I bought a rather old notebook computer -- a 1992-designed Siemens/Nixdorf PCD-3NCsl, which is actually a rebranded Panasonic CF-480C. That model was my first notebook long ago, I wrote my thesis on it and took it abroad for my postdoc year in Australia, so I have nostalgic feelings about it. A 386sl CPU with a TFT color display, which was a extravagant back then. (It made up for that by being quite small, an 8.4" VGA display which looks a bit lost in the notebook's lid.
)
The "new" unit I got now has apparently seen very little active use: It has a 1993 production date, and the only files I found on its hard disk were from 1994. (It was used in a bank, apparently by someone who did not appreciate computers much. Its cosmetic shape is great as a result, including an as-new carry bag.) But it has of course been sitting in storage for nearly 30 years. The unit was known to be non-working, but with some care and feeding it is largely working again now: Basically everything electrolyte or rubber-related had worn out: capacitors, batteries, drive belts, hard disk bumper.
But the TFT display is not its former self yet: The backlight is rather dim, and also pulses slightly. It is a CCFL backlight with two thin tubes, each about 20 cm long. I have already replaced the leaky electrolytics in the high-voltage supply and the logic control board; this has fixed some shadow/stripe issues the display had before, but has not done anything for the brightness.
I have not had to fix one of these yet and am unsure about a few things:
- Do CCFL tubes age and get dimmer in storage, or should that only occur during operation?
- I tried to measure the voltage across the CCFL connections with a multimeter (1 kV range, 10 MOhm/50pF input), but the voltage collapsed immediately. Is that to be expected, or is it a sign of an issue with the supply?
- Is there anything else I could measure or otherwise test to narrow down the cause? (Tubes vs. supply?)
- If the CCFL tubes should be the culprits, is there any chance of getting replacements? Were these standardized in size; should there be a voltage rating on them?
Many thanks for your advice!