PG MS-275

[crazycody1993]

I have a phoenix gold MS-275 that one day while driving home from a truck show, quit playing. After trying to quickly diagnose the issue while driving, i decided to turn the stereo off and worry about it when i got home.

Once i got home i did what i could to dry and determine the issue. The only thing i could get to happen was with lot's of boost, the subwoofer would make a very quiet buzzing noise to follow the music. I pulled the amp out, and couldn't see anything burnt or missing. All i found was one of the nuts that mounts the speaker terminals had fallen off. I'm afraid one of the connections on the boars was short circuited. Has anyone else had this issue? or something similar to help me get this amp back on the road?

Any information would be greatly appreciated

 

[evianamp2011]

Woah, those nuts should not come loose, they have a tooth/lock washer. It may have damaged something by shorting it with the loose nut. The ic are likely to get shorted since all the pins/legs are so close, but this could happen pretty much with any component.


If it has original capacitors, then the dc filter caps should be replaced immediately. Those leak, so don't be surprised on what you see once you remove them. The electrolytic damages traces and via holes, that could also be past of the problem.

Check all the fets, rectifiers, outputs, pre drivers.

Perry will help you, or justoneamp. They know way more than i do.

 

[evianamp2011]

Double post.

 

[1moreamp]

Check the two 10 amp fuses near the power supply. If those are OK then start ohming out all the green and grey bodied fuse resistors located in each channels discrete amp section. Those are the likley suspects based on your detailed description.
You may have blown some transistors also, but for sure the fuses and the fuse resistors should be checked if the short happened like you described. This amp has VI current limiting built in to protect it in most cases from over current draw situations but dead shorts are fairly extreme and this protection may not have been able to react quickly enough.

This should start you for now. Let us know what you find...

 

[crazycody1993]

Woah, those nuts should not come loose, they have a tooth/lock washer. It may have damaged something by shorting it with the loose nut. The ic are likely to get shorted since all the pins/legs are so close, but this could happen pretty much with any component.


If it has original capacitors, then the dc filter caps should be replaced immediately. Those leak, so don't be surprised on what you see once you remove them. The electrolytic damages traces and via holes, that could also be past of the problem.

Check all the fets, rectifiers, outputs, pre drivers.

Perry will help you, or justoneamp. They know way more than i do.

I know they shouldnt be off, what i found was the output plug had been broken, so you basically had one nut holding a square piece of plastic, and the other nut holding all of the output wires.

1moreamp, I'll get the amp apart this week, I'll make sure and get you guys pictures so you can help me make sure I'm investigating the right areas.

I really really appreciate the input!