View Full Version : IBM 5150 won't start up

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.


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?

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?

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...

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.

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

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?

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

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.

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

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

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)].

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.

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