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WTB: Screen for Compaq Portable 486c - 640X480 10.4" TFT LCD (COLOR) p/n 128902-001

creepingnet

creepingnet

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WTB: Screen for Compaq Portable 486c - 640X480 10.4" TFT LCD (COLOR) p/n 128902-001

Hello, just inquiring if anyone has a parts cache for Compaq/HP and if they have this older part for a Compaq Portable 486c (color) luggable "lunchbox" PC I'm repairing.

The screen I'm looking for is a 10.4" 640X480 TFT color LCD panel. the original is cracked and the trim-pots on the side are busted up. The Part Number is 128902-001.

Or possibly a DOA Compaq Portable 486c unit for parts with a good screen?
 
I don't know how the internals of that computer look, but if you can get a VGA signal out of it somewhere, you might be able to cannibalize a 10.4" LCD monitor and bodge it in that unit.

Ebay has some 10.4" monitors for under $100, but I'm not sure how much you're willing to spend.
 
Mad-Mike said:
Hello, just inquiring if anyone has a parts cache for Compaq/HP and if they have this older part for a Compaq Portable 486c (color) luggable "lunchbox" PC I'm repairing.

The screen I'm looking for is a 10.4" 640X480 TFT color LCD panel. the original is cracked and the trim-pots on the side are busted up. The Part Number is 128902-001.

Or possibly a DOA Compaq Portable 486c unit for parts with a good screen?
Click to expand...


I was collecting them in the early 00's, and have about a dozen of them that I started to go through yesterday.
They don't seem to have survived very well. So far, I have two working power supplies and one completely working color screen
out of eight.
The flex print cable to the video cards have all gone flakey, one is going again after cleaning.
Most of the Conner drives are dead. They used a small three pin connector for power, will be trying to replace with a CF later today.

Also, one of the panels has a Sharp part number on it: LR76993
 
Al Kossow said:
I was collecting them in the early 00's, and have about a dozen of them that I started to go through yesterday.
They don't seem to have survived very well. So far, I have two working power supplies and one completely working color screen
out of eight.
The flex print cable to the video cards have all gone flakey, one is going again after cleaning.
Most of the Conner drives are dead. They used a small three pin connector for power, will be trying to replace with a CF later today.

Also, one of the panels has a Sharp part number on it: LR76993
Click to expand...


It isn't looking good for finding a correctly working screen. I only have one out of all of mine that has one with decent contrast, or doesn't have noisy video.

Today's project was getting a 2gb disk-on-module installed. It may be that logical block addressing only works on the 486/66 models (1992 mb revision)
Have to check the prom revision, or if a later version of the configuration utility is needed than 2.22C that I was using. There was only one of mine that had
a >1gb disk inside, and that was a 486/66 unit. It turns out IBM H3342 ST-3660A and IBM DJAA-31270 drives have the 3 pin power connectors they use.
There was one ST-3660A drives installed in a unit, all of the rest are Connors.

486/66 models added a fan to the underside where the hd and floppy are, so I canabalized that to get the 3 pin connector for power, then made a 3 pin to
AMP 4 pin jumper cable for the DOM. You also need a male-male 40 pin ribbon cable to go between the DOM and the flex cable that plugged onto the original
IDE drive. On the 486, if you run the config utility, it asks for a config module not on the disk (!ISAC01.CFG) while it doesn't ask for that on the 486/66. Need
to see if finding that makes LBA disks work on the original 486C.
 
Last edited:
Al Kossow said:
It isn't looking good for finding a correctly working screen. I only have one out of all of mine that has one with decent contrast, or doesn't have noisy video.

Today's project was getting a 2gb disk-on-module installed. It may be that logical block addressing only works on the 486/66 models (1992 mb revision)
Have to check the prom revision, or if a later version of the configuration utility is needed than 2.22C that I was using. There was only one of mine that had
a >1gb disk inside, and that was a 486/66 unit. It turns out IBM H3342 ST-3660A and IBM DJAA-31270 drives have the 3 pin power connectors they use.
There was one ST-3660A drives installed in a unit, all of the rest are Connors.

486/66 models added a fan to the underside where the hd and floppy are, so I canabalized that to get the 3 pin connector for power, then made a 3 pin to
AMP 4 pin jumper cable for the DOM. You also need a male-male 40 pin ribbon cable to go between the DOM and the flex cable that plugged onto the original
IDE drive. On the 486, if you run the config utility, it asks for a config module not on the disk (!ISAC01.CFG) while it doesn't ask for that on the 486/66. Need
to see if finding that makes LBA disks work on the original 486C.
Click to expand...

I can confirm this, I tried stuffing a bunch of different drives I had into that machine. Looks like I'm stuck with anything 512MB or lower for it. Mine is the older 486C model with a 33MHz 486 CPU.

