Thread: Possible EPIA-M & Sproggy Solution

Hi All,

I have been reading all I can on the EPIA-M and Sproggy failing to allow the board to POST issue, after some research I may have found a trivial solution (I dont have an EPIA, but I do have a Maxim based PSU).

We basically know the more power, sproggy v2.8 ps_on and 5v standby add-ons have not fixed the problem. Also some people have observed that PWR_GOOD is not needed either. It seems like the PS_ON is the culprit, but I dont think it is a timing issue.

Someone measured that PS_ON goes to GND and then open... this got my brain ticking!

My ATX PSU requirements state (stripped version):
"when PS_ON is held high by PC or left open power supply should be off, when PS_ON goes to GND power supply should turn on"
That all makes sense... but then it states:
"this signal (PS_ON) should be held at +5VDC by a pullup resistor internal to the power supply"

BINGO... I pulled apart an old PSU, which has a 560 Ohm pullup resistor between the PS_ON (Gray) lead and standard +5VDC (Red) leads, a quick look at the Sproggy design and there is no pullup resistor.

I think the EPIA pulls PS_ON low, the PSU starts up, it then releases PS_ON and reads its value, which on an normal psu is 5v (via pullup resistor) but on a sproggy is a open circuit. The EPIA senses the open circuit and aborts POST assuming the PSU has failed.

So if someone with a EPIA-M and Sproggy would like to try this out and report back I would greatly appreciate it! I so want a M10000

Solution: Place a 560Ohm resistor between PS_ON (PIN14) and +5VDC (PIN4/6/19/20).

Someone with an OPUS may like to take a look and see if this is the case also.

NOTE: This is just a theory!

Thanks