installed an ATX p.supply into what was a "miniATX" tower case - all done, but won't spin up :-(

I'm in the final phase of retrofitting an old ATX power supply (powertech "200 watt max" model kw-6200dl3n1) into an emachines that originally used a "micro ATX" power supply (illsan model isp 120si, "120 watt max"). all the sheet metal work and physical fitment is already done, all the connectors are plugged in correctly, but the ATX p. supply won't boot - its fan (and the CPU fan, and drives) don't spin up and the case front LED's don't light. in other words, "acts like a brick". I've tried different power cords in a 'known working' outlet - same deal. all wires connected, none 'unaccounted for'.

could this be the 'snag': the (newly installed) powertech ATX has a tiny connector coming out of it (which has three pin positions and two wires: black, purple, no wire) that the 'old' micro ATX ps lacks. what's the function of that connector? presently it's just hanging in there not connected to anything, so, can I just "jumper across it" to achieve 'power up' perhaps? or does it need to 'sense something'? it's approx (or possibly exactly) the same size as a cd-rom connector...this tiny connector comes 'directly out of' the power supply itself - it's not 'hanging off of' a drives power or any other connector. could it be just a fan connector? -big mystery to me-

according to sparkle's site, an ATX p.supply has a "negative 5v" function the miniATX p.supply lacks...and, UH-oh, a closer look reveals a few power supply to mobo main 20pin connector pinout -differences-

below, the 'old' illsan 120 watt connector (mobo connector pin numbers). both p.supplies the same unless noted:

1. orange
2. orange
3. black
4. red
5. black
6. red
7. black
8. grey (white wire on the powertech @ pin 8)
9. purple
10. yellow
11. orange
12. blue (brown wire on the powertech @ pin 12)
13. black
14. green
15. black
16. black
17. black
18. nothing, =no= wire (blue wire on the powertech ATX @ pin 18)
19. red
20. red

so, can I just clip a wire or two to 'remove' the 'negative 5v' function (and would that be enough to keep it from powering up, thru the front pushbutton?) which one, or 'ones' can I do without? or is that tiny 'unknown connector' the culprit? or maybe that tiny ATX mystery connector has a 'power up' function of some sort? maybe it's needs to be 'momentarily jumped' to power up the supply? -I got no clue-

I've tried numerous power cords, and numerous searches for more in-depth info (and/or schematics) on both of these power supplies, or what this tiny connector might in fact be on ANY makers power supply, to no avail. all comment appreciated, except those advising "buy another (or bigger) miniATX p.supply".

as a last resort, does anybody know where I might find 'labeled pinouts' for what the mobo connector functions ARE on ATX and 'miniATX' p.supplies? I did find some guys site with a schematic for a 200w ATX, but it did -not- include the 'mystery unknown connector' on mine...

I'd like to boot this thing...thanks in advance for tips, clues, and educating me,

tool

Do some reading.

thanks, travis, I've been reading and saw that page yesterday AM. admittedly, it DOES have good info re the ATX PS mobo connector pinouts (and I tried accessing a dead link on the page for more info, too). but that page:

1. makes no mention of the 'mystery connector' on my "microATX" PS, and
2. gives no schematic (or other info) regarding what the pinouts are on an "micro ATX" power supply to mobo connector (needed for comparison)

so, I guess I'm about a third of the way closer now to 'solving the great mystery'

thanks again

tool

ps-still haven't been able to locate pinouts for the mobo connector on an "ATX micro" power supply, as either a 'suggested industry standard'

-or- a schematic (or other specifics, in any form) for -any- makers mATX power supply...

:-\

I remember once I plugged a microATX power supply into a standard ATX motherboard and the PSU started billowing smoke. I would have thought the connector pinouts would be the same given that the connectors are identical and they're both flavors of ATX but apparently not.