Thinkpads Forum

Hi, sorry if this should go in the other thread, but I felt it was different enough th warrant its own thread...

As you've probably seen from my other thread, I have an X200 motherboard (P8600) that does not charge batteries. Everything else works fine with it so I would like to attempt to repair it if at all possible. In power manager the battery is detected and the system runs fine off of battery but when charging the current reading shows somewhere from 0 - 0.05A, and the charging time disappears. I believe that since everything else seems to be in order, a blown fuse is a likely culprit? Does anyone happen to have a diagram or know what/where I should be looking on the motherboard to test? I have access to a multimeter (and soldering equipment so diagnosing failiure and attaching the new fuse should not be a problem), but am not sure where to begin with he search. I have had a look on the motherboard and found a large-ish square 10A fuse by the battery terminals. Is this likely to be what I'm looking for?

Many thanks for any help,
James

If the large, white ceramic 10A fuse has F8 near it on the motherboard, then that's the main fuse for the battery. If that one is blown you would not be able to operate off the battery, in addition to not being able to charge it. My guess is that there's something in the charging circuitry that's AWOL. A particularly common issue with the T23 was that an inductor would loosen (or fall off). That's one thing that could impede charging. Another thing would be a blown MOSFET. The ADP3808A chip handles the charging duties. I'm not sure where it is on the X200 but it should be near the battery terminals.

Thanks for the info, how would one go about diagnosing/repairing such things, if it is indeed possible, or is the board basically useless?

I'd say the first step would be to do a thorough visual inspection of the motherboard. Begin with the top surface and look at every component within an inch or two of the battery connector. Usually the battery charging controller chip and associated circuitry is located there (based on past inspections of the various Thinkpads I've taken apart). If you see anything that looks like it has a hole in the top, then you've found the problem . If something as small as a chip resistor or capacitor has fallen off, then it's very hard to figure out where it came from. If it's a matter of a loose inductor, then gently prying up or wiggling the part should tell you if it needs to be re-soldered.

For any damaged component the problem could be in identifying exactly what is was and then sourcing a replacement part for a reasonable price. For something like a chip resistor or inductor, it's fairly easy to solder it back onto the board. If you are dealing with something that has four or more "legs", then it becomes a little bit harder. For the MOSFETs they are generally in 8 pin DIPs (dual in-line package). The usual method in dealing with those is to cut off the legs at the side of the package and then remove each leg from the board using a solder sucker. Clean up the pads with solder wick and then deposit the replacement part on the board. This requires steady hands, good eyesight and a sharp, low-wattage (or temperature controlled) soldering iron.

I have an X201 that experienced similar symptoms and it was the battery connections. Some of these cheaper batteries can have poor quality control IMO.
The tolerances for the connections are very small. Also one needs to be careful if they use a laptop without a battery that they don't bend pins.
It may not be related to your situation but it is worth keeping in mind.

Good luck

I'm pretty sure it isn't the batteries, as It does this with the standard lenovo 6-cell, and both 9-cells I own, which also work fine on an x201 I have spare.

rkawakami, I've had a look at every component around that section of the motherboard (and quite far beyond it) on both sides, and can't seem to find anything that looks obviously damaged, and it doesn't look like anything has fallen off either...

I'm starting to get really confused by this now, hopefully I won't end up having to buy another board...

It certainly sounds like the problem is on the motherboard, since multiple batteries shows the same issue. If you can't locate any physical damage then the only thing I have left in my toolbox would be to use an oscilloscope or multimeter to try to pinpoint where the charging voltage is lost.

This just occurred to me; do you have an Ultrabase for your X200 systems? There's an external battery charger on the left side, which I believe is independent of the laptop's system. It's not a real solution to your problem but it should keep your batteries charged.

I don't have an ultrabase, but I suppose I could use my X201 as a sort of charging station. Not ideal, but I may have to live with it...

I'll have a look with an oscilloscope/multimeter if I can bring it into the lab one day, but not really sure what components I'd be testing... Also, as far as I can tell, the battery still appears to be getting a voltage, just no current according to power manager? That's what first lead me to suspect a blown fuse causing infinite resistance

Thank you very much for all the help you've given, really appreciate it!

Okay, then there's an external battery charger: http://support.lenovo.com/us/en/documents/ht037009

You may be able to find one cheap on eBay. At the moment, the ones available in the US are being offered at $30 (19.4GBP/26.5EUR). If you are patient, sometimes you can get a good deal.

I doubt I'll need one of those, I have a working X201 that charges batteries just fine. I guess I'll just have to remember to charge them in that before I go anywhere!