Identifying a SMD component on a T420

T400/410/420 and T500/510/520 series specific matters only
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la_vache
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Identifying a SMD component on a T420

#1 Post by la_vache » Tue Mar 21, 2017 4:52 pm

Hi everyone !

I have a T420 (and I like it) with a trackpoint failure ; a SMD component has been pulled off the board as you can see on the pictures below :

Image

Image

The problem is that I can't identify this component so I can't replace it. I searched for a similar component on used motherboards or any kind of equipment with SMD on it... no success...
Is anyone has an idea of what it is so I can try to fix it ? :idea:

Note : I can live without the trackpoint working then I won't buy a complete keyboard just for replacing this little...thing. ;)
« Fetchez la vache ! »

4uk4a
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Re: Identifying a SMD component on a T420

#2 Post by 4uk4a » Tue Mar 21, 2017 7:39 pm

Hi

In fact you do not want to know :)

First you need to find out the name of the microcontroller - see image :
https://geekhack.org/index.php?action=d ... 3229;image

If this name is TPM754A, see page 9 :
http://pdf.datasheetcatalog.com/datashe ... PM754A.pdf

Maybe you will smile fortune, and it will be just a resistor

Good luck

thinkpadcollection
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Re: Identifying a SMD component on a T420

#3 Post by thinkpadcollection » Tue Mar 21, 2017 8:48 pm

Measure the SMD length and width and this will be your dimensions in 4 digits in mm, also they look right to be all same also I can tell they are resistors. Measure ohm with your meter on on both ends of each and see if all other 3 are same and get like ohmage one from any junker parts.

Cheers, thinkpadcollection

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Re: Identifying a SMD component on a T420

#4 Post by RealBlackStuff » Wed Mar 22, 2017 6:36 am

Go to e.g. Wizz-Itech in Quimper and check with their repair/parts department if they have a spare keyboard from a T410/T420/T510/T520/X220/W510/W520, they are all usable.
Look at the color of the small "cups" under the individual keys: manufacturer NMB=red, ALPS=white, Chicony=grey

PS: as for your signature: holy cow! :mrgreen:
Lovely day for a Guinness! (The Real Black Stuff)

Check out The Boardroom for Parts, Mods and Other Services.

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Re: Identifying a SMD component on a T420

#5 Post by rkawakami » Thu Mar 23, 2017 1:12 am

RealBlackStuff wrote:PS: as for your signature: holy cow! :mrgreen:
Nice reference! I had that scene from the movie as my desktop background on a T23 many years ago.
Ray Kawakami
X22 X24 X31 X41 X41T X60 X60s X61 X61s X200 X200s X300 X301 Z60m Z61t Z61p 560 560Z 600 600E 600X T21 T22 T23 T41 T60p T410 T420 T520 W500 W520 R50 A21p A22p A31 A31p
NOTE: All links to PC-Doctor software hosted by me are dead. Files removed 8/28/12 by manufacturer's demand.

la_vache
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Re: Identifying a SMD component on a T420

#6 Post by la_vache » Mon May 01, 2017 12:44 pm

Here are the infos I gathered from your advices :

1 - The micro-controller is a PTPM754DR.
I tried to get some infos from the TPM754A datasheet, but I'm not good at understanding it. I'll give it an another try.

2 - SMDs are 1x2mm sized.
From left to right I measured : [the_missing_one] - [809 ohms] - [825 ohms] - [875 ohms]
Not exactly what I expected...but they seem close anyway.

3 - Keyboard "cups" are transparent white. I keep searching for spare parts... ;)

I'm now going to cross the bridge of Death. If I see something, I'll tell you guys.
« Fetchez la vache ! »

4uk4a
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Location: Riga, Latvia

Re: Identifying a SMD component on a T420

#7 Post by 4uk4a » Mon May 01, 2017 4:04 pm

sample

Image

I think- the resistance should be the same
To know exactly, it is necessary to cut the conductive paths.

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