I never came across this, but perhaps it's voltage regulator failed?

I have come across this before, and yes, it might be a fried voltage regulator. When the VR failed on my 486 board, I got the same symptoms: 5V CPUs would work fine, but it wouldn't boot with 3.3V CPUs.

If you know on which end to grab a soldering iron, this should be relatively easy to fix.

I had the same problem with a M919 while rebuilding my junker pc. I took the easy route and switched with another M919 I had lyting around

Alrighty, I tried the cyrix chip again and it turned on with 5 volts, it got to the windows 98 screen then bluescreened, I switched the computer off after that experiment with fear of frying the cpu.

The system would'nt work with 3 or 4 volts.

I don't know what a voltage regulator is but I may have found it or the problem, its located next to a small heatsink, its a cylinder green in colour with 4 lines acorss it coloured Yellow, Blue(or black), brown and silver, the cylinder is about 3mm wide and about 8mm long, it has a couple of blackish scorch marks top and bottom, does this sound like a voltage regulator? Its located about 20mm from the voltage jumpers, that heatsink is about 10mm x 10mm x5mm wide.

Can you get a photo of the thing you are describing? it sounds like something else.
This is what a voltage regulator usually looks like: http://www.societyofrobots.com/images/sbs_vol … e_regulator.JPG

dirkmirk wrote:

Alrighty, I tried the cyrix chip again and it turned on with 5 volts, it got to the windows 98 screen then bluescreened, I switched the computer off after that experiment with fear of frying the cpu.

The system would'nt work with 3 or 4 volts.

I don't know what a voltage regulator is but I may have found it or the problem, its located next to a small heatsink, its a cylinder green in colour with 4 lines acorss it coloured Yellow, Blue(or black), brown and silver, the cylinder is about 3mm wide and about 8mm long, it has a couple of blackish scorch marks top and bottom, does this sound like a voltage regulator? Its located about 20mm from the voltage jumpers, that heatsink is about 10mm x 10mm x5mm wide.

What you described sounds more like a capacitor. If it is bulging and has brown crusty stuff showing, then it has started to leak.
Check for pics in google images and search for "bulging capacitors" to see if that's what your problem is

That thing with the heatsink looks like the voltage regulator you linked excpet mine has a heatsink? You can see that green cylinder next to it that looks scorched, to the right is the voltage jumpers W1 & JP13, its set to 5V on W1, JP13 sets 3 & 4V

The burn marks look to be caused by the heatsink (you can tell by the fins). It's possible, though not sure, that green cylinder has something to do with your issues. Btw, it looks like a giant resistor or something

^ Yes, it appears to be a 2-3 watt-rated through-hole carbon resistor. If you're skeptical about it you can always use a multimeter to check and see if the value is consistent with the color bands (although it would work best if you desoldered it and measured it by itself - but in this case a ballpark estimate is reasonable enough as long as there's no power going through the board).

http://www.elexp.com/t_resist.htm

im going to be out of luck for any soldering, local repair shops charge $60 just to have look,hopefully the computer recycler can find me a 5x86 box.

# THE heatsink thing is the voltage regulator?

leileilol wrote:

I had the same problem with a M919 while rebuilding my junker pc. I took the easy route and switched with another M919 I had lyting around

Which is nice if you happen to have an identical, or at least functionally equivalent, motherboard lying around but some people may not have accumulated the massive piles of old computer parts that some of us here have. 😜

dirkmirk wrote:

im going to be out of luck for any soldering, local repair shops charge $60 just to have look,hopefully the computer recycler can find me a 5x86 box.

# THE heatsink thing is the voltage regulator?

Almost, the heatsink is attached to the voltage regulator (the black thingy with 2 or 3 metal legs soldered to the motherboard) 😉

Yep voltage regulators often have heatsinks attached. It shouldnt be hard to replace, look up some s
oldering guides on the web and have a go. I'd be willing to have a crack at it; if you're going to throw it out I'll buy it off you.