Hi, I've stripped a working PSU, (its spare and old), of its heat-sinks. As far as I can tell, my wiring is okay. I've extended the connections to all the mounted semiconductors and mounted on a huge heat-sink, and just in case the heat-sinks carried a connection from one side of the board to the other, I soldered a bridge wire in where the heat-sink mounting tabs were. I connected a cdrom drive and an old motherboard and plugged it in. Nothing! The CPU fan turns a little then stops. My DMM measured 3 volts on the 12 volt rail then 0 volts.
Does anyone know whats up with this?
Fuzzymuff🙂
Does anyone know whats up with this?
Fuzzymuff🙂
Hi Fuzzymuff
OK, I'll take a stab at this (since no-one else is).
Don't know too much about SMPS but:
1) The semiconductors you've put on the big heatsink probably need to be insulated from it (with mica washers or similar) otherwise those with metal cases or tabs will all be short-circuited through the heatsink.
2) SMPS normally use high-speed switching, so maybe it just can't work with long leads to the switching transistors due to wiring inductance etc.
Good luck - Godfrey
OK, I'll take a stab at this (since no-one else is).
Don't know too much about SMPS but:
1) The semiconductors you've put on the big heatsink probably need to be insulated from it (with mica washers or similar) otherwise those with metal cases or tabs will all be short-circuited through the heatsink.
2) SMPS normally use high-speed switching, so maybe it just can't work with long leads to the switching transistors due to wiring inductance etc.
Good luck - Godfrey
- Status
- Not open for further replies.