Desktop dead - please help to isolate problem

ashleyg · 05 Jan 2013

I have been asked to look at fixing my brother in law's desktop PC, which will not power up.

The system is:
Compaq SR5840AN
Intel Core 2 Duo E7300 (2.66)
Mobo: MSI MS-7525 BostonL
PSU: 300W
Age: 2009

When I press the power on button on front of the case, there is absolutely no sign of life - no power up, fan spin, no beeps, nothing.

The PSU shows power is coming in as the pilot light on the back of the case (psu) is green.

I have reseated all cables to the mobo, the memory sticks and removed replaced the cmos battery - no change.

I have taken the psu down to my local repair shop for testing and they confirm it is ok.

If I'm right, that likely means the problem is on the motherboard. ie the mobo or the processor is dead (or both I guess).

Before I commit to any expense, I'd like to test somehow whether it is the proc or the mobo.

I don't have access to those spare parts to swap them out and test so am in need of guidance on the best way to approach this.

Thanks for any help with this.

**Pauly** · 05 Jan 2013

First thing i would do is disconnect everything take mobo out of case place on table with just cpu and fan attached to it and connect the two power connectors from psu to mobo 20/24 pin main power connector and cpu power connector 4/8 pin (if its got one) to see if you can get any life

bassfisher6522 · 05 Jan 2013

Pauly said:

First thing i would do is disconnect everything take mobo out of case place on table with just cpu and fan attached to it and connect the two power connectors from psu to mobo 20/24 pin main power connector and cpu power connector 4/8 pin (if its got one) to see if you can get any life

Not to horn in...but with your suggestion, what will this tell us...just curious.

**Pauly** · 05 Jan 2013

That mobo is not shorting out to pc case or short circuit in other component (HDD,GFX etc) is not affecting supply voltages/psu
Does the pc have a mobo speaker attached, does it or did it should i say used to beep when turned on

ashleyg · 05 Jan 2013

Cheers for prompt response!

I might need to park this for a week. BIL has advised that given he is up for some expense that he will look at returning the system for a replacement - it was purchased fairly recently as ex-corporate machine coming off lease and he says he has a pretty good chance of getting them to take it back and swapping it for one that is working. Hmm not sure as this one was working when he got it, but will wait and see.

On that basis, I can't go ahead and start disassembling the machine or they won't consider his request for a swap.

As far as the Mobo speaker - yes there is one on-board but he has a couple of machines and can't recall specifically whether this system beeped when it used to start up or not.

Thanks for your suggestion Pauly, I'll put it on the list if I do get the go ahead to fix the thing.

Unfortunately I'm a bit limited in what I can do at this stage - shame as I was up for the challenge!

I should know which way it's all going in about a week.

Cheers.

DocBrown · 05 Jan 2013

Sometimes the OFF/ON switch on the case breaks & therefore will not power up the motherboard, etc. I have bought replacement switches off eBay. Sometimes I have switched it with the Reset switch as they can be the same switch in some instances