View Full Version : Removing gasket from 7JP4 on Motorola

Tony V
09-17-2016, 12:02 AM
I know this might have been discussed before but I couldn't find the topic. How and what do you use to remove the melted gasket on a 7JP4 in a Motorola VT-71?

09-17-2016, 12:34 AM
Warm water wil dissolve it. Be patient

09-17-2016, 08:03 AM
Warm water wil dissolve it. Be patient

I totally agree with Bob. Warm water, (yes!) and some patience. I have used that procedure a few times. Strange it seems but yes it works.

Maybe you could use an old dishpan or soup pot and fill it with warm water and just put the CRT face down. I know it will float, therefore the reason for a deep pan.

Just a thought...

Tom Albrecht
09-17-2016, 11:29 AM
I recall years ago thinking that various organic solvents like acetone or alchohol should be the obvious choice. But when acetone basically didn't work at all, and alcohol showed only a slight tendency to dissolve the stuff, water was the next logical choice, and worked far better. So water is indeed the answer to this question.

Tony V
09-18-2016, 01:33 AM
Thanks guy's! I will give it a try.

09-18-2016, 07:35 AM
Twice I've used a hairdryer to get most of it off and then solvent to get the rest. Fellow collectors saw it as a dangerous way to do it, but both times I didn't have any trouble. I tried water and just didn't have the patience. My way took maybe an hour.

09-18-2016, 09:32 AM
Definitely use warm water. Let it sit 10-15 minutes and most will just fall off. Use a razor blade to scrape off any stubborn pieces left. It's pretty cool when you have a nice shiny CRT when you're done!

Tom Albrecht
09-18-2016, 02:29 PM
I agree that some scraping with a razor blade or similar speeds up the process a ton. With warm water and an appropriate tool (don't knick the glass!), probably 10-15 minutes of work will do the job.

Eric H
09-18-2016, 04:38 PM
Be sure to wear some good eye/face/body protection, I hear these tubes implode far more violently than something like a 10BP4.
I've handled a lot of them with no problems, but there's always a first time.

09-18-2016, 06:01 PM
The bulb on the 7JP4 is much thinner than the 10BP4. More susceptible to impact.

09-18-2016, 10:31 PM
....probably 10-15 minutes of work will do the job.
Seriously 10-15 min?! I must have done something very wrong when I tried the water trick. It wasn't even slightly melting the residue. Seemed like it would take 10-15 days the way it was going! :)

Eric H
09-18-2016, 10:49 PM
It was very slow when I did it, you have to keep soaking it then scrubbing or scraping until it's gone. Probably depends somewhat on how petrified the gunk is.

Geoff Bourquin
09-18-2016, 11:11 PM
My experience was the same as Tom....Tried all sorts of solvents, and eventually found that warm water and a drop of detergent took it right off. I chose to chip off the petrified bits with my fingernails, but I didn't have much to scrape off.
I wonder if they used more than one material to make the gaskets...