Thinkpad boot issues

[zx600]

I have a Thinkpad A20m that was working fine until two months ago, some day It didn't start again... I check the CMOS battery and it was about 2,7 V, I interchanged a CMOS battery from another TP, and suddenly it's started ok.
Then I supossed there was a Cmos battery problem and I bought and install a new one on my TP, It was starting, restarting, etc. OK.. but when I didn't use for some period of time the issue appears again, when I press the start button, the leds flash up by a second a nothing happen.
Making some test I discovery that disconnecting the CMOS and main battery for about 15 min, the TP starts ok ( while you need to setup the BIOS again ), but then I discovery a better solution : using the laptop with the CMOS batt always disconnected, always start !!! ( but you must to reset the BIOS each boot up ).

When I started with the issue the BIOS version was 1.06 ( IWET51WW ), and meanwhile I was trying to fix the problem I upgraded the BIOS to last version 1.13 ( IWET59WW ), without fixing the problem.

I read this forum and I saw some similar problems, sometimes the only solution was change the MOBO, as now I'm using the TP without the CMOS batt, somebody have found where is the electronic component that goes wrong and produces this issue ?

Next weekend I'll disassembly the laptop, and try to measure the different values in the power section with and without the CMOS batt, and when it starts or not.

If somebody has found it the solution please reply me.

Thank you.

[zx600]

The only solution that I've found was to disconnect the main battery every time that I shudown the Thinkpad, then when I wish to restart, I put it on again, and always start OK, I've checked with another battery and the same happends, so it maybe something in the MOBO.
Now I've disassembly the Thinkpad and I'll try to check some components like as the Maxim power chips.
I'll appreciate if somebody can help me if has fixed this issue.

[vlyne]

The only solution that I've found was to disconnect the main battery every time that I shudown the Thinkpad, then when I wish to restart, I put it on again, and always start OK

That's a very useful observation. I'm just not clear on the potential possibilities as to what might be going on.

1) Does it start without CMOS regardless of whether the battery and/or A/C as the power source?

2) With CMOS, battery in-and-out starts, but does it start with battery out and A/C only.

3) Is the battery draining out or decaying if the laptop is not used? (Check voltage on outer terminals of battery). Is the problem the same if you use another battery or a port replicator?

[starguy]

For years I've used a A21p and never had one bit of trouble with it. About 4 months ago I was given a R32 by a friend when he bought a new ThinkPad.

Last week it started hanging up at the beginning of the POST. The IBM logo would come up with the F key menu and hang right there. If I hit F1 it would say entering BIOS but never enter.

I discovered that if I booted off the battery or pulled the battery and booted off of AC it would start just fine. But the combination of the battery in & AC connected is a no go. I flashed the BIOS with the latest but it made no difference.

This morning I did a Windows update that needed a reboot. It rebooted just fine with battery & AC. I was expecting it to hang. Go figure.

I have spent hours on the Lenovo sight trying to find and reference to this problem but came up empty. And after finding this forum I see that the problem is not limited to the R32.

[zx600]

Hi vlyne, I forgot to check the forum, but now I'll answer your questions:

1) without Cmos batt starts, while the laptop was stopped in the lasts minutes with the main batt connected or while the main batt was disconnected after shutdown. ( as you can see in my first post, the cmos batt was my first workaround, but the first time the TP started because it was a time without main and cmos batt ).

2) with the AC adapter always starts while the main batt was disconnected after shutdown, if the main batt was in the Thinkpad more than 1 hour ( I think, but really I don't know how long is necessary to stay in to stop the TP booting up ).

3) The batt has 60 % charge and about 150 cycles, but trying with another batt from a T22 that is working fine on that machine in the A20 the same happens ( I leant against the A20 battery connector the T22 battery ).

3plus) I remember that with the batt in and the adapter connected ( that charges full or maintains the charge ), the TP didn't start after 2 o 3 hours of shutdown.

After 2 months I've reassembly the A20 ( I didn't find anything wrong ), and now I'm writing with the A20, I've restarted some times and always was sucessfull, now I'll shutdown, leave the main batt in and I'll try to start again in 2 o 3 hours ( I hope the new year will arrive with some goods news !! ).

I'll send a new post with the results.

Best regards and happy new year for everybody !!!!!

PD:

As an answer for starguy, when my A20 doesn't start, it only blinks for 2 seconds the HDD and power ligth, and no more, I never get the POST screen, after removing the main batt for a while, boots ok.

[starguy]

I think I've found the reason for my R32 hanging up at POST. If I have anything plugged into the Ultrabay it will not boot, either on battery, AC, or battery/AC. But if I remove the DVD or CD-RW before starting it it boots just fine. And when I push the drive back in after Windows is running, the drive does not get recognized. All these drives are recognized when I put them in my old A21p.

My conclusion is that I have a bad Ultrabay socket. I'm going to take it apart when I get time & check it out, but I have a feeling that I will be replacing the mobo.