Doing MVA mod on T400 (G141C1-L01)

[toni-kfj]

Hello everyone

This is my first post here. I'm coming from the german thinkpad-forum, as I get no responses for my (somewhat outdated) questions over there
And I thought, maybe some display mod guru in here can shed some light on my questions concerning my undertaking...

So, I want to put the Chi Mei G141C1-L01 into my T400. The reason for this is that I'm planning to use it long-term, since it can run libreboot, which is important for me (fully free coreboot distribution, see http://www.libreboot.org) - and performance-wise I'm fine with it anyway

I already have the panel (G141C1-L01) and this adapter cable:
http://vnoutbuke.ru/product/perekhodnik ... in_t400_1/
It is labeled "HQ-LED40-40-141" - if you google that together with the panel name, you find something on 51nb - unfortunately, I understand nothing of this
But I'm very sure that it's for the T400 - for the T410, there was a different adapter cable.
Also I have a broken T400, I currently have to buy a new one, but this is obviously the smallest problem

Of course I compared the datasheets of a stock panel (in my case the LP141WP2-TLB1) and the G141C1-L01 before buying the parts.
Here are the datasheets:
LP141WP2-TLB1: http://www.jxlcd.com/Upload/PicFiles/LP141WP2-TLB1.pdf
G141C1-L01: http://www.display-solution.com/pdf/tft ... 100802.pdf
For the pin outs, see page 6/7 for the LG panel, and page 11 for the Chi Mei.

The cable adapter matches the connectors of the stock display cable and the G141C1-L01, also it takes into account the different connector position on the G141C1-L01 (the connector is at the top of the panel, whereas on the LP141WP2-TLB1 it is near the bottom, so the adapter cable is being the extension). Also, as you may have noticed, the adapter cable is reversing the pin order - this also matches the panel differences (LG counts right to left, Chi Mei counts left to right, from the rear view of the panel). Since the cable flips it, in the datasheets still pin 1 would be connected to pin 1, pin 2 to pin 2, and so on...
Here is a little picture on that:
https://lut.im/lHWXkW27xm/eCXBZxZOWYZJJZmt.jpg

Most of the pins seem to map corretly (the two panels have different pin outs) -- and that's my problem at the moment: _most_ of the pins do, but maybe not all, I'm unclear about that.
From the datasheets you can see that the pins for both panels are the same, except for pin 4 and 5 and pin 31-40.
Except for pin 1-5 and pin 31-40, the adapter cable connects pin number to same pin number. For pin 1-5 and 31-40, I made the following graphics, to illustrate how they are connected (you can also figure this out from the picture above):
https://lut.im/FDtqmQ6naF/PsxjRNKgrEe0G4qI.jpg
https://lut.im/onSdK0Uofd/pwpINYdGi2udE9UN.jpg

What I notice:
1) GRND is not connected to GRND on pin 1 - is that bad? I think it might work without them being connected.
2) Pin 4 (EDID power supply) on the G141C1-L01 is clearly not connected. Is EDID necessary for a panel to work properly?
3) Pin 35 and 36 on the G141C1-L01 are for backlight control - but "backlight_enable" is connected to "backlight_PWM" and vice-versa. Is that intended? This is my biggest concern. I also verified that with a DMM. Could the display still work - even though they are switched? Maybe could you also have a look at the backlight units' electrical characteristics and tell me what you think about that? It's page 6 for the Chi Mei and page 5/6 for the LG...

Other questions:
4) In the LG datasheet, there is a "BACKLIGHT CONNECTOR PIN" mentioned, see Table 4 on page 7/8. What is this? Isn't power supplied via the flex cable?

This is the corresponding (non-active) topic on the german forums: https://thinkpad-forum.de/threads/15505 ... nden/page4

I have not much experiences with display panels / electronics modding in general, so I would really appreciate any hint/suggestions/thoughts on that...

Thank you very much!
Have a nice day

LG Toni

[RealBlackStuff]

Welcome to the forum.
As described, your mod will never work, because of essential mistakes.
You need to change these:
G-pin-1 --> LG-pin-1
G-pin-4 --> LG-pin-5
G-pin-35 --> LG-pin-32
G-pin-36 --> LG-pin-31

Earlier on someone tried this panel, but never finished: http://forum.thinkpads.com/viewtopic.php?t=117815
Q1) connect them
Q2) connect them, you need EDID
Q3) correct your error (see above)
Q4) that's an internal LCD-PCB connector, not for us

With the above changes it should work.

