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760E XGA Display Distortion

Older ThinkPads.. from the 600, the 7xx, the iSeries, 300, 500, the Transnote and, of course, the 701
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kishy
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760E XGA Display Distortion

#1 Post by kishy » Mon Mar 12, 2018 11:23 am

Hello folks,
The second of my 760Es has the XGA (1024x768) screen, but has a display issue. The entire screen is "ghosted" and has somewhat of a grid overlaid on top of it.

I found that through flexing (yeah I know, bad) or applying pressure to the screen assembly, sometimes, it would appear 100% normal. I found that if I applied pressure just above the brightness slider, it would make the screen work. I took it apart and found that if I apply pressure to the ribbon cable connector on the inverter, enough pressure to cause the inverter itself to flex a fair bit, this is what did the trick and caused the screen to function normally. Sometimes, this would be a lasting effect (several minutes to an hour) and sometimes it would go back to not working immediately upon releasing pressure.

So, this implicates one of two pieces, or possibly both: the inverter, or the cable.

It occurs to me that maybe the connector just makes bad contact, but there is no real way to re-bend the contacts on these connectors to make them make better contact. I tried cleaning the contacts with a Q-tip and alcohol, but it didn't change the issue at all. It also occurs to me that the issue could be weak or broken traces within the inverter (not sure how many layers this PCB has) and therefore the inverter would need to be replaced. It's also just as likely to be a break in the cable though...

The inverter (Hitachi INVC367) can be had online for not too much money, so I may just buy one and hope that's the problem (the ribbon cable is likely to be a lot harder to find).

Unfortunately the XGA and SVGA models do not share inverters, so I'm not able to swap between them.

Does anyone have any thoughts that may help here?

Photos:
Screen images distorted:
https://i.imgur.com/u6GGOck.jpg
https://i.imgur.com/UXeFNJL.jpg
https://i.imgur.com/Qpo5kmu.jpg

Screen as it appears when holding the inverter just right:
https://i.imgur.com/o4er2BS.jpg
https://i.imgur.com/GJTljUA.jpg

The inverter itself: https://i.imgur.com/WTXZlwc.jpg
760E SVGA | 760E XGA | 600 | T21 | W520

Thinkpad4by3
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Re: 760E XGA Display Distortion

#2 Post by Thinkpad4by3 » Mon Mar 12, 2018 11:35 am

Looks like the flat flex that connects the LCD to its controller is failing. Think a replacement LCD is the only option.
Probably should be Thinkpad16by10.

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kishy
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Re: 760E XGA Display Distortion

#3 Post by kishy » Mon Mar 12, 2018 12:05 pm

Thinkpad4by3 wrote:
Mon Mar 12, 2018 11:35 am
Looks like the flat flex that connects the LCD to its controller is failing. Think a replacement LCD is the only option.
Is the ribbon cable not given its own FRU#? I find it hard to believe the panel and/or complete screen assembly is the only way to get one...

The HMM is a mess, it covers half a dozen literally a dozen models and trying to pin down what is specific to the 760E is somewhat challenging.
760E SVGA | 760E XGA | 600 | T21 | W520

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Re: 760E XGA Display Distortion

#4 Post by Thinkpad4by3 » Mon Mar 12, 2018 12:23 pm

No, the LCD unit is an FRU. All LCDs contain an irreplaceable controller with the transistors hooked up to the board using a 1024x768 ribbon cable(so like 2000 connections)
Probably should be Thinkpad16by10.

Looking For: 386 laptop, IBM or not.

kishy
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Re: 760E XGA Display Distortion

#5 Post by kishy » Mon Mar 12, 2018 12:58 pm

Thinkpad4by3 wrote:
Mon Mar 12, 2018 12:23 pm
No, the LCD unit is an FRU. All LCDs contain an irreplaceable controller with the transistors hooked up to the board using a 1024x768 ribbon cable(so like 2000 connections)
Ehhhhh...

Picked apart the HMM. It's still a mess, but now it's less of a mess.

Of all the panels listed (yikes), there are only two that are 12.1" and XGA.

Neither one of them lists a separate inverter part number, but both of them do list an "interface cable group" which apparently includes the cable and some miscellaneous bits along with it.

For "LCD Unit, 12.1 XGA (P/N 46H5735, ASM P/N 46H5731)" the "Interface Cable Group" is 46H5737.
From the Googles: "760 XD 12.1 TFT-X LCD Cable"

For "LCD Unit, 12.1 XGA (P/N 82H8486)" the "Interface Cable Group" is 82H8893.
From the Googles: "760 E/X LCD Assembly 12.1" LCD Cable"

I would have to do further research to pin down which, if either, is what's in my laptop. The diagrams are reasonably detailed though which is nice.

Both of those are showing as available to be bought, but they're also rather pricey for what the part is. I suspect I could buy a complete broken donor machine for competitive amounts, the trouble would be knowing that part was good.

As mentioned the inverter itself can be sourced online; since it isn't given an FRU number these are always going to be pulls from parted-out machines (my guess anyway).

