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Replace 755CSE LCD with 755C LCD?

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clamic235
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Joined: Fri Jun 21, 2019 5:09 pm
Location: St. Louis, Missouri

Replace 755CSE LCD with 755C LCD?

#1 Post by clamic235 » Wed Jun 26, 2019 4:32 pm

I have a 755CSE with a badly damaged screen. It's barely usable, external monitors work fine though. I found a replacement screen for a 755C for only like $20 on eBay. Would it work to put a 755C screen in a 755CSE? They're both 10.4" and 640x480. The only difference I know of is the technology. 755CSE screen is DSTN, 755C screen is TFT. I know for a fact from the service manual that the LCD assembly for the 755C and CSE have different connectors to the motherboard, but I don't know if the LCD's connector to the assembly itself is the same or not. I would take apart my CSE to find out, but I don't want to break it and some components are really stuck in there (i.e. the battery) and I don't want to break them trying to take them out. Any advice, anyone? Right now I think I'm just going to have to use an external monitor for this laptop.
[References]
Manual for 755C and CSE: https://www.opweb.de/en/model.php?id=5691
Pics of my ThinkPad screen VS a 755C: https://imgur.com/gallery/elzfydr

clamic235
Posts: 3
Joined: Fri Jun 21, 2019 5:09 pm
Location: St. Louis, Missouri

Re: Replace 755CSE LCD with 755C LCD?

#2 Post by clamic235 » Mon Jul 01, 2019 12:44 am

Nevermind, I got the 755C screen and it turns out it isn't compatible and there is no possible way to make it so. Took both screens apart for nothing :roll: but at least I was able to get both of them back together without damaging them

goldeneagle
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Posts: 131
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Replace 755CSE LCD with 755C LCD?

#3 Post by goldeneagle » Tue Jul 09, 2019 5:11 pm

Strange, as they should both be compatible, at least on the connection to the motherboard riser board. I don't blame you on replacing the DSTN, as it tends to have a crappy image, especially when you can't find ANY laptops these days with a DSTN screen (and why, when TFTs are so darn cheap to produce without as many dead pixels per unit as 20+ years ago?)

I speak from some experience, as I just tore down a 755CD and 2 x 755CE this past week for motherboard/CPU replacements. And yes, the LCD connectors are indeed very fragile. They suffer from cold solder joints, so beware when pulling connectors off.

As for batteries, I highly recommend removing the standby battery (underneath the floppy, covered by the front infrared assembly). Eventually, it will leak and corrosion will hit the motherboard.
Historic ThinkPads owned:
300 (x3), more 355's than I know what to do with, 360C/CSE/CE/P, 510CS, 560/E, 600E, 701C/CS, 730TE, 750/C, 755C(x3)/CE(x3)/CX/CDV/CD, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

clamic235
Posts: 3
Joined: Fri Jun 21, 2019 5:09 pm
Location: St. Louis, Missouri

Re: Replace 755CSE LCD with 755C LCD?

#4 Post by clamic235 » Sat Jul 13, 2019 6:20 pm

goldeneagle wrote:
Tue Jul 09, 2019 5:11 pm
Strange, as they should both be compatible, at least on the connection to the motherboard riser board. I don't blame you on replacing the DSTN, as it tends to have a crappy image, especially when you can't find ANY laptops these days with a DSTN screen (and why, when TFTs are so darn cheap to produce without as many dead pixels per unit as 20+ years ago?)

I speak from some experience, as I just tore down a 755CD and 2 x 755CE this past week for motherboard/CPU replacements. And yes, the LCD connectors are indeed very fragile. They suffer from cold solder joints, so beware when pulling connectors off.

As for batteries, I highly recommend removing the standby battery (underneath the floppy, covered by the front infrared assembly). Eventually, it will leak and corrosion will hit the motherboard.
The layouts of the circuit boards surrounding the screen are different... check it out, I took them both apart: https://imgur.com/a/caXndfO I'm probably going to return the 755c screen anyway. Some of the ribbon cables surrounding the screen were broken so even if I was able to get it hooked up right to the 755CSE, I think some of the picture wouldn't display. Also, the connectors from the motherboard to the screen itself are different.

I have tried removing the main battery but it truly feels cemented in there. It is either sticky taped like the speaker grille was, or it already leaked and is stuck in there now. Also, yesterday when I went to turn the machine on, it did the memory check and then it started boot looping, on the dock and off the dock. The furthest it was able to get before restarting was to the Windows 95 loading screen. I had been playing with it and external displays just a few days ago and it didn't have that problem at all. I bet it has to do with the battery, because while the laptop is connected to power, the battery indicator LED glows a constant orange. I don't know what that means specifically, but I know it didn't do that in the past.
Edit: by standby battery, you mean the little one that's right next to the RAM, right? Hooked into the mobo with a little connector?

goldeneagle
Sophomore Member
Posts: 131
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Replace 755CSE LCD with 755C LCD?

#5 Post by goldeneagle » Mon Jul 22, 2019 6:52 pm

clamic235 wrote:
Sat Jul 13, 2019 6:20 pm

The layouts of the circuit boards surrounding the screen are different... check it out, I took them both apart: https://imgur.com/a/caXndfO I'm probably going to return the 755c screen anyway. Some of the ribbon cables surrounding the screen were broken so even if I was able to get it hooked up right to the 755CSE, I think some of the picture wouldn't display. Also, the connectors from the motherboard to the screen itself are different.
I believe you, and I just glanced at the photos. That's why I said they're the same connectors going to the riser board. If you're replacing the panel itself, then yes, the cables are all different.

I have tried removing the main battery but it truly feels cemented in there. It is either sticky taped like the speaker grille was, or it already leaked and is stuck in there now.
Nope, it's leaked. A screwdriver will mar the case (I speak from experience), so you could try using something made of hard yet unbreakable plastic to get the battery free.
Also, yesterday when I went to turn the machine on, it did the memory check and then it started boot looping, on the dock and off the dock. The furthest it was able to get before restarting was to the Windows 95 loading screen. I had been playing with it and external displays just a few days ago and it didn't have that problem at all. I bet it has to do with the battery, because while the laptop is connected to power, the battery indicator LED glows a constant orange. I don't know what that means specifically, but I know it didn't do that in the past.
Edit: by standby battery, you mean the little one that's right next to the RAM, right? Hooked into the mobo with a little connector?
The standby battery is typically blue or green. 3 NiCad cells connected together. The point is to keep the RAM powered up, so you can take your battery out with the system suspended and put in a fully charged battery. When these systems were new, these crappy standby batteries hardly even worked then, and they're notorious for leaking!
Historic ThinkPads owned:
300 (x3), more 355's than I know what to do with, 360C/CSE/CE/P, 510CS, 560/E, 600E, 701C/CS, 730TE, 750/C, 755C(x3)/CE(x3)/CX/CDV/CD, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

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