TP23 won't start -- is my system board dead?

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poochtp23 · #1 Post by **poochtp23** » Sun May 20, 2007 1:22 pm

Hi,

I'm hoping someone here can help me diagnose this problem with my trusty old T23. I think it's serious -- but if it's a matter of replacing the system board (for $100 and *lots* of disassembly and reassembly), I'll probably try to save my old friend.

Here's what happens -- turn the power on, nothing ever gets displayed on the LCD. I've tried hooking it up to an external monitor, but nothing ever gets displayed there either (after cycling through Fn+F7 several times).

So at first I thought it could be a video card problem. I thought maybe it was booting up and starting WinXP and all that but just couldn't display anything. But then I noticed that the HDD access light was never going on, so now I'm questioning whether anything is happening at all.

I've checked in the IBM ThinkPad T23 maintenance manual, and looked at the "No-beep symptoms" because when I power up the machine, I hear no beeps, only the whirring of the fan. The first two symptoms there are "No beep, power-on indicator on, LCD blank, and no POST" and then "No beep, power-on indicator on, and LCD blank during POST".

Either one can apply to me. If the LCD is blank, how can I tell whether POST is happening?!

For the first symptom it says "1. Make sure that every connector is connected tightly and correctly. 2. DIMM. 3. System board." For the second symptom it says "1. Reseat DIMM. 2. System board."

As far as making sure *every* connector is connected tightly and correctly, that would mean taking the entire machine apart. I'm not ready to do that yet. I'm hoping there's another way to determine whether I've got a DIMM or System board problem.

So I started messing with the DIMMs. I've got two 512MB DIMMs in there. I remove one, then power on with the remaining DIMM in its original slot -- same symptom. Move the DIMM to the other slot -- same symptom. Try the other DIMM in each of two slots -- same symptom each time. Then I put back the long-ago shelved 256MB DIM that originally came with the machine -- same symptom.

It doesn't seem that a DIMM is the problem. But how can I be sure it's a system board problem?

Here's another possible clue -- when I powered on with *no* DIMMs installed, I finally got a beep sequence - 1-3-3-1 which the maintenance manual says is DIMM or system board. I think the problem in that case is that there is NO DIMM, right?

Anyway, does the fact that I get beeps without DIMMs mean that the system board is at least partially functional and/or that the POST is occurring?

Thanks very much for any help you can provide in diagnosing this!

. . . Phil

#2 Post by **rkawakami** » Sun May 20, 2007 4:56 pm

Phil,

Your diagnostic technique is sound. When presented with a problem that is not fuly documented in the HMM, then the remaining troubleshooting tip applies:

Remove all removable hardware and start booting. If it works, install one piece of hardware at a time until the system does not boot anymore. When that happens, you found the problem.

ref: http://forum.thinkpads.com/viewtopic.php?t=29949

truk · #3 Post by **truk** » Sun May 20, 2007 8:21 pm

If that doesn't work, and you have an extra one lying around, I'd try to switch to a known good CPU. I had the same problem a few years ago on a machine I thought had a dead MB, and it turned out to be a CPU issue.

poochtp23 · #4 Post by **poochtp23** » Sun May 20, 2007 8:28 pm

Thanks for the replies so far.

What conclusions can be drawn from the fact that I do hear the beep sequence if I remove both DIMMs -- does that mean the CPU must be alive and so the problem must be elsewhere on the system board -- or could the machine beep even with a dead CPU?

Thanks,

. . . Phil

#5 Post by **rkawakami** » Mon May 21, 2007 1:05 am

My bet would be on the modem or modem/wireless card. My latest 2647-4NU T23 ($80 on eBay) did exactly what you describe (no POST/display; removed memory and it beeped 1-3-3-1).

Website · #6 Post by **tfflivemb2** » Mon May 21, 2007 1:16 pm

poochtp23 wrote:<snip> I hear no beeps, only the whirring of the fan. The first two symptoms there are "No beep, power-on indicator on, LCD blank, and no POST" and then "No beep, power-on indicator on, and LCD blank during POST".<snip>

When you say "whirring" of the fan...is it a constant whir or a pulsing whir?

truk · #7 Post by **truk** » Mon May 21, 2007 5:30 pm

Yes, a computer can beep with a dead CPU. The beeps are controlled by the motherboard, and most will beep if they have no CPU.

vlyne · #8 Post by **vlyne** » Tue May 22, 2007 2:10 am

I'm not sure about the T23 but on a T20/21, if you don't have the CPU properly locked in place, you'll get a quick flash of the LED (a version of the so-called "blink of death") and nothing - I know this from experience. The fact that it beeps suggests it is trying to POST. It may get hung if there is a problem with the BIOS (corrupted, bad CRC) but this will take a couple of minutes or so before any message comes up. As suggested by Ray, I'd take off the network card and check the ports as well for bent contacts.
Cheers

phool@round · #9 Post by **phool@round** » Tue May 22, 2007 12:48 pm

There is a large coil near the processor that can cause the issue that you are experiencing as well as all the other fine suggestions. No video on LCD or VGA port, no disk drive activity, no single system beep at boot, etc, etc. System appears dead but there is processor fan activity and the power indicator is on. If the fan is steady then here is my two cents.

http://www.rkawakami.net/ibm_t2x/mobo_top_72_legend.jpg

The link is to a T23 logic board *top* with overlay Ray created to define logic board parts.

There is one missing large coil in A/1 of Ray's board pic that has three solder pads (you can see the three pads if you look closely). That (missing) part is the one I'm referring to. Check to see if it's still in place and completely soldered at all three pads.

Because of the processor cooling fan you'll have to remove the palmrest to see the coil. You might want to dismount your cooling fan while your in there. Check it for excess dust. If very dusty then I'd suspect the processor.

Memory as an issue seems to be out of the question especially since you did get the 1-3-3-1 beep. The board knows there isn't any memory.... and told you so.

The beeps are an indication that there is current flowing through the board and that's great news! It's not dead......just taking a nap.

poochtp23 · #10 Post by **poochtp23** » Wed May 23, 2007 8:43 am

Hi everyone,

Thanks SO much for the great suggestions. I'm working out of town this week and I don't have the machine with me, but I'll open up the patient this weekend and let y'all know what I find.

Thanks,

. . . Phil

poochtp23 · #11 Post by **poochtp23** » Mon Jul 02, 2007 3:14 pm

Hi,

It's been six weeks and I finally got the chance to do this work. I removed everything up to the system board, where I was able to see that the coil mentioned by phool@round was still intact. So I proceeded to put everything back together, hoping that the re-assembly would somehow right whatever had gone wrong.

And it worked!!! I am thrilled. And I wouldn't have undertaken the task if it wasn't for the support of this forum.

Thanks everyone,

. . . Phil