T20 problem

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synchromesh · #1 Post by **synchromesh** » Mon Aug 27, 2007 11:01 pm

I have a T20 chassis which I was planning to build into a complete system. Sadly it has a problem which I can't figure out at this point. Maybe someone else had a similar thing happen?

I plugged the screen, RAM, processor + heatsink and keyboard in. Now sometimes it boots just fine. But sometimes it won't boot up. Basically what happens is when I push the on button on the keyboard, the hard disk LED lights up for a second, then it turns off and that's that. There is also an LED on the motherboard close to the right hinge (near the external keyboard jack) that lights up at the same time too and then turns off as well.

This happens several times in a row and then sometimes machine will boot. Yesterday I got it to boot several times in a row but now it won't boot 9 times out 10.

I know the CPU is good, I even tried several of them. Tried 2 different heatsinks, one from T21, one from T22. I know RAM is good and screen doesn't matter but it should be good too. Power supply is a good one from my T42p. Any ideas on what this might be?

jamerslong · #2 Post by **jamerslong** » Tue Aug 28, 2007 12:21 am

have you tried reseating everything?, did you make sure your screwed down the ZIF slot for the processor and reseat all of your connections?

i had this problem when i forgot to screw down the ZIF slot, it's tough to turn.

synchromesh · #3 Post by **synchromesh** » Tue Aug 28, 2007 12:30 am

jamerslong wrote:have you tried reseating everything?, did you make sure your screwed down the ZIF slot for the processor and reseat all of your connections?

i had this problem when i forgot to screw down the ZIF slot, it's tough to turn.

One of the first things I've done. Made sure all the connections (especially power) are tight and made sure the ZIF screw is in right position. This isn't it.

I'm leaning towards a faulty mobo but I hope I'm wrong.

Robbyrobot · #4 Post by **Robbyrobot** » Tue Aug 28, 2007 12:46 am

This kind of thing is apparently not that rare, and I also have a T21 with the same symptoms. It will boot normally for a week or 10 days, then suddenly will show the kind of symptoms you describe. Then if I push the "on" button, keep it pushed, then insert the live AC power adapter jack, it will usually boot normally again - at least for a while. Strange business, and there doesn't appear to be a general solution. Probably something to do with the mainboard, as you suspect... but what? Of course I've also reseated everything I could, including removing and replacing the CPU and the fan/heatsink.

#5 Post by **rkawakami** » Tue Aug 28, 2007 1:34 am

synchromesh · #6 Post by **synchromesh** » Tue Aug 28, 2007 9:03 am

Thanks, I was afraid of this. Granted, I only paid $25 for 2 motherboards but they're completely useless now. Oh well...

Robbyrobot · #7 Post by **Robbyrobot** » Wed Sep 12, 2007 1:40 pm

http://forum.thinkpads.com/viewtopic.php?t=47593

That was me, and in the meantime I'm the "proud owner" of two T21s with the same "BOD" problem

One - the one I originally wrote about - I bought in that condition (cheap and described as "defective"), and I was overjoyed for a short time when I found it would boot after all. Then it stopped booting for a while, then started again. At the moment, it boots quite nicely.

The other one I made myself

by installing a purchased mainboard (also cheap and described as "defective") in my T21 with a defective backlight (external monitor OK, backlight problem not due to the display). I was similarly pleased when this "repaired" T21 booted without problems afterward, and the LCD screen worked perfectly. Unfortunately, that only lasted around two days and now the computer also exhibits the familiar "BOD" symptoms (slight "plop" noise, momentary flicker of the HDD and battery lights when the "on" switch is pressed, otherwise no reaction).

My trick of holding the "on" button down while inserting the live AC power supply connector (without a main battery) unfortunately didn't work, so I've disconnected the AC power and will leave the computer until tomorrow without anything except the CMOS battery to see if I can start it then.

Edit: Next morning I held the "on" button down, inserted the live AC adapter plug... and the T21 started as if there had never been any problem. Go figure

I have the impression that this particular T2x problem is very widespread, and since it is intermittent is nearly impossible to diagnose and thus solve. The nasty part about it is that even buying a new/used mainboard (at a price generally amounting to at least half of what the whole computer is worth) is not a real, permanent solution since the same thing can happen with the new board after a week or month of normal operation.

Robbyrobot · #8 Post by **Robbyrobot** » Fri Sep 14, 2007 4:37 am

Meanwhile, neither one of my T21s will start, and I keep thinking about the noise I hear when I plug in the live AC adapter plug and simultaneously hold down the "on" button. Like I wrote, it's just a soft "plop"... what could cause that? If anyone can localize that, perhaps with a stethoscope, it would be a logical starting point for component replacement or reflowing of solder connections. As common as this defect appears to be, there simply must be a solution.

T20 problem

T20 problem

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