UPDATE: A21m won't hold cmos settings and LCD compatibility.

[thinkpadcollection]

If I can find this cmos power problem on mainboard let anyone know but if do have experiences with these issues also let me know, already tried new CMOS battery.

Also this also has a yellowed 14.1" LCD what LCD is compatible from any thinkpads? If not. I'd seek out another thinkpad 600X parts even complete one with bad LCD or complete 600X base will do. I do not like the A21m anyway if things is too much to do.

UPDATE:

Checked and found the bios battery to be good and tested connection on motherboard's side with meter, voltage is present and on the hunch tested computer overnight without main battery. No problem now, why this main battery could do this?

Again, what 14.1" LCD panel I could take from any certain thinkpads?

Cheers, thinkpadcollection

[danikayser84]

I had a similar issue with an A22p and a X21, where if the main battery was present sometimes the CMOS battery would not be working properly; out of curiosity, what version is your BIOS and EC? Try upgrading it and see if there's any change in behaviors

The 14.1" panel is the same connector as in A2*m (XGA 14.1), T2* (XGA 14.1), A3* (XGA 14.1) and maybe some others too (at least according to this article on ThinkWiki

[rkawakami]

This doesn't seem to apply to the problem described earlier but it may shed some light on how/why the CMOS battery works (or doesn't).

Looking at some documentation for a T20 system (which might use a similar power system design to the A21m), the CMOS (aka, Real-Time Clock, BIOS or backup) battery is shadowed by another 3V supply on the motherboard. This essentially means that as long as the AC adapter is connected (the system does not need to be turned on), the CMOS battery is superfluous.

There is a diode and resistor which prevents the AC adapter from "charging" the CMOS battery as it is definitely not rechargeable. There's also the same kind of diode inline with the motherboard's 3V supply. That prevents the CMOS battery from powering whatever else is connected to that supply (in the absence of the AC adapter or battery). Depending upon where you measure the CMOS battery on the motherboard (probably right at the tiny connector), you could see the proper voltage from the CMOS battery but if the associated diode or resistor is open, the 3V from the battery won't get to where it's supposed to go; the system will lose time if the system is turned off and AC adapter removed.

Disconnecting the AC adapter (and main battery) would be recommended if you are attempting to measure the CMOS battery voltage directly on the motherboard. An open diode or resistor would explain the case where the system keeps time as long as the AC adapter is connected, but if removed and a known good CMOS battery is installed, the system still loses the clock setting.

It appears that if only the main battery is connected and the system is off, it does not supply any power to the RTC circuit like the AC adapter does. Only when the system is turned on will the 3V motherboard supply power to the RTC.

[thinkpadcollection]

One more thing, now that I have this sorted out, is why is this PIII-M is stuck at 650MHz instead of 800MHz? Does this caused by dead main battery or not installed? If true, that is extremely annoying.

Cheers, thinkpadcollection

[rkawakami]

Yes. I believe that this is common "feature".

[danikayser84]

One more thing, now that I have this sorted out, is why is this PIII-M is stuck at 650MHz instead of 800MHz? Does this caused by dead main battery or not installed? If true, that is extremely annoying.

Cheers, thinkpadcollection

Yes, unfortunately on this era of ThinkPads, if you run them with a dead or without the main battery, they will be locked at the lower speed (such as 500MHz for a 650MHz, or 1.2GHz instead of 2.0GHz); third party batteries may also cause issues (I know it did on my 600X and T23 so I went and looked for genuine used ones... even if they hold barely any charge they will still let the machine run at full speed; even a 10-minute or less battery is good to act like a UPS)