Phoenix Gold MS-2125 no rail voltage

Yes, that transistor was shorted. I replaced it and the DC voltage was at +10v on pins 13 and 15. Also had rail voltage. noted that only the 2 LED's on the right channel were lighting up. After shutting the amp down and powering it up again later none of the LED's in the audio section were lighting up and voltage on pins 13 and 15 has dropped to -0.075 although it still has rail voltage...
 
I have remote power. I pulled the transistor and it checks good.

The power LED is coming on. In the attached photo I circled the LED's in the right channel audio section that were previously illuminating as they should but stopped.

Prior to this happening, I had noticed some solder traces that were dangerously close to touching in the audio section of the right channel. I cleaned those traces up and I'm thinking something may have shorted in the process. The caps on this amp seem to hold a charge for sometime.
 

Attachments

  • 20191115_141822-1.jpg
    20191115_141822-1.jpg
    1.1 MB · Views: 56
See attached photo for DC voltage readings across the 4 LED's.


The supply voltage across the B+ and ground terminals of the amp is +10.8v


DC voltage of PS driver IC:
1. +0.001v
2. +2.15v
3. +0.20v
4. +0.497v
5. +2.022v
6. +3.623v
7. +1.942v
8. +4.81v
9. +6.19v
10. +0.008v
11. +4.05v
12. +0.001
13. +10.77v
14. +4.05v
15. +10.77v
16. +5.06v
 

Attachments

  • 20191115_141822-2.jpg
    20191115_141822-2.jpg
    924.5 KB · Views: 36
I'm not sure what is pulling it down. There is almost a 2v drop between what the power supply meter is showing and the reading at the amp terminals. I turned it up voltage at the amp terminals is now 12.2v


I'm guessing you are refer to one of the opto-couplers that are to the right and left of the PS driver ICs...


DC Voltage on the opto-coupler on the right in the photo in #14:
1. -2.1v drops very rapidly
2. -2.1v drops very rapidly
3. -0.002v
4. +2.52v
5. +5.06v
6. +3.19v