Active Load For PSU Repair Work

[Pete_kaye]

This is slightly OTT but .. when i look again at my PSU,I notice that 2 connectors are marked P8 and P9.They look identical but have completely different voltages from them(+coloured leads ).What prevents them being connected to the wrong devices?

[techiesteve]

PC PSU connectors prior to the ATX type had 2 x 6 pin connectors, P8 and P9. They were inserted so the black (common) wires were adjacent to each other.

[Pete_kaye]

Last night ,I connected acar radio to the 12 v line and it worked fine BUt I noticed that the voltage across from my PSU was 9.8V .I checked againsta new 9V battery and got 9.7v so DMM ok .Should I suspect the PSU? You might need to see my earlier posts.

You will need to load the 5V line to get the rest to work properly.

[neon indicator]

12V parking bulb on 5V line.

Yes, you don't need much, enough to stop a single 'pulse' from the switcher going over 5V. If you used a 6V (motorcycle) bulb you will have useful light too.

[Railmaster_UK]

For PC Computer power suppliers would not something like HDD FDD and mainboard give suitable loads . You could fit them in a couple of wooden boxes and run the inputs to a set of further connectors on a peice of board , and then plug into those connectors you required psu for testing. Only problem I can think of is if psu sends how too high voltage or current and kills the mainboard.

[techiesteve]

Personally I would always use an ally clad power resistor bonded to the case, as I have a large box of 10 -100W low values left over from previous projects. I use a white thermal bonding compound with a bottle of activator to fix.