Possible Power Supple Issue

M

MarkGarth

Member
Hi all

I think I might have the early signs of a PSU fault. When I turn on the PC the HD activity light flashes very quickly and nothing else happens (no POST, video etc). The only way to get the machine on is to switch the power off at the rear and hold the front on button (the activity light flashes briefly as though discharging residual power). Then switch the rear power back on and the front switch then works fine.

Once on, the PC is fine and shows no other symptoms (it will do a restart ok).

My guess is either a failing capacitor or something to do with the PSU start signal????

Any ideas before I open the case and try a PSU tester (I'm still in my 2 year warranty)?

On a second note, I have to say that despite always building my own machines before I got this one, this one is the best!

Mark
 
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PCS

PCS

Administrator
Staff member
Has this issue just started to happen?

It does sound like the PSU but normally when a problem like this occurs it's present from day one.
 
M

MarkGarth

Member
Yesterday was the first time it happened and now it does it every time you do a complete shutdown. I got the machine from you in June 2009 and it's worked without a glitch up until now.
 
PCS

PCS

Administrator
Staff member
Hmm, could be a hairline fracture on the motherboard too, as you suggested. I would suggest you open up the PC and clean the inside with air/anti-static cloth and re-seat some components if possible. Then try booting again. The problem may disappear, or get worse.
 
Gorman

Gorman

Author Level
If you have a PSU tester to hand, using that to rule out the PSU would be my first step. If it tests ok then you can move onto PCS's suggestion of further fault finding.

If its faulty on the PSU tester then its an easy win.
 
M

MarkGarth

Member
OK, I used a basic PSU tester (LED type), and with power connected and the rear mains switch off I just had the +5vSB LED illuminated as expected. When I switched the rear mains switch on, the +3.3v, -12v, +5vSB, +12v and +5v LEDs came on, but the PG and -5v didn't and the +5v was flickering very fast). I don't think many PSU's use the -5v anymore, but the PG and +5v seem a bit odd. Unfortunately, I don't have a spare PSU to use as a benchmark.

I’m still confused as the machine works perfectly once it's on, so maybe it's something on the PSU latching circuit. I could connect a DMM.

I carefully dusted and checked the seating of all the other connectors and the three memory cards. Everything else looked fine.

?????
 
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PCS

PCS

Administrator
Staff member
Hmm, sounds like it could be a faulty PSU. If you've like us to ship you a new one we are more than happy to. :)
 
PCS

PCS

Administrator
Staff member
RMA Generated: PK25003 will be dispatched to you on Monday for delivery on Tuesday. Please have the old PSU removed from your PC and packaged in bubble wrap/protective packaging so that our courier can collect this when delivering your new PSU. A text message will be sent to 07*******87 with the consignment number upon dispatch.
 
M

MarkGarth

Member
OK, firstly the new PSU arrived safe and well this morning and the old one is on its way back to you, so many thanks for a rapid service.

I did a quick test before installing it and this time the PG LED was illuminated and the +5v was steady, so I’m now sure that the old PSU had developed a fault.

Having installed the new PSU and cycled the power a few times, everything is fine.

Once again, many thanks for the online help and swift customer service.

Mark
 
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