T21 will not power up

[Thomcat]

I have a T21 that I purchased new several years ago. It now has a power up problem. Of course it's several months out of warranty now. Most of the time, when the power button is pressed, the HD led flashes and thats all that happens. Occasionally it will power up and work fine until the next time it is powered on.

I've tried leaving the battery out, using the battery only, using the ac adapter only, removing all drives, etc... to no avail.

Any suggestions would be appreciated.

Thomas

[JHEM]

Change the CMOS (RTC) battery!

Regards,

James

[froudeg]

Jhem

The power up issue with A21, A22, T20, T21 and T22 laptops is very common, and as pointed out before is a inherent design fault. Symptoms are the hd light flashing for a split second, the floppy drive making a noise (thats what the click noise is)...when you press the power button, but nothing else happening. It sometimes powers up if you leave it alone, and repeatively press the button, but this appears to be random and is not related to the main battery charge state, or if it's being run off the mains.

I can confirm, for this particular issue (which is the vast majority of the cases for the above laptops with those symptoms) that it is NOT the CMOS BIOS battery. It is totally unrelated to the CMOS battery, the system will always power up regardless of CMOS battery power levels - even if the battery is totally removed.

Further more your quote elsewhere,

'On modern laptops (since the days of implementation of APM) the CMOS battery does far more than simply maintain the BIOS settings. In fact it provides the current to activate the solid state solenoid that actually turns your machine on when you press the power switch. '

Is well, just plain incorrect. The cmos battery is not involved in the initial power up of any of the above laptops, the laptop should at least power up regardless of the cmos battery state...it wont complete the POST tho, but it will always power up. The power for the power button monitoring circuitry is actually obtained from the main battery/external power source.

Please stop wrongly suggesting to people that they should replace the CMOS battery - with the above exact symptoms it will have no effect what soever and is just a waste of time and money. Some people have been fooled into thinking it was the battery, but soon find out the laptop is back to its old tricks with it just powering up when it wants to.

I've got the same problem on my A21m, im an electronic engineer by trade and will take a good look at the switching power regulator section shortly - more likely than not, some overcurrent cutout is kicking in on the regulator circuitry - for what ever reason. I hopefully will get to the bottom of this mystery thats plagued 1000's of thinkpads..

[JHEM]

Froudeg,

Initially, I wasn't going to dignify your assertions with a response. But my ire got the better of me.

First, there's no floppy drive in the T series equation to "click", it's the HARD drive that is responsible for the noise.

Second, the CMOS battery plays the role I've outlined, and you quoted, and that's precisely the role as it was explained to me by IBM many years ago.

Third, I and many of the other "old hands" in these forums, the Thinkpad mail list, the NGs, etc., etc., can give you HUNDREDS of instances where the replacement of a spent CMOS battery has completely rejuvenated a dead or dying Thinkpad going back to the days of the 755 series, so I won't bother you with my uncorroborated tales of the number of Thinkpads I resucitate weekly.

(I will mention only in passing the 67 completely dead and unresponsive Compaq LT model laptops that were donated to the organization I work with, ALL of which were restored by your's truly simply replacing the CMOS battery.)

Do some models of Thinkpads have inherent motherboard problems? Apparently so.

Can some laptops be rejuvenated by simply replacing the CMOS battery? Demonstrably the answer is yes!

Is replacing the CMOS battery a proper initial step when diagnosing a fail to start problem? Well, DUH!!

Your theory is intriquing. Write back when it's proven.

Regards,

James

[egibbs]

Jhem

The power up issue with A21, A22, T20, T21 and T22 laptops is very common, and as pointed out before is a inherent design fault.

...snip...

I've got the same problem on my A21m, im an electronic engineer by trade and will take a good look at the switching power regulator section shortly - more likely than not, some overcurrent cutout is kicking in on the regulator circuitry - for what ever reason.

I'm a T20 owner and I'm not an engineer, but I play one at work.

I've never encountered this particular problem on my T20 (knocking wood). But I do find it surprising that an engineer would state that there is an inherent design fault when they admittedly don't know what the problem is yet.

All of the engineers I know and work with are extremely data driven people, and they are usually reluctant to even concede that there is a problem until they can reproduce the failure mode at will.

Reminds me of the story about the mechanical engineer, the systems engineer, and the software engineer who are barrellng down a winding mountain road in a car with no brakes. After almost going over the edge of the road and down the cliff several times they finally manage to get the car stopped, and they get out to look at it.

The mechanical engineer says "Here's the problem - the brake fluid reservoir is empty. There must be a leak."

The systems engineer says "I'm not sure - I think we should call the manufacturer and get their oipinion."

The software engineer says "Let's all get back in and see if it does it again."

Ed Gibbs