[toni-kfj]

Thank you for your answer!!

Eww, that's bad news
Maybe it's the easiest to make a hole new cable? Because I think I have to buy some of connectors anyway - I can't solder on a 0.4mm pitch FPC...
So, how does one make such a cable?

Will I damage the display if I try to use it 1) without Pin 1 Ground and 2) with "backlight_enable" and "backlight_PWM" switched?
I think the latter will be a problem...

Can I connect Pin 1 Ground to another Ground? There are so many of it ?

Thank you


//Update: Okay, The two backlight pins can be switched either on the lenovo display cable (the pitch is maybe bigger), or on the mainboard connector, I think this is doable. As Pin 1 is at the end of the row, I might also be able to fix the Pin 1 Ground connection. Then only the EDID voltage pin is left...

[RealBlackStuff]

There are several Ground pins, so pin 1-1 is not a must.
But the backlight must be done properly.

[toni-kfj]

Again, thank you very much. You really help me with this

So, now I investigate which would be the easiest way to fix these 3 problems with the given adapter cable.

Not relying on Pin1-Pin1 to be connected is convenient, because so I don't necessarily have to strip a new connection - I can just switch the backlight pins and switch pin 4 with pin 5 on panel side, this solves the other two aforementioned problems.

And for the Ground issue, I can for example connect Pin1 to Pin31, both at the panel side. Pin31 is ground for the Backlight unit -- I hope connecting Pin1 to that is okay...

Thanks, I'll update this (it may take a while, though)

[jaspen-meyer]

https://libreboot.org/docs/hcl/gm45_lcd.html

On the T400 and T500 (maybe others), some of the higher resolution panels (e.g. 1440x900, 1680x1050, 1920x1200) fail in libreboot.

[toni-kfj]

I know that already, but thank you

If it doesn't work, I'll try to fix / patch it until it does.

[toni-kfj]

Okay, now I'm planning to build the entire adapter from scratch.
I've come too far to give up now, too much time + money invested, also I'm still interested in a T400 with an MVA panel.
Option 1: Find a company wo does it for me for $50 or less. I'll contact some tomorrow.
Option 2: Do it myself with PCB + reflow oven; connectors can be purchased in low quantity (10pcs).

My question now:

Is somebody else interested in trying to put a G141C1-L01 into his T400? I would then do some more of the adapters.
Just let me know if interest exists


Regards,

Toni

[toni-kfj]

Update: It seems that getting the adapter completely done by a company is almost impossible for under $100...

So plans again changed: I will try to fix my 3 adapter cables which I have left, so that they are fully compatible with the G141C1-L01.

Unfortunately, if there raises an interest againin this mod, one would have to purchase them again from russia / china and mod/fix them. But anyway, that interest might be close to zero So it seems then, I will be the only one in the world with a glorious MVA panel in their T400. But who cares, people already have their T480s I guess...

Anyway, I found one interesting company: http://dirtypcbs.com/

"You get: 10 copies of each board, 2 layers, any color, 100% tested, free shipping." for $14 dollar seems reasonable.
If I sometime should try to put an LED AFFS+ in my X200, maybe I'll order PCBs from there

On thursday I'll have access to a good soldering station. First time soldering @ 0.4mm pitch

[RealBlackStuff]

No need to go to Russia for a cable.
If this is long enough, it's cheaper here: http://www.iccfl.com/product_info.php?products_id=21398

[toni-kfj]

No need to go to Russia for a cable.
If this is long enough, it's cheaper here: http://www.iccfl.com/product_info.php?products_id=21398

The cable you've linked is for the T410 (LP141WP3 TLA1 compatible, not LP141WP2-TLB1). Also it's too short, it doesn't map any pins afaik (except reversing, which is a good start), and pitch is both side the same -- but the T400 cable has 0.4mm, and the G141C1-L01 needs 0.5mm, so there needs to be a pitch change. So if you start building an adapter cable with this as basis, you'd have quite more to change.

[RealBlackStuff]

Have a look at this: http://www.cables-oem.com/html_products ... ES-28.html for the G141C1.
Then find an LCD-cable that connects to the T400-mobo, which also has individual wires.
Cutting/connecting the two then should be child's play.

