PSU Test

Hi guys,
I read somewhere that the psu can be turned on by joining one of the 2 pins in the 24 pin array block to test weather the PSU is working or not... Any ideas which 2 pins are these???
Cheers
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More about test
  1. Pins 14 and 15, which are green and black, respectively.
  2. erm on my hiper i repaired (just the fan, not the power circuit), 14=blue, 15=black and 16=green, which from the manual is: -12V, COM (0V /GND i'm thinking), and PS_ON#. Its 24-pin too.

    which would mean in this case, you short 15 & 16?

    i managed to get it to get in standby mode, but couldn't get it to power on. the fans just "blipped" and nothing else, there is another connection called PWR_ON, but i never got round to testing as i was only on my lunch break! :D

    i can't remember which pins i shorted( most likely PS_ON# and COM, but don't quote me) but i made sure, by reading the pin outs in the manual, and checking what voltage was on the pins with a multimeter , that i wasn't shorting a supply rail.
  3. You'll have to to draw some power from the PSU in order for it to stay powered on. Just connect a CD ROM drive and then it should work...


    Edit deleted
  4. ahh cheers, thought i might need to.
  5. Ok second input. It works. Just measured the rails and its powering on....
  6. It even works without any device attached...
  7. how'd you do that? which is it? with or without?
  8. You connect the green wire to any ground and keep it connected.. nothing attached. Then you could use a multimeter to measure all rails.
  9. got it, CD-ROM on output, fans power up, CD-ROM Ejects when pressed.

    good enough for me.

    found out that PS_ON# & COM shorted and PWR_ON & PS_ON# work both the same......found that COM to PWR_ON with a voltmeter is 0V....odd, perhaps more too it than that.
  10. wouse101 said:
    ......found that COM to PWR_ON with a voltmeter is 0V....odd, perhaps more too it than that.


    PWR_On is pulled up by default. You should read around 5V. If not then you've pinpointed the (or a) problem...
  11. hmm might have to double check that.

    if its pulled up, should it not be low anyway in order to be dragged to a higher voltage?
  12. No it's 5V high and it's going 0V once you connect it to gnd...

    (btw; last transmission tonight. I'm in europe and it's getting late... I'll check back in about 10 hrs on the thread, and I'll be ready to experiment a lot more tomorrow...)
  13. no rush mate
  14. Well I DID some experimenting today. I took my old PSU and converted it to a "lab" power supply. +5 -5 +12 -12 +3.3 and GND are now accessible via plugs. This gives a wide range of possible voltages. To turn it on I connected GND and the Green power_on wire to a switch. As power_OK indicator I use a LED connected to the grey Power_OK line (5V high), 220 resistor to GND. What I found out however is that most PSU's need a load to stay powered on. Usually a load on the 5V rail will be enough. For that purpose I use a 10 Ohm 17W resistor between 5V and GND. You should use (little bit of calculation) at least a 10W resistor. I mounted the resistor (which is pretty big) to the metal casing in front of the fan. IT doesn't get too hot like that. For a little gadget you could use the purple "standby" chord to indicate that you're turned off...

    HOWEVER: that is pretty dangerous tinkering. Before you open a PSU you should be aware that the capacities inside will most probably still be charged and they can provide a strong and dangerous shock. Furthermore I would suggest to use fuses at least on the GND. 1A at most. But it would be better to use fuses on all connections. A short without any fuse between random rails would be pretty "hot". Especially with high power PSU's.

    You see; our discussion yesterday has inspired me quite a bit:)
  15. good work.

    Bit of over kill with the 10OHM resistor. 17W is a lot when 10ohms on 5v is only putting out 2.5watts.

    but if thats all you had kicking around, then fair play.
  16. Well at least the resistor doesn't get hot...
  17. true, overkill never hurt anyone :D
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