Need help with amp repair!

I have a 16-st1500 Memphis class d. I got it used in the trade not working Took it apart and found out some of the FETs for the power suppy were Smoked. Order new ones same part as befor. Replaced alll of them and the 494 chip the power suppy controller. After all that when you power it up the relay clicks over and powers up all good for about 5 to 10 secs then makes this squealing noise and starts pulling alot of amps so i turn it off. i need a few pointers have not ran into this issue before. Also for test purposes I have a Memphis 16-st1600 in working order that ive been using for specs and info. If you need anymore info just let me know.

Thanks shawn
 
Thanks everyone for your input hear are some pics of the amp. And i though i had found the cause of the issue but i gess not.
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irribeo

Member
2013-04-01 2:46 pm
Connect a load or speaker. Always test classD with load. Unless you have manual explicitely stating it is allowed to be powered without load (means it has some protection, with open output classD output normally will start to oscillate, parts can get real hot, could even squeal I guess)
 
And i have no load on it or rca. Just hooked up the power on my test bench. 20 amp Power supply continuous @ 13.8 volts

Class d can do odd things with no load.
The 2092 based class d amps can have the output sit at +17V.

If the amp does oscillate then with no load to damp the output filter the output filter choke will ring at very high volts and possible blow output filter capacitor and/or other components.