Power Unit Question

[Rudi]

I have two questions concerning my PC's power unit:
Over the holidays my PC went on the blink. One morning I switched it on and nothing happened. The harddrive didn't start up, the CD rom's and the A:drive did not start up, and the monitor did not turn on! The only activity on he PC was the cooling fan at the back of the box and the CPU fan that was spinning!????
1. Is this a power unit blow-out??? (Initially I thought my harddrive crashed, but then I noticed nothing else powered up either!)
2. If I need to replace my power unit, (which is a 230 volt) unit, must i replace it with the same voltage, or can it be slightly higher or lower???

Thanx

[bigaldoc]

If you saw the CPU fan running, it sounds like you already have the cover off, huh? I've never heard of this happening, but have you checked the power supply's connector on the motherboard to see if it's seated tightly? It sure sounds like a "dead" PSU but I suppose it could be the mobo. It wouldn't hurt to (with power OFF, of course) check as many other connections for tightness as you can, including the CPU. At least if it is the PSU, it's one of the easier components to replace. I really don't know about your voltage question, since most, if not all, of the ones we see here in the USA have a little red switch for "our voltage" as opposed to the "higher voltage." I think many folks here even tend to refer to the two as 110 or 230 with no technical range distinction. One thing for sure, based on a number of Lounge threads, don't go "cheap-o" on a replacement. Get a good one. If you haven't already done it, search this board for some recommendations. Good luck!

[Rudi]

Thanx BigAl...
You are right...I had the cover off, and all was in place. It baffles me too what went wrong, as I heard no power unit blowout when I switched the PC on??!!
I'll do some more homework before I go out and purchase a new PSU...
<img src=/S/cheers.gif border=0 alt=cheers width=30 height=16>

[JohnGray]

Your question 2 seems to be based on a false premiss -- you will either get a 230 V PSU or a "universal" one, which will detect what is the mains voltage and frequency, and adjust accordingly.

Were you thinking you could get a 250 V PSU, or a 210 V one, perhaps? "Pas de chance", as they say in French!

John

[Lyra_J]

I know this is probably a silly question, but was it definitely volts you were talking about, and not watts Rudi?

[MarkJ]

Hi Rudi,

This has happened to me before as well. It's been a while, but I believe the culprit was a motherboard that had gone bad. The fact that the fans are spinning means that there is still some juice flowing.

Also, I believe Lyra is correct - you were referring to Watts, not volts. You can use a power supply of any wattage - the more, the better! <img src=/S/evilgrin.gif border=0 alt=evilgrin width=15 height=15>
On a side note, I recently upgraded from a very cheap 420 W to a very expensive 480 W. The difference in system stability is amazing! I was running within the upper limits of what my old power supply would handle (6 fans, 2 hard drives, 2 optical drives, etc), and the new one is meant to handle much more.

Check the motherboard and keep us posted!

[Rudi]

Sorry Lyra...my mind is still saturated with the En-Lightning-Ment thread in Scuttlebutt! There we talk about volts, not watts!!
<img src=/S/cheers.gif border=0 alt=cheers width=30 height=16>

[Rudi]

Thanks for your reply Mark. This never occured to me. I'll open the box again and check to see if I can see a light or something on the motherboard to indicate this!

Though your reply is informative...I hope it is the PSU...as this will be easier and cheaper to replace!
<img src=/S/cheers.gif border=0 alt=cheers width=30 height=16>

[Rudi]

<hr>Check the motherboard and keep us posted!<hr>

Just to update all who are interested!!!

Mark, you were correct in your diagnosis! The PSU was fine, although I did eventaully replace it with one that had a higher wattage! The culprit was indeed the motherboard. The technician mensioned something to the point that it short-circuited and burned out a track???

I am still amazed at the fact that this small problem had such VAST effects; the fact that my entire system was dead - monitor, ALL drives etc.

PS: I burried my motherboard in the backyard and purchased a new motherboard....and she is working fine again!!!

<img src=/S/cheers.gif border=0 alt=cheers width=30 height=16> and <img src=/S/thankyou.gif border=0 alt=thankyou width=40 height=15>

[Lyra_J]

Thanks for the update Rudi. Good to hear all's well with your 'puter now

<img src=/S/cheers.gif border=0 alt=cheers width=30 height=16>

[Leif]

>>The technician mensioned something to the point that it short-circuited and burned out a track???
I am still amazed at the fact that this small problem had such VAST effects; the fact that my entire system was dead - monitor, ALL drives etc.

Well, it depends on the 'it' that the technician mentioned. It could be he didn't know, and it may be not viable to find out . Any one of a number of components could have failed and created a short that would burn out a track. I would guess that it would be a power line that had gone, as generally there would not be enough current flowing in any data or address busses to do any damage, and with (say) your 5V rail gone, nothing is going to start up or get a signal to start up.

In other words, what you see as a small problem, is probably quite significant. If you liken it to the human body, a blood clot affecting the supply of fresh blood to your finger may only affect your finger, but a similar sized blood clot affecting the supply to the brain would have slightly more serious consequences. In a way you should be thankful you could actually see some damage; if a component had failed internally without any outward sign, you could find yourself in a limbo where, without spending time and/or money, you would never know the cause of the failure.

[viking33]

Rudi,

Leif has it right exactly.

When a PCs foil or track burns out, it is usually the effect and not the cause of the board failure. That is, a current overload somewhere such as a failed filter cap will cause the foil that is connected to the cap to actually burn up and cause an open circuit. ALMOST like a fuse blowing. Repairing the blown foil is easy to do but the original cause is still there. Most foil blowouts are in the power supply circuitry since they carry the most amount of current. ( amperage ) Signal circuits rarely burn out. Depending on how fast the open circuit occurs will usually determine if other components take a dive also.

[bill_bright]

I think a few things need to be mentioned here. ATX power supplies supply +12VDC, -12VDC, +5VDC, -5VDC, and +3.3VDC. Depending on the quality of the supply, these voltages may be produced independently on different "rails" or on two or 3 independent rails with inverters and step-down transformers. One rail may go and you lose only the -12VDC for example. The fans will still spin and maybe even the HDs will spin. But that does not mean the correct voltages are present where needed.

The LED on the motherboard merely indicates voltage is present - that is a warning light saying "Hey stupid, unplug the the power supply before inserting or removing RAM!"

Note too that on ATX motherboards, if the CPU is blown, you get the same indications you got!

Power supply checkers plug into the big ps plug and will indicated if ALL voltages are present and close to within specs.