Thinkpad 760XL flaky system board?

[that1nerd]

Sorry for the incoming wall of text, but I need some help with my Thinkpad 760XL. Although I'm new to the forum, I'm not a newbie when it comes to troubleshooting PCs. Yet, this Thinkpad I purchased on eBay has me stumped.

It was working great for several months, but for whatever reason, it now seems to cut out when it attempts to boot from a drive. And when I say "cut out", I mean the whole system will shut down, the LCD screen goes blank, the hard drive spins down, and the power switch becomes unresponsive. All it will do in this state is let out two consecutive beeps when I push the power switch. Occasionally, I'll see an "8d" or "12d" on the keyboard LCD display. The only way to get it to boot again is to do a hard reset, by pulling the battery and AC adapter. It'll come back up, show the splash screen, and attempt to boot from the hard drive, only to repeat the process all over again.

I've ran diagnostics from "Easy Setup" several times, yet it doesn't report any errors. I've tried swapping different drives, different system board components, the system boards themselves, I've even gone as far as buying two more parts units off of eBay in an attempt to isolate a single component to the problem. (If you noticed that all the $50 and below units listed suddenly disappeared recently, that was me.) At this point, it's looking like this was all a fruitless (and expensive) endeavor. All attempts to update the firmware end in failure, because it will not boot to the System Maintenance disk.

There is also another problem, which I think it might be a symptom at this point, but it will no longer charge the battery. It'll run off of the battery no problem, but it will not charge it. I've tried different batteries, different AC adapters, swapped the DC board with the two others that I pulled from the parts units, yet there is no improvement. When I first boot the laptop, the keyboard display shows that it begins to charge the battery, but then stops a few seconds later. The battery indicator LED keeps blinking orange.

At this point I'm thinking its a flaky processor/system board, but I'm open to opinions. So does anyone have any suggestions?

[Norway Pad]

Hi and welcome to the forum. Except it's sad that it's problems with your legacy Thinkpad that brings you here.

I have no suggestions as to what the reason for this problem might be. But when I see that you have purchased parts units and swapped almost the entire computer, I am tempted to ask if you are sure that you have swapped in working parts? I assume you bought non-working parts units. Do you have a known working unit you can take the systemboards and all connected parts from at once? I say connected, as I assume a short or some other general failure in a connected component in your old computer can affect the systemboard, or in worst case even damage another systemboard that is swapped in. I also assume you have tried another RAM module?

Good luck, keep us posted.

[that1nerd]

Yeah, I've literally swapped around almost every part, including the RAM. All of the RAM sticks and other components I swapped around tested okay during diagnostics, though. I might end up spraying the contacts, to rule out a dirty connection, but I feel like I'm grasping at straws at this point.

The parts units I bought were "untested", but didn't look to be abused or heavily damaged. I figured at the time that they were working systems that were shelved years ago, and that there was nothing wrong with them, save the usual issues like dead batteries.

[Norway Pad]

Ok. Including the LCD and/or inverter? If the parts units are complete units, maybe one of them can be turned on and booted up with your old harddrive installed? I don't know, but it might be the next step to actually verify one of them. If you can swap a known working system board into your unit, and it still doesn't work, you have ruled out a major component. Just suggestions, you have probably already thought about that.

Also note that I have no experience with the 760 series, so I don't know if there are any pitfalls or known failures there, like the T4x and T61 GPU issues, or the T21(?) 'blink of death'. Others might have to fill in that part.

[that1nerd]

That's what I was hoping for, actually. For someone to hop on and say something along the lines of "I've seen that problem before", and to suggest a few specific tricks that I don't know about. I appreciate the help, though.

[that1nerd]

Well, good news finally!

I ended up getting my hands on a fully working 760XL, and I was able to confirm that both of the system boards I have are bad. BOTH. What are the odds of getting two flaky system boards in a row? All of the other components tested fine, so at least I have a working system again...

...and enough spare parts to rebuild it twice!

Now that I'm back at square one, I can finally install Windows 95 like I was planning on in the first place, but I don't have any of the original software. Would anyone happen to have an ISO copy of the recovery CD-ROM that I can download? I'd rather download and burn it then have to pay for shipping.

[Norway Pad]

Good! Happy to hear that you at least got a system back up. I was strongly suspecting that some of the untested parts had to be bad, judging from the extensive swapping you had done.

[that1nerd]

I don't mean to bump an older thread, but I'm posting this just in case someone out there has a similar problem, and happens to find this.

I finally figured out what was going on here, so I'll give a quick recap on what's going on. I have two 760XLs and a 760XD. All but one of these laptops had the problem described above. This took me a while to realize, but both laptops had one thing in common; I had pulled the keyboard card.

Why this is relevant to my issue is because said keyboard card has a momentary switch on it that triggers sleep mode when depressed. This is part of the cutout for when someone "pops the hood" while the laptop's powered on. Well, because of my inexperience with these Thinkpads, and my notoriously heavy-handed method of servicing laptops, I managed to shear the small plastic pin of said switch. On BOTH laptops. Obviously, because there's nothing to push the switch closed, the laptop thinks the hood's still open even though it's closed completely.

When I finally realized this, I booted up my 760XD with the palm rest removed, and inserted a small screwdriver into what was left of the switch. Lo and behold, it booted into Windows, no problem. Thankfully, I had a spare card with an intact switch, so I was able to get the XD up and running again, but my second XL is still out of commission. Either I'll get a replacement board for it, or I'll bypass the switch altogether.

In the end, all I can say after this "experience" is to be VERY mindful of the switch while replacing the standby battery, and keep in mind that the speaker headers like to pop loose. If you attempt removing the keyboard card, keep a soldering iron handy.

[Norway Pad]

Good job on finding it, and also for posting. That's the kind of feedback we need for this forum to be a look-up for problems like this.

[Saucey]

Not bad, so you got one for parts now and a second one running like a madman, third for parts.
I'll keep that in mind on my units that don't want to boot.
Interesting indeed.

[that1nerd]

I actually managed to get all of them up and running, but I now have a ton of spare parts. (And two laptops too many.)

Hit me up if you need some obscure part for the XL/XD, and I just might happen to have it. I'll gladly work out a trade.