help on old computer (won't boot)

We have a neighbor who has an old e-machines 'puter. 500Mhz, 32 megs of ram, modem and CD.
Anyway she went to turn it on the other day and when she hit the switch for the power strip she told me she heard a buzzt and now the machine is completly dead.
Thinking it might be a power supply I asked her to bring it over. I cleaned out major amounts of dust, and cannot get any reponse to the power switch, no on light, no burr whiz or click. I have inspected the face of the circuit board, and can see no evidence of frying. I took the top off the power supply and again can see no frying.
Speaking to a friend that does tech support she told me she was leaning toward a DOA motherboard. Which I can understand, if the board is dead I can see the power supply not being turned on.
I was goning to swap the power supply with one from one of the several old cases I have here, but the mother board connectors are different. This e-machine has a double row connector with 20 pins (2 rows of 10), all my power supplies use two single row connectors. Damn.
I know the best solution would be a new puter, but this lady is out of work and cannot afford it. If I could fix this bad boy for $30-40 I would do it out of my pocket just because she is a good neighbor.

So can anyone narrow this one down for me? Suggest tests to determine if it is a MB or power supply? I do have a full assortment of tools including a DVOM. Also if it turns out to be the power supply where can I find one with a double row 20 pin connector?

The one Emachine I worked on had an ATX type power supply which is pretty standard. I was able to find a generic replacement for my brother’s box and it worked fine. I’m suprised you haven’t seen one before as the style with two plugs you are familiar with is pretty much obsolete.

If there’s no fan and no drive lights coming on, chances are its the PS that’s bad, not the mainboard. To test it, pull the power connector off the mainboard, but leave the drives connected (switching supplies need a minimum load to start properly). Jump the POWER_GOOD good wire to a ground wire using a short piece of bent paper clip. These will be found with this pinout. Then jump the POWER_ON to ground. If the PS fan and the drives power up, you’ll know the mainboard is bad.

That is what I thought at first. My friend who does do this for a living brought up the possible dead MB.

Q.E.D. I do have one guestion. After reading the article I don’t understand why I would jump the power_good to ground. I can see jumping the power_on to ground to kickstart the power supply, but I don’t understand why to jumper the power_good to ground.

Oh and Padeye my old cases are truely old, 486 vintage.

When the power supply fires up, the mainboard checks that the voltages and currents are within normal parameters, and if not, it opens the POWER_GOOD line which shuts off the supply to prevent damage to the board… If POWER_GOOD isn’t connected to ground, the PS won’t start.


Now I understand. Thank you for the assist. After dinner I will dig in and see what I can find.

Turned out as you and I expected Q.E.D. Power supply was dead. A quick trip to Fry’s Electronics to get a mini ATX power supply to fit in this small case and all is well.
$25.00 and my neighbor is a very happy camper.
Thank you for the info, and the very cool web link.