Toshiba A500 -yet another strange fault

[tw2005]

I have another Toshiba A500 . PSAR3A-026002

KSKAA LA-4991P Rev. 3.0 mainboard

2 x 2GB PC6400 DDR2

P8800 2.66ghz 3M cache Core Duo.

Purchased broken, advertised as broken screen but in fact had broken fascia glass and broken LVDS cable, screen is good , display was all lines but external monitor works fine.

Initially I had an issue getting it to boot to bios, usual RAM swap got it going. I was in 2 minds whether it was the stick or slot but ran with 1 and eventually I tried both slots and it seemed ok.

using an external monitor, loaded OS(W7) and was ok except it became a nightmare finding Digitally signed drivers.

Then I was going to try Vista instead and somewhere along the line it started having issues like getting to splash screen and just stayed there, suggesting it was still loading. The HDD light was not active.

I tried Hirens mini xp, it does the same as windows.

It will run linux and DOS programs from Hirens.

I can get into bios and change settings.

I have tried loading defaults and also disabled dual core, no change.

have tried 8 sticks of RAM including a known good set from another A500.

have tried 4 different HDD.

Memtest 86 runs in Dos, no errors with 2 simms installed.

it seems quite apparent I'm looking at MB issue and I 'm thinking it's along the memory addressing but honestly not my area of great knowledge.

I did on one occasion fluke getting Hirens mini XP up after about 2 hours of RAM swapping etc, but once I remaoved that piece to the alternate slot, back to the same problem, going back again to the first slot, no good . spent hours again tryin and could not replicate it working again.

It's frustrating it almost works but not where it needs too. Hoping there's a chip that's replaceable rather than the whole MB.

Also, have swapped the P8800 with a T6500 CPU 2.1 known to be good, no change.

there's a possibility this has had moisture ingress or been in a moist environment as I'm seeing a white build up between the legs and pins of devices on the board. I've had one go with a brush and alcohol, but no luck there.

Sorry, but I'm clueless again

[tw2005]

Re: Toshiba A500 -yet another strange fault- runs dos/linux only, hangs on windows-

I think I'll have to post my problems more often. Must clear the head but I think I've worked it out? Not sure if this is when everyone gets a giggle on but a small bit of info missing from post #1

I completely removed the LCD screen and cable, swapped a lid from my other to prove it was cable, decided whilst i was waiting for parts to leave the screen disconnected using ext mon only.

It was the only variable left, I was not going to try it but I was stuck. reconnected the screen (faulty cable), put it through a reboot, hooked up the external, another reboot and strike me dead it's booting mini xp as it should.

shutdown and cold start, worked, shutdown, removed lcd cable again, and a hung mini xp startup.

I bet some smart cookie out there has struck this but some of the simplest induced faults are simply frustrating.

[tw2005]

Re: Toshiba A500 -yet another strange fault

unbelievably, I'm back to square one. Put the original RAM back, and HDD and hangs. Bios has hang twice too. swapping RAM and no chance.

Can bios cause this?

[selldoor]

Re: Toshiba A500 -yet another strange fault

Cmos battery good?

[ktmmotocross]

Re: Toshiba A500 -yet another strange fault

what about working ONLY on battery

[tw2005]

Re: Toshiba A500 -yet another strange fault

Cmos battery good?

3V so ok

[tw2005]

Re: Toshiba A500 -yet another strange fault

what about working ONLY on battery

I think I've tried that, I'll try again. I've fluked it again but can't get the ball rolling for a HDD reload.

i assume your thinking along the lines of a bad cap or dirty power causing issues? I did disable one core with no joy as I was wondering along the lines of the A300 proadiliser issue which this does not have.

[tw2005]

Re: Toshiba A500 -yet another strange fault

what about working ONLY on battery

No joy I'm afraid.

[tw2005]

Re: Toshiba A500 -yet another strange fault

well it's back again and this time I hooked up a small LCD TV via HDMI. Recognised it then booted and recognised hirens, shutdown and booted the HDD as well. Just trying a second go at W7 64 which I expect still to have issues installing drivers but I'm fairly confident now that once I get the new screen cable and have it assembled this is probably going to be ok.

No doubt I've created a situation which is not normal.

I'll report back with a final conclusion I guess when it's re-assembled.

[dj_ricoh]

Re: Toshiba A500 -yet another strange fault

yesterday i was working on a l450 same thing.

dead mobo. swap with mine; i was testing screens with this motherboard. i only had bottom case,screen cable out and invertor.
when i move everything in there ofc my cables no, it power up saw l toshiba logo then shutdown. if keep insisting it will not display.
screen bezel was a little bend so that was my hint for "what the hek"

[tw2005]

Re: Toshiba A500 -yet another strange fault

looking like bad MOBO, still have issues(cable replaced) and now has display issue with internal output, ext ok. I did something silly assuming same panel and connector from another Toshiba a350 would be ok for quick test, shorted or sent voltage somewhere bad, killed a good panel, onboard lights ( they fire up backlight turn on) now don't work on MOBO plus incorrect display. My bad. now faced with the dilemma just MOBO and or graphics card as well. External output good.

Tried a different rev mobo / AMD graphics and had no issues with W7 drivers or performance, that's where I'm at.

Board killed had Nvidia

No idea what I would need to repair board, not my strength and I have no schematic.

Now expensive repair from here.