Products > Test Equipment
HSPY-400-01 Bench PSU blows fuse every time switched ON.
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thinkfat:

--- Quote from: treez on October 16, 2019, 11:02:17 am ---Also, i couldnt see any feedback  for the LLC stage...no opto or anything comming back across the isolation  barrier

--- End quote ---

Primary-side feedback winding on the transformer?
CDaniel:
This kind of controllers don't use feedback , the outputs are at 50% duty cycle and can't be changed . You can consider them as a transformer + rectifier+ filter cap . No regulation .

In theory for resonant converters it is possible to use feedback to modify the running frequency and achieve regulation , but this is too "fancy" for what we have here .
ocset:
I replaced the shorted LLC converter FETs in the 400V PSU...and the IR21531S, but when i re-assembled and switched on it went bang again and wouldnt work.
Once again, the FETs blew up and were again short G_D_S
The fan works, and the LCD display, but they come off the pilot power supply  which is near  the fan.
Coming to think of it, its probably a fault with something on the output PCB.....something on there is probably short circuit........also, High voltage FETs blowing up is probably not going to do the little control & Drive PCB too much good either.

So if i was  precscribed to do further work on this PSU, then i would look to again replace the FETs and control chip. and then try and run the main LLC SMPS on its own (without being connected  to the output PCB)............if OK, i would see if their were shorts on the Output PCB.

Any further FMEA on this much appreciated as i have not been allowed more time to tinker.
CDaniel:
Every semiconductor should be checked for obvious shorts . Especialy those diodes and SMD transistors in the grids of power transistors that are visible in pictures . An 100W light bulb in place of the fuse could save the power transistors until all issues are solved .
ocset:
thanks, ill see if i can get more time.
I doubt it, theyll probably just buy a new one for £100.....or less if we buy direct from China.
There does not appear to be a  manual, so i dont know if it has short circuit output protection.
I suspect someone has shorted it and the output board is blown.
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