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  1. #1
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    Any ideas about this 400V, 1A Bench PSU?

    Hello,
    Does anyone have a schematic for this HSPY-400-01 Bench power supply? (400V, 1A)

    https://www.aliexpress.com/item/3259...d3c64182897-10

    Disassembled pics attached.
    I have now been banned from tinkering further with it.

    Ours blew up, and I took a look inside today, and indeed, it was the two switching FETs that had gone totally short from gate to drain to source. I took them out and was told to order new ones and then I was moved off this job. This is a shame as I was going to analyse this SMPS more.....may I ask if others have info on this power supply?, or any ideas, since I have been banned from further tinkering.
    This PSU worked until two weeks ago, and I have never powered anything with it at more than 12 Watts

    This PSU contains a top board which has a linear regulator output stage on it. A bottom board which has the offline isolated SMPS on it. Also a front board (which I haven’t unscrewed yet) and presumably this contains the microprocessors etc. There is also a little Fan PSU board. (This HSPY-400-01 PSU must have given its assemblers a few nervous breakdowns. I had to take 30 dis-assembly photographs.)

    The offline SMPS bit seems unusual for a 400V, 1A PSU..... It has no PFC stage. Instead there is the AC filter, and then the rectifier bridge…then a 330uF, 400v electrolytic capacitor. Then there is the transformer isolated SMPS. This appears to be a half bridge LLC converter (but possibly a series resonant converter of course) . It does comprise a current transformer. It does appear to have rail splitting film capacitors (each 200nF) which are supposed to protect LLC converters from startup transient damage etc. The Resonant capacitor appears to be 1 inch long 6.8nF film capacitor.
    The 68uF electrolytic output capacitor of the LLC converter is only 400V rated…and 400V is a bit tight for a 400v output PSU…the unit has a linear regulator output stage, so presumably the LLC SMPS is outputting a little more than 400V when the unit is outputting 400V.

    The LLC converter ( I believe it is that, after my short allotted time with it) looks very sparse on componentry. (pic attached) I cannot see a controller chip for it…….other than a IR21531S chip on a little daughter board which is a “self oscillating half bridge driver”...

    IR21531S datasheet
    https://www.infineon.com/dgdl/Infine...5355c8d26316b3

    This is a cause for some concern, since LLC converters have failure modes which really need either a custom microcontroller solution, or a custom LLC converter IC.
    Please may I ask if anyone has a schematic for this PSU?. I believe its very common as its so cheap. I am beginning to suspect that its not very robust at all.
    Can anyone confirm the topology?
    Last edited by treez; 15th October 2019 at 20:57.

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  2. #2
    Advanced Member level 5
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    Re: Any ideas about this 400V, 1A Bench PSU?

    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 it 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.



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