Thinkpads Forum

I'm trying to diagnose a T61 laptop for a friend of mine. When I received it there was no video (even on the external VGA output). So upon searching google I found out about the nVidia video issue. I have replaced the motherboard which seems to have fixed the video problem (external video is now displayed) but the lcd screen on the laptop is dim. I can barely make out some windows. I now suspected the inverter or the CCFL's. I tried doing a trick which I saw someone else do in measuring the RF freq with a DMM near the inverter card. It works on a different laptop (freq is around 22kHz and is varied up and down with the brightness control. I do not get an freq output from the board on the T61. I also read where the AC output to the CCFL's appears to be around 600V's. I tried to measure this with my DMM which will measure up to 750Vac. No output again (well actually it measured 1.5Vac). I'm concerned that the new motherboard I got is not sending the proper voltage on the proper pin to the inverter board (41W1338). Does anyone know where to measure this? I assumed that I had DC input because the LED's lit on the board.

Thanks for reading.

Welcome to the forum!

Your "new" board may be bad as well. I'd try testing the laptop's LCD on another machine/planar.

Good luck.

Yes your right, I put my old board back in and viola the backlight was working again.
Looks like I need to find another replacement. Any suggestions on models? I've seen 42w7651 and 42w7875 with the CPU.

Send a PM (private message) to forum member TuuS - he usually has good, fully tested T61/p motherboards available.

^^^ X2 to above recommendation.

Thanks for the advice. I'll contact TuuS