After dis/reconnecting my HP Pavilion T490 from the mains, the power supply makes a rapid ticking sound (several times a second) and the light on the back of the power supply flashes.

It happened a few months back too, after a vacation, but then, after a few tries, the PSU kicked in. After that time, I disconnected the power several times bu pulling the cord out of the socket. This time, and before going on vacation, I first switched of the Belkin Surgemaster before pulling the cords out of the sockets.

To resolve the issue, I tried disconnecting wires, PCI cards, etc, and the things that seems to do the trick is disconnecting the ATX plug from the motherboard. But that still leaves me clueless as to what is the cause. The motherboard or the PSU. From what I've read, it is either the overvoltage protection kicking in or a capacitator that fails to charge fully. I personally suspect the later, but not sure wheter it would be a capacitator on the motherboard or in the PSU.

Last time I checked with Speedfan, voltages, rpm, temps were all ok. Computer was stable, connected to a Belkin Surgemaster Gold,

I've googled quite a lot, and found people with similiar issues, but never an sollution

The flashing light on the back is surely telling you there's a PSU problem? It is normally on steady, isn't it?

The problem with searching for answers to this sort of problem is that often a lot of people don't consider having to replace the PSU as a solution - they're looking for magical software fixes and so they don't follow their threads through.

Do you have access to a spare PSU or a friendly computer store?

Hi SnowDog, thanx for your reply!

No spare PSU lying around and no friendly computer stores in the neighbourhood. The computer still has warranty, but last time when the HD broke down, it was away for 50 days and I can't afford that timewise.

The led on the back is normally on when the machine is plugged in the mains. When I unplug it, it goes off after about 10-15 seconds (under normal circumstances).

I found these two threads with are related to this issue:

http://www.techspot.com/v...n-on-and-its-ticking.html
http://www.daniweb.com/techtalkforums/thread35827.html

Ah. Well, under warranty you are quids in.

Unplug everything and let it stand for a few minutes - just the tower with nothing connected.

Plug in the mains and look at that led on the back.

Try powering up.

If it does anything odd then you have a fault that is definitely in warranty territory. Call them and get them to fix it.

Well , last time I used warranty (even bought an extended warranty plan), it took them 50 days to replace a HD (and they didn't try to make a copy of the old broken but slightly working one). Those 50 days cost me more than a new HD, motherboard or power supply.

Tried leaving it completely unconnected for at least an hour, no result. Also tried to use the HP power troubleshooting document, removed all cards and memory, pressed the powerbutton for 5 seconds with everything disconnected, chatted with an online HP-help employee (which couldn't help me further because I live in the Netherlands) ...

Well, better a 50-day wait than no computer, period!

That's just bad service, of course, and I can't comment on it directly - not knowing the full details.

If we book out an engineer (or part) to a customer it depends on whether the part is in stock or not. If it isn't, it often has to come from the manufacturer of the machine, and we are just as vulnerable to stupid delays as the customer in those circumstances. It is shocking when a new machine doesn't have spare available, but under terms of the warranty it has to be an approved part that goes back in.

Not many manufacturers - especially HP - deliberately take 50 days to fix things. It is usually much quicker and that last experience may have been extraordinary.

We can usually get repairs done inside a week.

I tried one other thing to further investigate the issue. It took the ATX loose, and the 4pin ATX cpu-power, and hardwired ATX pin 14 with a ground pin. The HD spins up, and the PSU acts normal.

I take it that HP normally provides better service, though I doubt it is at the same level as in the US for instance.

In the UK, it would be repaired within days.

It depends on your retailer's support structure. Often, if retailers have their own technical support they repair under licence in 12 month warranty. HP licences repair to 3rd parties anyway (especially laptops).

It isn't necessarily HP who is to blame for any delays.

I'm not saying that it is all HP's fault (offtopic anyway), though I did purchase a brand computer for a reason (including extra warranty). Plus, the HD died on me within a year and mine was no exception. That is what really bugged me. They should have led me know I had a faulty HD and replaced it before it died.

But on-topic; Is there any test I can do to further narrow down the problem?

You can't really narrow it down any more than you have!

PSU error light with nothing else connected? So a PSU fault.

And you have extended warranty? You're covered for everything except software!!!

If your diagnostic and repair system is anything like ours, it definitely has a fault and definitely needs an engineer out to it based on the symptoms you have and the tests you've done, so the call centre will book it (though I'm sure they'll insist on you trying something on the phone so they don't get caught out).

HDDs dying soon after purchase is horribly common. Working in my call centre I have developed a sort of phobia about 200GB HDDs (and 160GB ones to a lesser extent) - they appear SO unreliable.