HP Pavilion: Power Supply ticks / LED on the back flashes; no boot

By Klaus_1250 ยท 12 replies
Oct 29, 2006
  1. After disconnecting and reconnecting my HP Pavilion T490 desktop to the mains, it refuses to start. The PSU makes a ticking / clicking noise and the LED on the back flashes / blinks. A few months back, after returning from vacation, I had the exact same issue, but it worked after a few tries.

    I worked through the HP Power Supply troubleshooting doc and talked to an online help employee. The PSU fails to work as soon as I plug in the 20 pin ATX-connector in the motherboard (both with and without all PCI/AGP cards and memory modules). If I hardwire ATX pin 14 to a ground pin, the HD and CD/DVD's spin up.

    After all these test, I'm still not sure what the problem is. The PSU or the motherboard. The machine still falls under warranty, but, if it is the PSU, I'll replace it myself with a higher quality higher wattage model (currently is a Bestec 250W ATX). If it is the motherboard, I'll use the warranty (aren't any shops here which sell microATX socket 478 SATA/Firewire boards anyway).

    Anyone got a clue what the issue is here? I've googled arround; found similiar problems, but never definate answers as to what is the problem.
  2. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Hello and welcome to Techspot.

    As far as I can tell, that sounds more like a mobo problem than a psu problem. In any case, as you system is still under warranty, I suggest you let HP take care of it.

    Let us know the outcome please.

    Regards Howard :wave: :wave:
  3. Klaus_1250

    Klaus_1250 TS Rookie Topic Starter

    Thanks for the reply. I'm a bit reluctant to use the warranty. When the HD died on me, just after 8 months, it took them 50 days to replace it. I can't afford to miss it that long. And before I can turn it in for warranty, I need to make a complete backup of the HD and clean it as it contains confidential information. Hence, I'd rather try to fix it myself if possible.
  4. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Sounds like you`re stuck between a rock and a hard place. Your only choice is to try another psu. However, I have my doubts as to whether that will solve your problem as I still think it`s more likely a mobo problem.

    On the other hand, it`s always handy to have a spare known good psu for troubleshooting.

    Regards Howard :)
  5. Klaus_1250

    Klaus_1250 TS Rookie Topic Starter

    I will try to see if I can borrow a PSU somewhere. For completeness, the PSU is a Bestec ATX 250 12Z Rev. C Accorinding to one post, some of the Bestec PSU's are prone to have issues with the +5VSB (???) line.

    Also googled the following links which relate to the issue (no definate anwswers hoewever):

  6. Rik

    Rik Banned Posts: 3,814

    If i were you i'd ask them for my money back then go out and buy a decent pc!!!! I have recently had to deal with a few of those pavilions and i have to say they arent much good!!!!

    They are that bad that they only just rate above sony vaio's which are THE worst pc's on the market today!!!!
  7. Klaus_1250

    Klaus_1250 TS Rookie Topic Starter

    In hindsight I wouldn't buy one either anymore. Since the Pavilion is now a little over a year old, I can't return it.

    In any case, a small update. I went by a friend, opened his computer, pulled of the ATX connecter, put an ATX extension cord on it, and plugged it into the Pavilion. I pushed the power button and all fans started spinning. Becaused my PSU also worked by hardwiring ATX pin 14 with a ground pin, I suspect that either the PSU's overload protection is broken or it has a problem supplying a non-12V voltage line. In one post I read that the +5VSB line in Bestec PSU's is prone to problems. Will go off and buy an new high quality 350-400W PSU on Tuesday.
  8. Rik

    Rik Banned Posts: 3,814

    I would bet the 5 volt regulator has fried up!!! I suspect they use the absolute cheapest voltage regulator they can find!!! I used to work in the electronics trade and have seen things like that happen often!!!!
  9. Klaus_1250

    Klaus_1250 TS Rookie Topic Starter

    What are the chances that a bad voltage regulator damaged the motherboard or PCI-cards?
  10. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    There is a chance that a faulty psu could`ve damaged other components. However, without trying a different psu, it`s impossible to tell. I hope not in your case.

    Regards Howard :)
  11. Rik

    Rik Banned Posts: 3,814

    There is a possibility it has done damage and there is a possibility it hasn't!!!!

    The only way you will know is to get a better psu in there and try everything!!!!

    Sorry, Howards post didn't show before i posted mine!!!!
  12. Klaus_1250

    Klaus_1250 TS Rookie Topic Starter

    Plugged in my new PSU today (Coolermaster iGreen 430W, slightly overkill): problem solved :-D No apparent damage to the motherboard or any other components. Thanx everyone for your help/advice!
  13. Rik

    Rik Banned Posts: 3,814

    I'm glad you got it working!!!! :)
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