Computer Monitor Cataract Repair

8 Dec 2025

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Vintage computer monitors and TVs with CRT (Cathode Ray Tubes) can experience deterioration of the layer between the CRT and the glass sheet in front. This results in visible bubbles and discoloration that damages the view.

Sometimes this can be fixed and here's how I did it on a DEC Rainbow monitor from the 1980s.

Dangers

This is a fairly dangerous project because CRT tubes are under a vacuum and they can implode. I used a face shield, long sleeves, and gloves during the process. I wouldn't suggest anyone do this.

Removing the CRT

Cataracts don't affect how the CRT works so I made sure the monitor actually works before even trying this.

There are dangerous high voltages in a CRT monitor so I removed power and let it sit for a couple days hoping any capacitor holding a charge would be drained. On some of the big caps I shorted with a screwdriver but didn't notice any discharge.

Before disassembling I took a lot of pictures from every angle so I could get it back together.

There were 2 connectors, one on the end of the CRT tube and the high voltage wire on the side of the tube.

This CRT was mounted like every other I've seen and just required inspecting to discover the various screws to remove it from the enclosure.

Safe Holding

Since the CRT has a slender neck and is delicate I used a thick bath towel in a 5 gallon bucket to hold it while working. Pressure on the neck could break it and cause an implosion. I made sure nothing was touching the neck during the process. I've never experienced an implosion but it's said to be like an explosion. There are some videos on YT showing this.

Removing the Glass

With this monitor there is the CRT tube then a glass shield glued to the front. This glue is what failed causing bubbles. The trick was to slowly separate the front sheild glass from the delicate CRT. I used a heat gun to soften the glue and pulled a thin stainless steel wire between to separate the two. I never applied a strong force to anything. The whole process took more than an hour.

Cleaning off the Glue

After the glass was removed the glue came off easy with a razor scraper. I was careful not to cut into the glass. I also used some lacquer thinner to remove some of the gunk.

Reattaching the Glass

I didn't reattach the glass because I never figured out what glue to use and didn't want to go to that effort. The monitor view is sharp and clear without it, and the front glass didn't appear to affect how it mounted in the cabinet.