well that is not the problem, and it wasn't.
I read in a different 6600 thread that the emitter voltages on Qk1 and Qk5 need to be the same in order for the relay to close. On this, there is a diff of 8v.
Another interesting tidbit - the base voltage on Qk4 is .510v when plugged into the wall(no clickie), and .650v when run through the DBT. (60W bulb - relay closes)
Hoping someone can help me with this and thanks!
Edit - Here is a scan of the schematic - Power Supply "A" at the top - hope it's readable
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