So the question becomes, how do I verify with reasonable certainty that it is the cable and not the inverter at fault? Inverters are notoriously failure-prone items in laptops of this age, but I've never heard of one failing in this manner.

And further...if it's the cable, if the "cable" part of it (the flat flexible strip) is intact and the issue is just at the inverter connector (as it appears to be), then maybe some sort of re-flowing attempt for the soldered joints to the connector could work. On the other hand, it also might melt the cable beyond recognition.
760E SVGA | 760E XGA | 600 | T21 | W520

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Re: 760E XGA Display Distortion

#6 Post by RealBlackStuff » Mon Mar 12, 2018 2:24 pm

RBS to the rescue!
I have a complete, working 760 E/X lid with 12.1" XGA.
It also includes hinges and the LCD-cable has P/N 46H6006 / FRU 82H8486.
The rubber paint has some scratches and bald spots, but inside it looks great.
Price: $25 incl. shipping to a US address
Payment via PayPal, using option "send money to friends or family".
Lovely day for a Guinness! (The Real Black Stuff)

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Re: 760E XGA Display Distortion

#7 Post by Thinkpad4by3 » Mon Mar 12, 2018 2:28 pm

You still have that thing, wow. I guess you will finally get that thing out of your hands.
RealBlackStuff wrote:
Mon Mar 12, 2018 2:24 pm
RBS to the rescue!
:That was funny! :lol:
Probably should be Thinkpad16by10.

Looking For: 386 laptop, IBM or not.

kishy
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Re: 760E XGA Display Distortion

#8 Post by kishy » Mon Mar 12, 2018 2:31 pm

RealBlackStuff wrote:
Mon Mar 12, 2018 2:24 pm
RBS to the rescue!
I have a complete, working 760 E/X lid with 12.1" XGA.
It also includes hinges and the LCD-cable has P/N 46H6006 / FRU 82H8486.
The rubber paint has some scratches and bald spots, but inside it looks great.
Price: $25 incl. shipping to a US address
Payment via PayPal, using option "send money to friends or family".
Wow, what was the probability of that coming along? LOL. RBS to the rescue indeed.
You'll have a PM momentarily, and I do have a US address available.
760E SVGA | 760E XGA | 600 | T21 | W520

kishy
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Re: 760E XGA Display Distortion

#9 Post by kishy » Sun Mar 18, 2018 3:08 pm

I have received RBS' screen assembly, excellently packaged and in better shape than I might have expected from the description. I also received another item that accidentally included the same inverter again: a Dolch PAC 64 network analyzer, which is basically just a Pentium lunchbox PC.

As an interesting but somewhat off-topic aside: I was not previously aware that the Dolch uses an IBM 12.1" panel, P/N 46H3670 dated 97/19.

Additional markings:
BL P/N 46H3640
BL EC E16835
BL LOT No D22-C-D3U-B-4
CFL LOT No BN-A
D/N DO220220
F8550 PCB-X
46H3611 EC E16837

The inverter attached to it is a Hitachi INVC367, exactly identical to what is in my 760E. The Dolch chassis has a small adapter PCB that feeds the connectors of the inverter and panel, no flat flex cable involved. The adapter PCB then has an IDC ribbon cable that goes to the Chips & Tech PCI graphics card.

So that's cool. The panel is almost certainly identical to one found in some model of ThinkPad.

Photos of the 760E surgery will follow once I've had a chance to dig into that project.
760E SVGA | 760E XGA | 600 | T21 | W520

kishy
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Re: 760E XGA Display Distortion

#10 Post by kishy » Mon Mar 19, 2018 2:04 pm

kishy wrote:
Sun Mar 18, 2018 3:08 pm
Photos of the 760E surgery will follow once I've had a chance to dig into that project.
Phase 1 was to hook up the screen assembly as received, and verify all is working as it should.

I did find that the lid closed switch (to turn off the display, put machine to sleep, etc) is damaged/missing from the flexible cable assembly. This is not really any sort of issue, I'm still quite pleased with this purchase. My retro hardware really does not see the type of usage pattern that would benefit from that functionality anyway.

Photo of the 760E taken apart: https://i.imgur.com/SrtQVli.jpg
Photos of the newly received screen in action: https://i.imgur.com/JVxzfba.jpg, https://i.imgur.com/jnfCRAI.jpg

The next phase, now that everything has been verified to work as-received, will be to take it apart and do some parts-swapping to figure out for sure what part is faulty.

Continuing the Dolch aside: https://i.imgur.com/bXVqmLa.jpg, https://i.imgur.com/3keo115.jpg, https://i.imgur.com/EV1exyN.jpg
760E SVGA | 760E XGA | 600 | T21 | W520

Thinkpad4by3
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Re: 760E XGA Display Distortion

#11 Post by Thinkpad4by3 » Mon Mar 19, 2018 3:20 pm

I'm not australian but "Beauty!" Very nice to get that machine working again :thumbs-UP:
Probably should be Thinkpad16by10.

Looking For: 386 laptop, IBM or not.

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