JLHD 750Watts - high rail voltage

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nonprof

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Joined 2011
Hello!

I want to restore this amp after a couple of years stuck. But I think my limitation had reached on this amp, the rail voltages is too high, it produces high AC voltage up to 110V. Putting back the rectifier diode the DC voltage reached up to 120VDC and this diode gets too hot...

I measured the PS switching freq around 49Khz. I have a perfect gate square wave into IRF3205s mosfets.

Please help...
 
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nonprof

Member
Joined 2011
JonSnell Electronic said:
If too high I expect the regulation has failed. The PSU will be either pulse width modulation or frequency regulated. In the latter, the frequency rises and the transformer gets less efficient so the voltage produced gets less.
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So do you mean I should get higher frequency to make the voltage lower? This amp is PWM or a frequency modulated? I've seen the McIntosh amp, it is PWM regulation.

I have schematic of this amp, could somebody tell me which part of the circuit detects the output voltage? or any sensor?
 
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