[toni-kfj]

Interesting idea

But I guess, no webcam/bluetooth then?

Also, to be clear: I'm fine now (hopefully) - I will just fix the few pins on my 3 adapter cables I have left. I mean these:
https://lut.im/lHWXkW27xm/eCXBZxZOWYZJJZmt.jpg

But for anybody else, the above mentioned ideas might be interesting...

Regards,

Toni

[toni-kfj]

Hey guys,

I finished the cable yesterday. Here are some pics of the final product

https://lut.im/7ZFO8HSakW/AVAkVLANX5LS8bi5.jpg
https://lut.im/nO1M8GcGpy/EHBbeU3c3vTRjyoy.jpg

Unfortunately I don't have pics of the different steps.

What I've done:
- grinded some pins open with Dremel 3000 (works w/o flexible shaft extension), used some 1mm "diamant sphere bits" (don't know word)
- tinned contacts
- prepared=tinned some 0.3 mm enamelled copper wire (next time I go for 0.15mm or so)
- soldered w/ 0.2mm tip
- epoxy glue for stretch protection, VERY important. also epoxy is heat resistant
- secured cable with kapton tape

Actually in the end it was easier than I thought, once I've figured out the right parameters (heat, how much solder, how long to solder, ...).
It was my first soldering experience though...

As I don't have a working T400 around, and being busy with other things, I'm not able to test the cabe at the moment (despite with DMM). When I have a working G141C1-L01 in my T400, I'll post pics again, of course ... but it may actually take some months...

Thank you all for your help, especially RealBlackStuff!
I might have just burned my panel otherwise

Regards,

toni-kfj

[McDonnell]

I tried and I failed on T410 a while back

I know many prefer the 16:10 format, but with the performance gain and now FHD IPS you can get with a T420 or T430, I can adapt to 16:9.

[toni-kfj]

Okay.

tl;dr
It doesn't work -- yet.

So I recently got a T400 to test my panel and adapter cable. It came with a CCFL display, so I also got an LED display cable and an LED sub card (instead of the CCFL inverter board). That's because some in the german thinkpad forums say that a LED display won't work correctly without the LED sub card.

Good thing: The backlight works, also the PWM adjustment (I have 16 different levels). Also good: no blue magic smoke
However, it does not display anything, just plain black.
So at least:
1) my adapter cable actually fits
2) I've connected it the right way (was unsure because of these really tiny connectors)
3) the pins for the backlight PWM were one of the trickiest solder parts -> my soldering connections seem to work

What I will do next:
1) flash libreboot, to make sure there is no panel whitelisting or so (there is BIOS level whitelisting of wi-fi adapters, thus I thought there might also be some for display panels)
2) compare datasheets again, especially the LVDS specs. I think the new MVA panel can draw a little more current than the old TN panel.
3) check connections of my adapter (this is not easy for me, as my multimeter tips are not fine enough for 0.4mm pitch.)

I could also:
- try with some other display cable
- try with another LED sub card (if mine is broken -- although I doubt that it's necessary for the display to work)
- try with another T400 mobo (maybe the second LVDS line is broken mobo wise, very unlikely)


If you have any (useful ) thoughts on that, feel free to share them.


@McDonnell:
Yeah, I've read the thread.
I'm trying the mod in the first place because the T400 is one of the last laptops which run libreboot (see http://www.libreboot.org).
Thus I want to pimp it to the bleeding edge


Greetings from the old continent,

toni

[jaspen-meyer]

Did you make any progress with this mod?

[toni-kfj]

Unfortunately not.

I already flashed libreboot on it some time ago, but that didn't help.

What I will definitely going to do is testing the mod with the latest coreboot, because in the meanwhile there were some patches that fix various graphics bugs, including one that supposedly fix some high res panels. (e.g. 1440x900, which the panel used in my mod also has). However, given that it does not work with the stock BIOS, I doubt that it will help much.

Also, I will definitely not go into hardware debugging, because this is too time consuming for me right now. All I will do ist test latest coreboot, and maybe play with the clock settings.
Since I'm using an X200 with an external LED IPS monitor now, I'll probably ditch my T400.

If there's some knowledged person living in the EU who is eager to work on that mod, I would send them the panel and the adapter I soldered, plus a T400 with a half broken TN screen