T20 mystery shutdowns, cmos?

[tokyo_x40]

Inherited a T20, delighted at the build quality, but sadly it won't stay on very long..

After a period of time between 20-60 min, screen goes black (even for memtest86+) and machine is unresponsive. Happens whether main battery is inserted or when under AC only. Two LEDs remain illuminated, the main power one, and the far left "tray area" indicator, best described as "right-arrow-X". System unresponsive to any keys, including the power button. Except: hitting the power button multiple times leads to what sounds like a "too many keystrokes" beep.

I noticed that the date was set to 1999; are the random shutdowns the result of a bad CMOS battery? (I always thought they got power/charged from the AC) Since screws near the CMOS battery bracket are missing and the CMOS battery is visible when ejecting the main battery, perhaps I'm not the first person to wonder that.

Any cheap DIY ways to fix this, or are IBM parts strictly required?

Thanks

[sjthinkpader]

Remove the fan and reapply heatsink compound. You may need CMOS battery as well.

[RealBlackStuff]

I agree with sjthinkpader on both accounts.
The T20 is most likely overheating, and has a near-dead CMOS battery (CR2032).

[tokyo_x40]

Thanks, sounds like I should try the heatsink compound first. My first time doing this, will google for instructions/brands

The T20 is most likely overheating, and has a near-dead CMOS battery (CR2032).

I read that battery leads are welded to the T20 oem cmos battery unit. Can anyone confirm this, or would a drugstore CR2032 be possible? I'd have to strip the yellow plastic heat-shrink to check mine, prefer to wait.

[Neil]

Yes, the leads are soldered onto the battery under the yellow sleeve. A CR2032 will work if you can solder the leads to it. Or, you could take the leads off the old battery and tape them to the new one (contact will not be good though, best to solder).

A proper replacement battery won't cost you any more than the drug store one, it will just take a few more days to get it.

[RealBlackStuff]

If you set the date, and at the next cold boot the date is back to 1996, then your CMOS battery is definitely dead.
You can NOT solder contacts onto those CR2032 batteries, but taping will do if you can't get an original. Like Neil said, get a complete one (off e.g. eBay).

[Robbyrobot]

@Neil:

A proper replacement battery won't cost you any more than the drug store one

In that case, your drugstore must be a very expensive place indeed. I generally replace the CMOS batteries by pulling off the welded - not soldered - contacts and taping them (with plastic electrical tape, pulling it tight) on a new battery. No problems to date with that, although some advise against it.

It's inadvisable to solder contacts on a lithium battery, since this often leads to nasty explosions. The original contacts are spot welded, and the heat is restricted to the contact and the surface of the battery. However, you need special equipment to do this yourself.

[tokyo_x40]

Remove the fan and reapply heatsink compound.

New compound had almost no effect.

What does "almost" mean? Now after 40 minutes the machine powers off completely--it no longer hangs with the power LED and "arrow->X" LED stuck on. In case it matters, the previous heatsink compound was a grey solid rubber-like square pad, and I applied one diagonal line of standard cheap white "silicone base" heat sink compound. I kept the grey rubber thing, in case it would be better.

(I also noticed that the chassis screws for securing the keyboard are missing. I mention this in the off chance they are used for grounding/etc)

Is there a way to test the fan, in case it is bad? Is memtest86+ really that CPU intensive?

PS Thanks for the discussion on the CMOS battery, still haven't touched that yet. I'll likely try tape