tx2500 tablet CPU failure - reseated CPU, BIOS reset needed?

[giant_bean]

Hi everyone,

A few weeks ago my tx2500 started refusing to boot, with the one-blink Num/Caps LED error code that supposedly indicates CPU failure. When I try to boot, the screen is blank and the LEDs are blinking, but I can hear the fans spin up; I also can't get into the BIOS by pressing F10. After trying the unplug-the-battery trick and talking to HP support, I found the solution mentioned here which entailed removing/reseating the CPU. I disassembled the computer, removed the CPU and then reseated it along with new thermal compound. After putting everything back together, nothing changed: the computer still wouldn't boot and gave me the same error code. I guess the next step is to get a replacement CPU off Ebay; before I do that, though, does anyone know if I need to reset the BIOS after reseating the CPU to get it to work? Maybe to get the computer to "recognize" that the CPU has been removed? Doesn't seem likely, but who knows. If I do need to reset the BIOS, I can do that by removing the CMOS battery from the motherboard for a few minutes, correct?

Thanks in advance for your help!

Specs

tx2500z CTO Entertainment Notebook PC

AMD ZM-82 2.2GHz X2 Ultra

Windows 7 Pro x86

[ixtreme-repairs]

Hi there

This reply may be a bit late... hope you have managed to repair your laptop? We are a laptop repair company here in the UK which deals extensively with motherboard repairs. We have come across quite a few TX2500 models with AMD RADEON IGP 216-0674022 GPU chipset that have had the very same symptoms that you describe. All the ones we have repaired have had the same CPU - AMD Turion 64 X2 ZM-80 2.1 GHz Core Duo TMZM80DAM23GG. We have also tried removing & reseating CPU but this has never solved the problem. Resetting BIOS or removing CMOS battery will not make any difference either. It would be advisable to update the BIOS to latest version once you have fitted a new CPU though if it hasn't been updated already.

It seems like the overheating damages the CPU every time and in some cases damages the GPU (this is usually repairable by reflow repair or by having a new GPU fitted). In rare case we have had both the CPU & GPU fail. The GPU failure is very common in the earlier TX1000/TX2000 series as well with nVidia chipsets, in fact with every other series as well DV2000/DV6000/DV9000/G6000 etc.. This seems to be one of the only models with a very high rate of CPU failure.

We have found the best solution is to actually modify the fan to constantly run at a higher speed. This does make the laptop run quite a bit louder & does drain the battery faster, but will prevent future overheating and failure.

We have also found that using a copper shim along with Arctic Silver 5 or Arctic MX-3 thermal paste instead of thermal pad which is currently used between GPU & heat sink will help reduce temperatures by up to 20%!

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Thank you

[tbrown3177]

On the motherboards that had the CPU failures did you notice if the LEDs where flashing two quick times every few seconds?

[giant_bean]

Sorry for the slow response: on my tablet, the num lock and caps lock LEDs flash once every ~4 seconds. According to HP's troubleshooting guide for my tablet, it supposedly indicates CPU failure.

[Hp-tx2500-user]

Hi.

Did you solve your problem?

I have the same problem with my tablet. I ordered new cpu from e-bay. Hope, it will help.

Thanks in advace,

Alex.

[javos]

Hi,

Exactly the same problem I have with my tx2550ed (one-blink Num/Caps LED error code that supposedly indicates CPU failure. When I try to boot, the screen is blank and the LEDs are blinking, but I can hear the fans spin up; I also can't get into the BIOS by pressing F10).  I bought this notebook  end 2008. I can't accept the situation so I am thinking of buying a new cpu of Ebay. That is $ 200 with no guarantees for a working notebook - quite a risk. I would like to hear something from people who replaced the cpu. Giant_bean did it work out for you?

[giant_bean]

Hi javos,

Installing a new CPU (bought on eBay) did not work, at least in my case. It has been a while, but I'm pretty sure the blinking LED error code was the same after installing the new CPU.

After that, I tried a trick I found online (can try to dig up links if you like) that involved disassembling the laptop and applying heat and pressure to the integrated video chip on the motherboard. This method worked for me, sort of -- I had to leave the laptop on continuously because (almost) every time I put it in sleep mode or shut it off, it would refuse to boot again. I could get it working again with another round of heat/pressure, but this became a huge pain really fast.

However, this made it clear that the video chip was the source of the problem, so I bought a new motherboard (about $125 on eBay) and the laptop has been working fine since Aug. 2010. There are also repair services that will resolder the video chip on your current motherboard for slightly less money than the cost of a new one, if you want to go that route. In either case, I would recommend that you replace the foam-like "thermal pad" between the video chip and the heatsink with a thin copper shim before using the laptop very much, in an effort to keep temps lower in the future.

Hope this helps, and that you can get your laptop working soon -- I remember how frustrating it was when mine was down. Let me know if you have other questions!

[javos]

Thanks Giant_bean,

Your experience confirms the impression i got from my internet research that it's problably the video chip causing the problem. I found a good clip on youtube - and i'll try the heat/pressure method. 

Good to hear that a new motherboard worked for you, so i will have an alternative when the heatgunfun isn't the definitive solution. 

Thanks again, this is very helpfull!

[j_mac]

Hi Giant Bean,

My tx2500 has had graphics issues for a couple of weeks. Namely, I could not access an external monitor. Today I think the entire graphics card finally stopped working entirely. The screen is completely black. Strangely, I am not getting any blinking lights.

I am interested in trying the heat and pressure techniques you found on you tube. Can you forward the links? Thanks.

j_mac

[javos]

http://www.youtube.com/watch?v=ctHTF3oNdxI&NR=1

this is the video i found; i'll try this next weekend.

good luck!