yyzkevin

I ordered a VGA driver/controller board that is sold with/for the AT050TN22 v1 so I could verify how they are generating the timing and maybe learn an easier way to generate the needed voltages.

PIN37 (DCLK) is measured at 39.4042 MHz
PIN9 (DE) is measured at 33.6341 KHz
PIN8 (MODE) is pulled high
PIN10 (VS) is is measured at 37.9157 KHz but ignored by display
PIN11 (HS) is measured at 70 Hz but is ignored by display

Full length of DE pulse is around 16us (very lazy I eye-balled cursors)

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I got the AT050TN22 V.1 in the mail finally from Aliexpress. I wanted to do some testing straight away so I quickly put together an adapter board for the 30pin to 50pin. I only connected the MSB for the colours as my main immediate concern is timing.

Downside of this unit vs the WVGA unit is we need to provide the voltages to drive the tft externally VCOM, VGH(+15V),VHL(-10V),AVDD, etc. This will need to be integrated into the adapter board, along with the +10V for the backlight which ideally will be powered and controlled by the inverter supply to maintain Fn- control of the brightness/contrast (vcom a/c)

I am currently playing with a TI TPS65100 for voltages, however most likely will implement something similar using passives if I can learn enough to cobble together something.

For timing in my initial tests I seemed to need to meet a minimum pixel clock of 25MHz to get an image but this was very preliminary. I also experimented with DE modem vs HV mode. It is not the easiest as we only have access to the pins from the CT65535 that were brought out for the original CSTN display.

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For my initial attempt, I have used the WVGA (800×480) screen taken out of DTN-X680 GPS that I purchased online. Following instructions from https://garakutaen.sakura.ne.jp/index.html I created an adapter to connect the 30pin flat flex of the PC110 to the 40pin flat flex of the X680 display. I then used the CT65535 program from above to update the registers to switch over to the LCD. Generally it works, however I did not spend too much time on this yet as I want to more closely explore a closer matched screen I found (AT050TN22V1). There is a flickering which is not acceptable, I believe this is strictly related to the parameters used for timing / signal output on the ct65535 and not the quality of my wiring and could eventually be corrected. My main issue with this screen is the fact is the wrong aspect ratio and cannot take up the full display window.

The following is a gallery is my various attempts and failures:

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The Failure:

If you are reading this page, you already know what this is about, the vinegar syndrome failure of the Citizen L6481L-FF CSTN LCD display on the IBM PC110.

Here are some of the resources I read to try and understand why the screens have failed and what attempts could be made at repair:

• https://www.youtube.com/watch?v=zbrW7uUYpkw
• https://garakutaen.sakura.ne.jp/pc110/18thmLCD.html
• https://en.wikipedia.org/wiki/Cellulose_acetate_film

Failed Repair Attempt:

I spent some time removing top layer however the second layer would not come off together so I had to spend time carefully scrapping it away.

After I had removed enough I powered the screen up and used a polarizing lense to look for any contents. I was unable to see anything and I noticed some cracks, presumably I caused this while attempting to remove the layers. In any case I called this a failure and ended it here.

I have several more of the failed screens, at a later date I may attempt again carefully removing the “rotten” layers and applying a new polorizing film. Although the tft upgrades are nice, I would like to one day have a working unit with the origional display.

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Replacement Module:

I’ve searched high and low, and there does not seem to be a drop-in compatible replacement module. There are some sites that list stock for the citizen origional module, however when I contact them to ask if it is “new old stock” i.e. they have been on a box and likely also failed, they tell me they no longer have it.

So it seems, replacement route involves installing a different display (TFT) along with an adapter. I will explore this route in other posts.