R52 only works when LCD is unplugged

[fasterbybike]

I've just acquired a R52 (1858-6SM here's the spec).

It was sold as a faulty unit with the symptom "Turn on and goes off again".

That's how it arrived - turn it on and all the LEDs light for a couple of seconds, the fan is spinning and then it goes off. I had to unplug/replug the power adapter to restart.
I tried all the usual tricks of removing all plugin boards, CMOS battery etc, swapping the RAM in different sockets but the same symptom occurred.

I then unplugged the LCD cable from the mobo and plugged in an external monitor.

Now it boots up

What should I look for to fix this ?
Alternatively I could run it as a desktop replacement with an external monitor always connected.

[RealBlackStuff]

A new LCD cable comes to mind...
(after you check that it is plugged in properly on the back of the LCD)

[fasterbybike]

I'd had time to disassemble and take another look ...

The complete lid works on a T40 ...

When I connect only the cable back to the R52 (cable removed from the LCD and inverter) it exhibits the sudden stop symptom.

My guess is that the mobo is busted - it works OK with an external display and is no good with the LCD connected.

BTW, this has a mobo with Intel 915 integrated graphics. So the Intel ones do fail, maybe just not as often as the ATI ones.

I'm going to run this one as a headless unit with a permanent connect to my desktop monitor.

D

[ajkula66]

I know that this is likely a far reach on my part, but there might be a mismatch when it comes to the cable...

Not that I've ever tried it (at least I don't remember doing it on purpose), but in my book (or my warped logic, take your pick) LCD cable for a 15" XGA unit (R52) should not be working with a 14" unit (T40) without major distortions if at all...

[fasterbybike]

Thanks George

The 15" LCD is now mated to the T40 for testing. I'll run PC Doctor on the R52 in the meantime to see if that shows any issues.

And the FRU on the cable is 91P6904 which corresponds to the correct part in the R52 HMM.

I think the mobo is the problem

[fasterbybike]

Well this is the strangest story I've yet come across ..

The EMI shield for the modem on this unit has a metal prong. This was bent up and contacting the traces on the LCD cable (adjacent to the plug) - thus shorting it out when connected.

I bent the EMI shield back to where it should have been - and now have a working R52.
An IPS SXGA+ LCD is on the way to replace the XGA unit.

And a new keyboard would be nice as this one is missing the delete button (pressing the blue rubber bung works tho). Also many of the key are covered with a residue of some type of adhesive. It appears the machine was adapted for a low sighted user. A real shame as it is a NMB version.

D