Need service manual or schematics of behringer PMH1000 mixer

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I need service manual for a broken ( switching amplifier section and power supply...) PMH1000 powered mixer...Yeah I know it's only a Behringer, but I whant to fix it for a friend...First of all, booth power mosfet and drivers have blow in the power stage (dead short) and this may have blow PFC stage in the power supply. Only the section with TopSwitch work, no power output.

At least, if nobody have it, I will just do an un-powered mixer with it....

Thanks

fredos
 
Thank you very much oldmaelstrom2 for this nice pdf.

If they got the current limiting feature of the PFC to work properly, it should survive dead shorts on the outputs without problem.

SHAME on the way current limiting is implemented in the class D amplifiers, though.
 
Repaired!

No Eva, I dont think they have done a great job on the protection schem...Power supply blow after dead short on amplifier mosfet...

So the HCA4001 seem to work well. The sound of this crap is like all berhinger crap...Bad! But power amp seem efficient, duty cycle is limited into the HCA4001, so no need to find a way to keep gate charged...Power supply provide +/- 56V, very well regulated..

Some ugly 60Hz noise inside transformer, specialy with 200 watts load and more, but still regulated. Began to drop over 460 watts until 0V with a PAR 64 1000 watts lamp. Did'nt try short, I dont whant to blow it again!

Thanks for serviec manual!

Fredos
 
In my PFC designs I got smooth zero crossing by allowing up to 100% duty cycle and by optimizing frequency compensation of the average current control loop. A too *high* PFC inductor value can also produce this behaviour but only for heavy loads. In a finished product the noise is not that easy to fix.
 
100% duty cycle in the PFC allows the boost inductor to be left connected to the input rectified mains voltage 100% of the time when instantaneous input voltage is very small. This is required for good zero-cross performance because the required duty cycle approaches 100% near zero cross as the input voltage becomes only a few volts. When duty cycle is limited, the current loop just can't follow the voltage waveform when voltage approaches 0.

Control ICs like L4981A impose a dumb 90% limit (that I skip with a tweak in my designs). I don't know how other ICs behave as datasheets usually tell little about this.
 
PMH1000

I noticed in the first post of this thread you had blown Power MosFETs and drivers. That's exactly what is wrong with this one. Did you have to replace the HCA4001 or was yours ok? I can find the other components easily just having problems finding the IC. Thanks.
 
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