Bastard power supply from hell!!!
I have a few motherboards floating around at any time.
They are useful if I need to make up a cheap second hand PC for a customer. I also happen to have 3 identical motherboards(d865glc), that are also the same as my main system… OK, a pentium 4 system is getting a bit old by todays standards, but it works well for me.
A while ago, I used a d86glc to make a second PC at home.
It worked well for a few months, then I needed to mothball it for a few months.
A few days ago, I needed it again, so I started it up again (it started OK), and left it running updates while I went out for a few hours.
When I came back, the PC was off.
Thats strange.
Anyway, hit the power button, and the lights come on for a few seconds, then go out.
OK, maybe the power supply has had it, so I plug in another PSU, only to see the same symptom: PC starts for a few seconds, then stops.
OK then, the motherboard has died. So I dig up one of my 2 spare (identical) motherboards, and being paranoid, I first connect it to the new power supply thats currently on the bench… It starts OK.
Good, now I swap motherboards, and connect everything up again, start the PC, go to the bios and check the settings.
I’m almost finished adjusting the settings, when the PC suddenly stops… all power is lost.
Hmmm, can I have a faulty motherboard and power supply? Highly unlikely.
Maybe the RAM? I pull out all the RAM, unplug all drives, etc, switch on, and the PC beeps (its saying it wants RAM)… OK, I plugin only 1 stick or RAM, but the PC won’t start.
I swap RAM sticks, and this time the PC starts… aHa, maybe it was just faulty RAM causing startup problems.
OK, back to the bios again… and again, I lose power before I can save any BIOS settings.
Whats going on?
The original motherboard won’t work with the new PSU, so I’m sure the motherboard is stuffed.
But why would the “newer” motherboard also fail?
I try swapping and reseating everything (including CPU), but nothing seems to work.
I sleep on it, and the next day, I decide to try the third motherboard on the bench with the new PSU… it works.
I plug the RAM into a test PC, and do a memtest… the RAM has no faults.
OK, I now plug the 3rd motherboard into the first PSU (thats still in the case). Nothing happens…
Hold on! As my fingers brush past some mobo capacitors, I sense some heat.
Capacitors shouldn’t heat up like that.
I cut all power to the PC, and check the mobo… the wires that go to the 12V, 4-pin plug on the mobo are also quite warm… a lot of components in that area are warm… why?
I decide to test the first PSU… I rig up my multimeter, and I expect to see the typical 5V and 12V, but instead I see values shifting between 100 and 230 Volts !
Maybe I’m having a bad dream… I plug the multimeter into the new PSU, and the voltages are normal… back to the original PSU: more high voltages.
My heart sinks: The semi-faulty power supply just fried 3 motherboards in less than a day.
Damn you, bastard power supply from hell!!!
This is one of those hindsight is 20/20 comments, but I would have broken the multimeter out sooner,lol. But that’s life.
Sorry to hear that, I’d probably make a post on how extremely pissed off I’d be if this would have happened to me. I guess no warranty for the mobos?
Ouch, that sucks!
Feel sorry for 3 of your lost motherboard. Because for that faulty PSU , you already lost them. That sound really sad, because even it is an old motherboard, that 3 can earn some money there if they are not fried. Really really feel sorry for you.
oh, ouch!
that is just the sort of thing that has contributed to my not fixing other people’s computers any more…. way too much aggravation!
It also happens to me and it is really a hassle especially if you have to work. I hope you fix it already.
Damn that would have to suck so much. I would have walked away from it swingin fists.
Your story of the Bastard PS from hell struck a cord
Some years ago, I had a non functioning PC brought to me
It didn’t take long to find that EVERYTHING except the Monitor (a CRT type) was fried. Even the KB and Mouse
I did some checks and found the PS was producing almost 300 volts
I made a minimal charge and told the client nothing was salvageable and to buy a new one
However it promoted me to do a bit of research
While there are 100’s of P/S designs they seems to fall into 2 main types (and some sub branches)
The cheaper ones used to turn the mains into DC, feed it directly into the pass transistor and some additional circuitry switchs the transistor off and on to regulate the output. If it failed, the full rectified mains voltage appeared on the output and screwed everything.
I really hope no more of these are produced
With type 2 the same happens, but the output of the transistor was fed into a transformer and from there additional regulators produced the different voltages. Most of these use an optical isolator to isolate the control signal from the output where it was fed back to control the switching of the pass transistor
With these there is total isolation between the High voltage input and the Low voltage output and only a failure of the Transformer could damage the computer components (very unlikely)
I think yours had to be a varient of Type 1. The designers of these need castration LOL