T20 power problem with a slightly different twist

[phelix]

I have a T20 that works fine when on its battery. However, as soon as the charger is plugged in it dies. It also won't power on when the charger is plugged in, with or without the battery installed. The HDD light flashes briefly, the power light shuts off for a few seconds, the floppy drive (if installed) buzzes momentarily and that's it. The charger will charge the battery just fine.

I've tried several things to fix this:

• replaced the CMOS battery
  tried a different charger
  used both of those chargers with a T41 and a T43 (can you tell I like thinkpads?) and they work fine
  taken the system apart and reseated all connectors that I could find, and reseated the processor
  put the T20 into the fridge for 2 hours
  held the power button down for 2 minutes while standing on my left leg with my right arm pointing north
  cursed

Is this the symptom of a bad system board? I searched through this forum and found posts where people are having similar problems except they all seem to have a completely dead system whereas mine at least works on its battery.

Any help would be appreciated.

F

[rkawakami]

held the power button down for 2 minutes while standing on my left leg with my right arm pointing north

LOL!

From the sounds of it I would think that your AC adapter would not charge your battery at all. Possible point of problem is in the power jack itself. A T21 I'm looking at right now seems to have the jack held in place by a screw in the bottom of the laptop. They also seem to be available on eBay:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 8738432710

Since there appears to be four wires attached to this jack, there could be a switch inside the jack which may not be working correctly. Of course, it could also just be that there are extra, parallelly connected wires for handling the current. Since you have taken the system apart and the jack relatively cheap, it may be worth it to try replacing this part before assuming the worst (the motherboard).

[phelix]

Thanks for the reply. The battery does actually charge fine. I will look closer at that socket though. The screw that holds it in place is present and doing its thing. Without it the socket flops around.

[phelix]

One other data point: if the charger is not plugged into the wall plugging it into the Thinkpad has no effect. But as soon as it's plugged into the wall the Thinkpad dies.

[rkawakami]

Ohh... that doesn't sound good... That seems to imply that whatever voltage is being supplied by the AC adapter causes the laptop's power problem. Is there any way you can verify the voltage? I know you said that you tried it with your other T4Xs but it would nice to hear it's outputting the 16V that it is supposed to provide.

[phelix]

I have access to two power supplies at the moment. The 72w supply has a no load output of 16.6v and the 54w supply has a no load output of 16.3v. Both charge up the T20, T41 and T43 batteries just fine. I know the 54w supply is under rated for any of the T series but I figured in a pinch they would be OK, particularly if the units are powered off when charging. So far the T41 and T43 are working normally; only the T20 is having trouble running off of either power supply and it's been doing this since at least April if not before.

[rkawakami]

It's sounding like there's something wrong with the power circuit on the motherboard . If the AC supply is able to recharge your battery but not operate the laptop, then that seems to be something other than a simple DC power jack. Does the laptop seem to work off of the battery for the "normal" amout of time (i.e. there isn't an excessive amount of current being drawn)?

[phelix]

The laptop runs for about 3 hours on a full charge drawing 0.8-0.9 amps.

Plugging in a Hawking Technology wireless PC card raises the power consumption to 2.2 amps; this kills the battery in 10 minutes or less. That consumption seems ridiculously high.

I can understand consumption 2.5 times higher reducing battery life to perhaps 40 minutes from 180 minutes but 10 minutes is odd. But maybe that's a different issue.

[rkawakami]

Interesting numbers... I was going to suggest earlier that you remove all of the devices (HDD, optical drive, all memory) and then try turning on with the AC adapter and see what happens. Replace one item at a time and repeat the power on. That would tend to isolate which device(s) is(are) causing problems. Was that wireless card plugged in before when you first posted this problem?

I'm almost sure that your wireless card or PCMCIA card cage is somehow defective. If you can track down the specs for the Hawking card, that should tell you what the nominal current draw would be for receive and transmit. 2.2A is way high in my opinion. Even if it draws an amp (or two!), the AC adapter is rated for 4.5A so at most it would run real warm. If there is a short somewhere then it only occurs when the AC adapter is plugged in since your battery times are okay.

BTW, how did you measure those current numbers? MobileMeter?

[christopher_wolf]

I agree with Ray here, 2.2A is a *very* high current draw when you engage the Hawking PCMCIA card. The only way I can see it taking the battery life down to 10 minutes is that the machine is undergoing very large fluctuations and the battery has to provide for that.


Never saw a T20 do that before.

[mattyprice4004]

Would it be possible that the Hawking wireless card is faulty, and has somehow caused a short by drawing that much power??

I have a cheap-and-nasty PCMCIA card in my 600E and battery life is only a few minutes worse with it installed, not down to ten minutes

[phelix]

OK, I'm back; been busy helping Mum with an international house move.

I have a 2nd T20 that I can swap some parts out with. I inherited the problematic T20 from my father; I'm not sure when the problem started. I do know that he got wireless DSL and then several weeks later I noticed the power problem. So it could well have been caused by the Hawking card.

The power consumption figures are as reported by IBM's software.

I have tried the Hawking card (albeit without drivers) in a T43 and power consumption went up by 0.1 amps or thereabouts.

I have tried the T20 in a docking station and it behaves the same way; this would tend to indicate it's not an issue with the power socket but something more fundemental.

[w!nx]

Bought new CMOS battery and AC adapter (FRU P/N:02K6757)

Have tried the Lenovo/IBM way to isolate issue, including ripping the TP down to pieces to check for burn/scorch marks.

The AC plug/port (whatever) does show some discolouration when I turned cannibal and opened it up. Used some switch/contact cleaner - still having same issues?

Anyone have a resolution to this?? I emailed Lenovo and am still awaiting a reply.

[phelix]

A new (used) system board has solved the problem. The laptop is now working happily with a Netgear WG511 wireless card.