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Pioneer qx949A

M

Mcintosh N

AK Subscriber
Subscriber
Need help, I have been struggling for few days on the power supply of the pioneer QX949a and can get any relay click.
I can’t get any voltage on Pin 20, it supposed to be 30v and I get 280mv.
I lifted the pin 20 and no voltage is coming out of the pin 20.
Q4 ( 2sd525)
B 226mv
E 279mv
C 0.64v

That feeds the power supply and relay.
I changed everything on the board, capacitors, transistors were checked, and diodes and Zener were also check, all tested fine.
Could the relay may be the cause?
 
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This is what I done on the power board awr080
All new capacitors
Replace Q2, by ksc2690
Q3 by ksc1845
Q6 by ksc1013
 
Is the bulb bright? Pin#20 feeds the power amp boards and the control board. If you disconnected Pin#20 you may need to disconnect the rest of them to isolate that board AWR-080. It could be that the unit is in protection because of a blown output transistor(s)
 
Its Pins #1 and #2 on the protection board AWM-079, that will only help you if the relay coils are shorted . Pulling all the output transistors might be the way to go . I think its in protection mode ,I would look at the amps . I'm not a Tech but I did a full restoration on the QX949 there's a lot going on in there.
 
No click but could not find any shorted or bad transistors.
I am measuring the protection relay board,
1 and 2 are powering the relay and with the wire removed I get 1v definitely not enough to power the relay, all the voltage are wrong on this board!
 
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