Missing piece in a T23

[Yattaro]

I have a T23 that will run off the battery, but not from external power. When I plug in the power cord it will start for a few seconds and then shut down, after which it won't come on again unless I remove the power cord for a second and then reattach it.

I looked inside it and have noticed what appears to be a missing resistor above the display connector, labeled C10. I have no way to replace it because I don't know its value.

I'd appreciate it if someone with a T23 could measure this resistor and tell me its value.

Also, while fixing this damage is the most obvious thing to try first, I'm not certain that this is the cause of my symptoms, so feel free to post any other insights you may of on the problem.

http://i64.photobucket.com/albums/h180/ ... _c10_2.jpg

http://i64.photobucket.com/albums/h180/ ... _c10_1.jpg

I am grateful for any help anyone can provide.

Moderator edit: Changed inline images to links; please keep pictures < 50KB and place a note in the subject line (like: *PIC*) when including images. Thanks!

[rkawakami]

Welcome to thinkpads.com!

"C10" would typically be a capacitor, not a resistor ("R10"). I'm not near any of my T23 motherboards at the moment but I will be able to measure one later tonight. If nobody has responded by then, I'll post the details (value, size, possible source to get one).

edit: You can see what it is supposed to look like from a picture I took awhile back:

http://www.rkawakami.net/ibm_t2x/let.jpg

Located at the top edge of the picture in the middle.

[Yattaro]

Makes sense, and thanks. I have a dead T21 here as well - perhaps I can take what I need from it?

[rkawakami]

Probably could but the problem would be to pick the correct capacitor. Surface mounted components like these generally do not have much in the way of markings on them which tell you what the value of the part is. Capacitors can have a code like "103", which means 10000pF or .01uF. "103" is decoded as: 10, followed by 3 zeros. If there isn't any kind of markings, then you're left with measuring it with a meter and trying to select a part that's close. In order to accurately measure a capacitor you would have to disconnect at least one end of it from the motherboard. Also, capacitors can have tolerances of 20% (or more) so some of it is educated guesswork even when you have a reading on a meter. Of course the best option would be to replace it with one from an identical board. What's the FRU of your board? It should be on a thin barcode label near the MiniPCI connector.

[Yattaro]

The FRU is 26P8218 205.

[rkawakami]

Okay, after sorting through a couple of motherboards I found a 26P8218. A quick check with my cheapo Craftsman meter says that the capacitor is 75nF (nanofarad), or 75000pF (picofarad) or 0.075uF (microfarad). As far as I know, this is not a standard value. The closest one is 0.068uF. The measured size is 0.06" x 0.03" which makes it a "0603" package, in surface mounted terminology. Taking several guesses as to the other specifications of a capacitor's parameters, this is my best recommendation for a replacement part:

Murata 0603 SMD Monolithic Ceramic Chips 0603 0.068uF at mouser.com

In case the link above does not work, go to mouser.com and plug in: 81-GRM188R71H683KA93 in the part # / keyword box. I'm going to take this motherboard to work and try to remove the capacitor and double-check my measurement with a (supposedly) more accurate capacitance meter.

[rkawakami]

Update: After removing the C10 capacitor from my 26P8218 board and using a better capacitance meter here at work, the value is 0.1uF. That would make the mouser.com link:

Murata SMD Monolithic Ceramic Chips 0603 0.1uF

The part number is 81-GRM188R71H104KA93.

[Yattaro]

Thank you very much for taking the time to do this! I'll have replace it soon and see if it solves the problem.

Thanks for taking your time to check!