Funny to find this thread today when needed. Just Joined All About Circuits.today (RCAROBERT)
I was trying to charge a a 14 volt Lithium ion for my hedge trimmer. Reversed the wires and blew power supply QW-MS305D.
Output Plus and Minus shorted together
.Any one with a schematic Need schematic can not read components to replace .. IRF840 Mosfet and TL's will get replaced when I can find my stash.
Any and all help appreciated.I learned some tricks that work.. "Use a different source and connect to blown supply output terminals. Shorted DEVICES If you have a IR camera or Gunit will flag "HOT" spot. tHANKS

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I am a newbee. Old post Power supply qw-ms305d old thread lots of info on this problem. Charged many batteries with this psu. Constant current mode. Fyi ,, charging 14 volt battery pack. (backwards)) blew 2 sm diodes es2g's , removed shorted diodes, added a uf5408g across output terminals and made a dual adapter plug with 2 diodes .. Bananna plugs to make it failsafe . Negative gets cathode to output ,positive plug gets anode to plug. Output of power supply has to be compensated for diode forward voltage. Thanks for all the pictures and work involved..Rcarobert

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I think we really do need a picture (a schematic) if we are to be of any help.

 

You can find more information and a circuit diagram here:

https://forum.allaboutcircuits.com/threads/qw-ms305d-30v-5a-bench-psu-repair.180638/