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Old 4th January 2013, 02:39 PM   #3151
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Quote:
Originally Posted by andrewlebon View Post
SOME TESTING PICS on 1500watt load
warm regards
andrew lebon
hello sir... this is amp or smps ?
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Old 4th January 2013, 02:40 PM   #3152
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Max SOA for IRFP4227 is 30A at 70V(drain-source) for 100usec pulse duration.

5 ms is too long... protection should kick in at <= 100us, otherwise the mosfet might not survive.
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Old 4th January 2013, 03:11 PM   #3153
manojtm is offline manojtm  India
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Quote:
Max SOA for IRFP4227 is 30A at 70V(drain-source) for 100usec pulse duration.

5 ms is too long... protection should kick in at <= 100us, otherwise the mosfet might not survive.
Hi,Jlester,

OC protect sense should be below 100us so not a problem for MOSFET
i said DC protect sense is 10ms

Regards
MANOJ
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Old 5th January 2013, 03:28 AM   #3154
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Sorry, I misinterpreted your post.
Guess I have to integrate the lm311+ne555 OCP protect in the pcb.

Thanks!
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Old 5th January 2013, 04:41 AM   #3155
manojtm is offline manojtm  India
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Quote:
Guess I have to integrate the lm311+ne555 OCP protect in the pcb.
Hi Jlester

your class d fsw=250KHz (Period is 4us) so you need 25us sense is max for OC(high current) detect for IRFP4227.so only ne555 is enough for OC sense(15us).Lm311+ne555 is better choice for high freq. operation

Regards
Manoj
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Old 5th January 2013, 06:24 AM   #3156
akraj is offline akraj  Bangladesh
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Hi Manoj:

I managed to repaid both the boards, now the BIAS voltage is okay, it is +ve with reference to -Ve rail.

and Amp board has 6.2 volts at two side, output from 7806 is okay from -ve reference.

now the problem is the 47ohms resistors are burning out immediately when I power on, and I get some noise from main inductor (core from old PC psu).

and the relay of power board triggered one/two times but now it is not switching and connect spk connection.

There is 0.2mil volt at spk out, FETs are just warming.

Please suggest me what to check now and which position to stop 47ohms burn and make the amp workable.

Thanks in advance.

Last edited by akraj; 5th January 2013 at 06:26 AM.
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Old 5th January 2013, 10:05 AM   #3157
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FET's are ok or not did u chek them.?? and how about ir 2110 ???
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Old 5th January 2013, 10:34 AM   #3158
akraj is offline akraj  Bangladesh
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I checked FER's, they are okay. How to check IR2110? Or 7404?
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Old 5th January 2013, 01:10 PM   #3159
IRSound is offline IRSound  Germany
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Quote:
How to check IR2110? Or 7404?
check output pulses with scope. or replace them with new one if you know the problem come from this components.
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Old 5th January 2013, 04:08 PM   #3160
akraj is offline akraj  Bangladesh
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Quote:
Originally Posted by IRSound View Post
check output pulses with scope. or replace them with new one if you know the problem come from this components.
I replaced all the IC's couple of times but no luck. Need to check with scope but I don have that.

I can manage scope, I guess but what will be the idle data/output from ir or 7404 or op amps.

Now the output relay is not conducting. No dc/AC volt at output, guess this is usual but if I connect Spk directly, touching input pins of op-amps then it starts huge noise even after removing my finger! Around 14dc comes from Spk line. After off/on voltage is gone.

Where I'm making mistake?

Last edited by akraj; 5th January 2013 at 04:31 PM.
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