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Old 06-18-2020, 08:12 PM   #24
pc7fan
Badcaps Veteran
 
Join Date: Aug 2013
City & State: Maritimes
My Country: Canada
Line Voltage: 250V Split-phased, 60 Hz
I'm a: Hobbyist Tech
Posts: 49
Default Re: QW-MS3010D 30V 10A Variable PSU Blown MOSFET

Yes, it is. Yes, you can put them in series. However unground the outputs.

Another common problem with these power supplies is the P75NF75 linear regulator FET fails D-S. (makes the supply lose regulation and mashes the output at 100% power)

These supplies are alright after you know their quirks...

The way you can cause that FET to fail is...

1. When you short the output when you set the voltage too high, hence dumping the supply's cap into the linear regulator FET, shorting drain-source.

2. Disconnect the load (esp. if an inductive load) while the supply is on. This scenario can cause inductive spiking, can cause the FET to short.

When this happens, the supply popped the output caps once on me. Mine had 2x 63V 330u caps, those vented, installed 1x 330u 100V and 2x 150u 100V. All Rubycon ZLHs. And I've got a few spare FETs.

Try to not do the two scenarios and your supply should do you well.

Last edited by pc7fan; 06-18-2020 at 08:14 PM..
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