# Schematics Dual XPR 522



## rfitts46 (6 mo ago)

I have been repairing home/professional audio equipment for 15 years as a hobby. I have learned the power of schematics. Just wondering for those that repair mobile audio equipment how does one start to diagnosis without a schematic? Are there any universal schematics since alot of mobile power amps are similar. I purchased a new used Dual XPR522 and it has operated well for months. Now there is an intermittent static noise on the right channel. Removed amp and put it on the bench and powered it up with speakers and confirmed it is the amp. Monitored DC offset on right channel and at power up 15mV after several minutes it increases to 150/200mV. Took it out of the aluminum shell and have it bare board on the bench. Nothing smoked or discolored. Wanted to inspect solder connections and traces......suspicious of a bad solder joint.
Being one channel it is not power supply related. Most likely something in the amplifier stages.
The intermittent static noise is not affected by volume.
and I already know that this amp is probably considered a throw away but I am one of those individuals that cant bring themselves to throw away a piece of electrical equipment that possibly just has a bad solder connection.


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## bnae38 (Oct 3, 2015)

Not much trump's experience imo, takes some time to learn.

Start here, bcae1.com. Great info there.

There are some schematics out there, usually not the ones you need lol.

Clarion schematics are useably close to arc audio though. Plenty of jbl schematics out there too.

Pots and switches cause one hell of a lot of issues in mobile audio amps fwiw. I don't think that's the issue in yours unfortunately if you're seeing dc offset... Power amp has to be ac coupled. Poor solder joints is a good place to start.


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## rfitts46 (6 mo ago)

bnae38, can you post or send to me the closest schematic that you have to the XPR522? Just to use as a reference. I see they use a 14 pin quad amp
j-fet chip for first stage. Amp is displaying intermittent static noise which is unaffected by volume control. On the bench observed the DC Offset increase when this occurs. 

There is what appears a TO-92 package size component that is on the heatsink....one on each channel. Do you know if that is bias or over temp protect?


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## bnae38 (Oct 3, 2015)

No idea without having it in front of me, I couldn't find any pcb shots on the net when I looked the other day.


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## rfitts46 (6 mo ago)

Image ofpcb


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