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Pioneer SX 980 - Blow up fuse

Verify Q2 KSC2690 installed correctly as the leads are ECB while 2sc1438 is BCE.

Ignore ^^^^ both are ECB!
 
Last edited:
Frederic73 said:
here we go

Thanks for all your help

pin 1 21.40 v Ac
2 -49.60 v
3 0v
4 12.79v
5 0.149v
6 0.103v
7 0.067v
8 0.021v
9 13.22v
10 68.6v
Click to expand...
These look OK, however there is 149mv DC on right channel output. Amplifier adjustments on page 25 of service manual, center voltage and idle current, should be performed at some point.
 
OK. Check that C1 is installed correctly.

48V on coil and 0V+- on pin 4 of PA3004 relay should be engaged (out of protection) as I see it. Someone else with more experience with this protection circuit may want to add/correct this assumption. Given that there is only 13V on coil it seems either the coil or D3 at this point.

If excessive DC is causing the issue, disconnecting pins 4, 5 and 8 on protection board will disconnect outputs from the circuit and the relay should click.

You can check this thread: https://audiokarma.org/forums/index...80-protection-relay-kicking-out.834334/page-6
 
mcdoug3721 said:
OK. Check that C1 is installed correctly.

48V on coil and 0V+- on pin 4 of PA3004 relay should be engaged (out of protection) as I see it. Someone else with more experience with this protection circuit may want to add/correct this assumption. Given that there is only 13V on coil it seems either the coil or D3 at this point.

If excessive DC is causing the issue, disconnecting pins 4, 5 and 8 on protection board will disconnect outputs from the circuit and the relay should click.

You can check this thread: https://audiokarma.org/forums/index...80-protection-relay-kicking-out.834334/page-6
Click to expand...
Thanks for all your help, should i remove the relay and give it a good clean ???

C1 is good
 
Relay may be shorted or bad. It can be tested out of circuit with 48V DC across the appropriate pins.

I would disconnect pins 4, 5 and 8 on protection board as a final test. This will disconnect the amplifier outputs and any DC voltage there may be. You have 145mv on one channnel which is high but not high enough to prevent the relay from engaging in my opinion. If relay clicks, you need to address the DC offset by preforming the amplifier adjustment procedures. These procedures need to be done once everything is sorted out regardless.
 
mcdoug3721 said:
Relay may be shorted or bad. It can be tested out of circuit with 48V DC across the appropriate pins.

I would disconnect pins 4, 5 and 8 on protection board as a final test. This will disconnect the amplifier outputs and any DC voltage there may be. You have 145mv on one channnel which is high but not high enough to prevent the relay from engaging in my opinion. If relay clicks, you need to address the DC offset by preforming the amplifier adjustment procedures. These procedures need to be done once everything is sorted out regardless.
Click to expand...
Disconnected pin 4, 5 and 8 and still no click . So it must be the Relay .
 
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