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-   -   Phoenix Gold MS-2125 no rail voltage (https://www.diyaudio.com/forums/car-audio/344988-phoenix-gold-ms-2125-rail-voltage.html)

Chopperbuilder 8th November 2019 06:02 AM

Phoenix Gold MS-2125 no rail voltage
 
Working on a Phoenix Gold MS-2125. It is not producing rail voltage.

I have replaced both SG2525A. The circuitry on this amp is a lot different than the amps I typically work on (Orion's). Anyone have any thoughts on what to check?

Perry Babin 8th November 2019 07:35 AM

Do you have 12v on pins 13 and 15?

Chopperbuilder 9th November 2019 01:31 AM

No. The DC voltage on pins 13 and 15 is +0.312v.

Perry Babin 9th November 2019 08:15 AM

Follow the circuit back until you find a transistor. Check that transistor or post the voltage on it's terminals.

Chopperbuilder 14th November 2019 04:56 AM

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...

Chopperbuilder 15th November 2019 07:24 AM

Perry, any thoughts on what I should check?

Perry Babin 15th November 2019 08:09 AM

It sounds like you either lost remote or the transistor failed. If the transistor failed, something it's supplying voltage to may be damaged.

Chopperbuilder 15th November 2019 08:34 PM

1 Attachment(s)
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.

Perry Babin 15th November 2019 09:04 PM

If you have no voltage reaching the IC and the transistor that you found supplies that voltage and the transistor isn't defective, it would appear that you have a broken connection.

Suspect any traces that run under capacitors.

Chopperbuilder 15th November 2019 09:27 PM

I found the problem. My meter wasn't getting an adequate ground.

I have 10.7v on pins 13 and 15.
Still have the problem in the audio section.


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