Used in a Canon printer to provide 24V supply.
Printer was dead and I could measure no voltage out of PS so I opened it up. Was presented with a main electrolytic which had electrolyte crystals coming from its base (and a leg which subsequently fell off), a blown 2A fuse, 2 power diodes short and the main switching FET was short.
Replaced all components and expected it to work. With no load I get ~8VDC which I assume to be correct for standby mode. However, plug in the printer and the main FET blows short circuit and takes out diodes and fuse. (I've since put an incandescent lamp in series with the input supply to limit short circuit current and replaced all components and repeated. Again it took out the main FET again once connected to the printer.)
I'm substituting the FET with a 13NM60N, which by my reading of the specs, should be a suitable substitute for the 2SK3567 used in the original circuit.
The schematic I've posted is not exactly the same as my circuit but close enough to understand how the circuit works.
Any suggestions much appreciated.
(By the way, if anyone is wondering why I'm bothering to repair this PS, the owner of the printer is very attached to it. Obviously she is very comfortable in how she drives her old printer from her computer. Furthermore, it came in via a"Remakery" we operate. A not-for-profit volunteer group trying to save electrical gear from ending up in landfill.)
Printer was dead and I could measure no voltage out of PS so I opened it up. Was presented with a main electrolytic which had electrolyte crystals coming from its base (and a leg which subsequently fell off), a blown 2A fuse, 2 power diodes short and the main switching FET was short.
Replaced all components and expected it to work. With no load I get ~8VDC which I assume to be correct for standby mode. However, plug in the printer and the main FET blows short circuit and takes out diodes and fuse. (I've since put an incandescent lamp in series with the input supply to limit short circuit current and replaced all components and repeated. Again it took out the main FET again once connected to the printer.)
I'm substituting the FET with a 13NM60N, which by my reading of the specs, should be a suitable substitute for the 2SK3567 used in the original circuit.
The schematic I've posted is not exactly the same as my circuit but close enough to understand how the circuit works.
Any suggestions much appreciated.
(By the way, if anyone is wondering why I'm bothering to repair this PS, the owner of the printer is very attached to it. Obviously she is very comfortable in how she drives her old printer from her computer. Furthermore, it came in via a"Remakery" we operate. A not-for-profit volunteer group trying to save electrical gear from ending up in landfill.)
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