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mac512
September 21st, 2013, 10:32 AM
Hi there!

i finally made the transplant from an ATX PSU to my 5150 PSU. I know it works as i tested it with an 286 motherboard (i thought it was dead but it worked just fine :D).

Unfortunately when i connected the "new" PSU to my 5150 motherboard ... nothing happened! Not a single beep or video. It didn't made the classic light "clack" (i don't know how to describe it but i think its a small switch that works only at the begining of the startup sequence) when the PC starts.

I thought the motherboard was dead and connected a second one i have for spares but nothing happened again.

I keep scratching the head but can't figure out what's happening. Any ideas?

Thank you.

Mac512.

Stone
September 21st, 2013, 10:46 AM
Have you tried it with no cards in the 5150 slots? A card with a short can cause this.

Have you got a meter to see if the PSU is putting out juice when connected to the 5150?

If you have a hard drive connected to the power of the PSU does it spin?

BuggZ
September 21st, 2013, 10:59 AM
IIRC the 5150 does not have a connection on Pin 2 of P8 but an AT power supply like those used in 286 systems have +5v on that pin. Check the power supply connectors to make sure you have the 2 ground pins on P8 next to the 2 ground pins on P9 when connected to the motherboard (the 4 ground wires should be in the middle). Was the 5150 working before the power supply transplant?

mac512
September 21st, 2013, 11:47 AM
what i've done so far:

-tried with P8-Pin2 on and off (+5V)
-tried with a HD connected (spins OK)
-tried with a 286 motherboard and tested OK for the VGA card and the floppy card (got floppy activity in both 3.5 and 5.25 drives)
-tried 2 5150 motherboards: one is known to be good and the other got 220V instead of 110V.

Still no go...

mac512
September 21st, 2013, 11:50 AM
I forgot to tell you that i have a third card plugged in. It's a SixPack Plus fully populated with 384Kb.

Stone
September 21st, 2013, 12:33 PM
Are you sure that pin #1, power good, is properly connected to the ATX PSU?

mac512
September 21st, 2013, 02:12 PM
I really don't know. I connected pin #1 to +5V. Is there a special signal in the ATX PSU for power good?

Stone
September 21st, 2013, 02:23 PM
I don't know if it has one but if it keeps running then it's ok.

mac512
September 21st, 2013, 02:57 PM
Well, it supplied enough power for the 286 motherboard to run with VGA and a floppy cards, so i guess it's OK.

Stone
September 21st, 2013, 03:20 PM
But does it keep running when the 5150 is on it?

modem7
September 21st, 2013, 04:10 PM
Try the 5150 diagnostic procedure [here (http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm)].

modem7
September 21st, 2013, 04:14 PM
Is there a special signal in the ATX PSU for power good?
Yes, the PWR_OK signal shown [here (http://pinouts.ru/Power/atxpower_pinout.shtml)].

mac512
September 22nd, 2013, 12:08 PM
OK. Replaced the +5V cable that i've connected to the power good (pin 1 on P8 connector) with the PWR_OK. Did the diagnostic recommended and ... IT WORKS!!!

Thank you all guys. You've been really kind to help me get my computer back to working order.

mac512
September 23rd, 2013, 02:08 AM
I'm so happy that i want to share this pictures!

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