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Pioneer SX-580 No Audio with power right power meter on max

SoulBowl

New Member
Hello,
I have a pioneer SX-580 that has been working for years. Recently the speakers stopped working and it seems that only the left A channel works.

The two 4A fuses were blown and when replaced the watt meters jumped around and the right one stayed just over half way.

The power ICs were tested and Q2 has pins 1,3,5 shorted and pins 7,8 shorted. Q1 looks ok.

I removed the power IC's and inserted a 1kohm between 1&3 and 8&0. The following are my readings:

Q2:
0: 0.85v
9: 28.6v
8: 0.22v

3: 0.22v
2: -28.8v
1: -6.02v ***

Q1:
0: 5.61v ***
9: 28.6v
8: 0.15v

3: 0.01v
2: -28.8v
1: -5.58v ***

It looks like C314 and C313 might be shorted. These are the readings of each to ground:

C314:
+: -26.6v
-: -27.5v

C313:
+: -26.8v
-: -27.4v

When powered up after sitting for a while I hear a pop. It will not pop when powered on and off after shorter periods.

Please let me know if you have any ideas? Let me know if you need any more measurements or anything to help out. I love this amp and would love to get er going again.

Thanks very much.
 
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