Our FANUC 18i had a colour CRT (A61L-0001-0094) that developed a red/blue shadow on everything — text was unreadable after warm-up. Posting the fix in case someone hits the same.
Symptom: on a cold start the image was fine, but after 20–30 minutes a colour ghost appeared and got worse. That's classic CRT convergence drift — the deflection yoke or the convergence board is aging.
Two options presented themselves:
- Repair the convergence board (realign yoke, replace drift caps) — fiddly, and it would likely drift again in a year.
- Swap the CRT for an LCD panel.
Went with the LCD route. The A61L-0001-0094 is a colour unit, so the signal is analogue RGB (not the TTL monochrome type). The replacement panel needs an RGB→digital converter and the same 20-pin interface. Bonus: the LCD doesn't have convergence at all, so the ghosting problem is gone permanently, not just patched.
Worth knowing: colour CRTs run hotter than monochrome ones, so if you're still on the original tube, check the cooling fan above the display — a clogged fan accelerates the drift.
Anyone kept the colour CRT alive with a convergence repair instead? Did it hold?
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