Kudos to the guy for getting me the Sharp part# on the screen, that looks like the same nomenclature/taxonomy/layout/whatever of the numbers used by a bunch of LCD panels on E-bay.

I took mine partially apart to see if I could just retrofit some glass in there - that would be one HELL of an undertaking as the darned thing is epoxied in there and soldered with a million little wires (probably to the thin film transistors that make up the pixels).

I wish I knew the pinout for the video connector so I could compare it to some of the E-bay screens I've looked at. It almost looks like Compaq used some kind of industry-standard Industrial machine screen in there on these computers - like a low-end model, like something you'd find on an Injection Molding machine or a Automobile OBD-1 diagnostics computer of some kind from 1991. Trying to cross reference candidates that might work. I'm no stranger to modifying connectors on stuff to repurpose them for other purposes. The dimensions of the screens on E-bay appear to be almost dead on to the Compaq (4 stepped screw connectors outside the perimeter of the screen, some of which are held in with screws that are surface level and flush).

Makes me wish I snagged the Portable 486/66 I saw on E-bay a year or so ago, it was untested, but then I probably would have had a bad screen on that one too.

A bit on the aseembly of these screens - the entire back is a thick sheet of aluminum held on by double sided tape, not like the front, but pro-grade tinfoil thick. Take it off, the plastic frame holding the backlight assembly is separate and has a Compaq part number.
 
It's a pity these are so hard to get and unreliable. Mine also has a screen that sometimes gets a couple lines through it.. used to be just fine only months ago. Annoying.
 
Remarkable..

I have the same issue with a monochrome screen of my Portable 486/66. The screen only displays vertical lines, see picture below. I can work with the system by connecting an external monitor to it, so I'm sure my graphics card is fine.

I'm still looking for a new screen, but the 486 is rare and spare parts are hard to find also..

IMG_0820.jpg


Bye the way..
For the ones that have a color screen, I know you can calibrate it very easily under the main screen panel..
 
Al Kossow said:
do you mean all of the pots along the edge? do you know what each one does?
Click to expand...

Yes, a friend of mine told me you can easily calibrate the screen by changing the pots with a cue tip.. it has to be easy.

I also have a color one as well, but It won't start up at the moment. If it works again, I'll try it myself first ok?
 
Was just checking back here on my semi-annual search for such screens, I'm wondering if the lines are possibly caused by the same kind of issue the old Game Boy had - would not hurt to try using some source of heat to re-seal the contacts between the screen and the edges of the connector. I know some people do this to their Nintendo Game Boy DMG-001 to get rid of missing lines, could be the same sort of thing.

I'm still looking for the replacement, wish I knew the connector pinout, then I could look into BenHeck-ing some sort of solution using a standard 10.4" 640X480 TFT LCD panel off of E-bay, I'm seeing a lot of SHARP LM and LQ units that almost look like they have the same screw layout as the original LR76993/128902-001 part and/or even have a similar pinout/cable situation. With some of the similarities it's got me wondering if Compaq just went with an off-the-shelf industrial screen or something else. Would be cool to compose a list of "compatible" panels for people who wish to replace.

I've since put a SoundBlaster Pro II in this thing, surprisingly, it outputs to the internal speaker somehow IIRC. I'll have to create a megathread on this unit someday as I am starting to learn more and more on it. Still trying to figure out if there's a way to trick it into using an ultra-huge hard disk as well.
 
fear025 said:
I've got one for parts or repair posted to eBay if you are still interested: http://www.ebay.com/itm/332036920654

As I mention in the auction, the screen still worked when the unit would boot up, but that was years ago.
Click to expand...

Rats, I missed that one.

Still looking for a screen and looking at alternatives. Looks like my SHARP model# was wrong, looks like it's an LQ or LM series screen of some kind with a 30 pin connector. May also be up for grabs after awhile if I can't find a screen for it - as/is for parts.
 
I have a restore process for repairing the Sharp displays used in these. I could offer my service for a fee to restore these if anyone needs. It involves several hours of careful work, but it will keep it working for years to come.
 
I should note though that I've decided these displays are just hardly worth the trouble, even at their best they are not great looking by a long shot. I'm going to be playing with finding the very nicest display I can to put in one, just for fun.
 
I wanted to go with the NL6448BC33-74 panel, which is IPS and would look amazing, but it was harder to get a controller for. I went with a AA104VH01, which is easy and cheap to get a controller with it. I managed to get the panel with all supporting parts for $100 shipped. I've already installed it and it works well, just doing the final cabling. Lining it up inside the 486c is the hardest part. I went with attaching it to the frame from the original LCD, making it easy to attach.. but lining everything up so that the outer plastic covers screen opening lined up perfectly is tricky.

Now I'm just fussing with HDD replacements.. CF is being difficult.. but the original disk is very noisy and slow, and probably will die any day.
 
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