Mysterious component on the flex cable

[Rossano]

Hi,
on my X61 didn't work ThinkLight. I've found out, that the old flex cable was broken in the place, where is ThinkLight flex. Fortunately, I've had a replacement part - used flex cable. So I've used that. Result: ThinkLight works, but:

- All LEDs on the inverter are broken (except wireless LEDs, so WiFi+BT+WWAN works fine... strange).
- Closing the lid leads in no action (standby isn't activated after closing the lid, the backlight on screen is still on).

I compared both flex cables and look! There is missing some part on the replacement flex! Below are 2 photos of first flex. On the first photo, there is orange circle on that part, which is missing on the replacement flex. On the second photo is detail of that mysterious part.


This part is normally placed in plastic clips between the lower edge of the lid and the notebook chassis. It does not belong to any connector.

Is it possible that I have something during assembly / disassembly of the laptop screwed up (it would be the first time in 7 years servicing ThinkPads), or the mysterious part has to do with the diodes and detection of closing lid? Or is the replacement flex damaged regarding diodes? Does anyone know? If the mysterious component has its place, I'm immediately going to revert to old flex (with broken ThinkLight).

[rkawakami]

My guess* would be that the mysterious part is the Hall Effect sensor. That piece detects the presence (or absence) of a magnetic field. This replaces the old mechanical switch used in earlier Thinkpads.

* I say it's a guess as I haven't taken apart any of my X6x systems, but based upon your description of the system not detecting the lid being closed, that is the component that is used to determine if the lid is opened or closed.

[Rossano]

That must be it! I remember the pin present on the old ThinkPads T4x, which controls the standby mode. In vain I searched this pin on successor T60. Thank you rkawakami, you helped me.

And... what about the LEDs? Is the flex defective there? I guess it is, because of missing Hall Effect sensor. Not worth buying a new one.

[rkawakami]

Not sure about the LEDs but I doubt that it would have to do directly with the missing Hall Effect sensor. The flex (ribbon) cable could be damaged OR there may be another problem; the connector is not seated properly on the motherboard, motherboard may not provide correct voltage for LEDs, etc.

[axur-delmeria]

A while back, I damaged the flex cable on my cousin's X60 (ripped out the Hall effect sensor) when I replaced the LCD panel. The indicator LEDs stopped working after that.

[RealBlackStuff]

The Thinklight uses only 2 wires (+ and -).
Look at the ribbon side where you see the two straight "tracks".
Find the place where it's broken.
On either side of the 'break', gently scratch the brown protective film off the tracks.
Then solder (not too hot) some small pieces of wire to 'bridge' the break, making sure that you don't solder + and - together.
After testing that it works again, put a piece of scotch-tape or electrician's tape over it and put the cable back in.
Takes only about 10 minutes if you have the cable out.

[Rossano]

It's so easy? I didn't know that. Thank you for advice... but... I can't perform that in my case. When I was removing the ThinkLight, I've done it a bit roughly - I cracked the transistor below the ThinkLight (I've removed the old flex in the conviction that it won't be needed anymore). IMHO, I damaged by pliers the ThinkLight as well, because the adhesive under it makes ThinkLight pretty steady on the lid.

But I'm not worried about that. I'm about to sell my X61 and I've just ordered an USB LED light as a compensation. It's much more effective than the ThinkLight.

[RealBlackStuff]

Find any old LCD cable from any thinkpad, they all include a Thinklight.
Cut that off and solder it to your X60 'broken' cable. Still only 10 minutes...

[Rossano]

Well, I still have a replacement flex (without hall efect sensor) - the ThinkLight here is OK! But RealBlackStuff, what are you talking about? Cutting ThinkLight off and soldering it to original flex? I don't think I'm a butter-finger... but nor a precise surgeon! I can't imagine, how I could solder something, which looks like a very thin belt. I can cut the ThinkLight's flex by scissors, but how I could put together both endings of TL flex? And how about the quality of splice? IMHO, there is risk of disconnection by the time. Is there any guide? I have only one try for that...