Focus FX-7000D HELP PLS!!

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Hi everyone!

I have this darn amp blowing those IRS21844S (half bridge driver IC)..amp was used to drive subs ´break-in´ and blowed couple of ampFETs (IRFP360LC).

I changed all those 360LC:s and IRS21844S and their diodes from driver board but NO! Everytime I install new IRS the amp will keep up about 30sec and then go to protect and blowes those IRS:s. I don´t know what to do with it..everything seems fine but it´s not, and customer is calling all the time ´is it already, is it already´ 😀

Amp ´works´ fine with driver board NOT installed, RAIL voltages OK, +/-5/12/15 voltages OK.......gate and pulldown resistors OK....what else?

Please help me with this issue, I´m all lost with this one!

E: A little update: Last effort to change those IRS:s did end up blowing couple ampFET´s also - again. I´m getting a bit frustrated with this one, now I have to change all 360LC:s again and IRS and diodes and......a 100$ peace again. And still haven´t find a reason for all this.

I have a 15Amp fuse in 12V supply line...even that didn´t blow -> the protection circuit was faster but even though those IRS blew!

This kind of output driver board:
20131010_181122.jpg
 
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Thank you for your answers guys!

I´ll order new parts today, so this takes a couple days until I get to test it again. But this time I´ll change also every U and Q on that driver board 😀

Could you tell me if those U3/U4/U6 are just normal op-amps like TL072 for example? Never had to change those and they are sanded.
 
Thank you for your answers guys!

I´ll order new parts today, so this takes a couple days until I get to test it again. But this time I´ll change also every U and Q on that driver board 😀

Could you tell me if those U3/U4/U6 are just normal op-amps like TL072 for example? Never had to change those and they are sanded.

U3- TL072 is integrator, U4- LM211 is voltage comparator, U6-LM393 for protection.

You can check every input and output of this ICs with the corresponding function. thats is pretty straight forward.
 
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U3- TL072 is integrator, U4- LM211 is voltage comparator, U6-LM393 for protection.

You can check every input and output of this ICs with the corresponding function. thats is pretty straight forward.


Yeah..thank you nonprof!

Just a bit scared that even with these replaces this damn thing won´t work....just a hunch 😀 But maybe I´ll manage, sometimes they just take a little more effort like one Carpower power 1/1000D - still having nightmares about that one 😀
 
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