Repairing a damage CRT/tube base

[bandersen]

What do you guys use to secure a loose tube base ? I've used super glue in the past, but it doesn't seem to hold up well to heat. I did a little research and found an old phenyl glue recipe.

I wonder if Weldwood Plastic Resin would work

[bandersen]

Here are some pictures of a CRT base I'm in the process of repairing. After removing the old base, I plan on attaching fine wires to the tips of the leads. Then, I'll thread them through the new base. I won't do that until I figure out the best glue to use though.

Here's the donor CRT base.

[Findm-Keepm]

CRT gone to air, or are you out of CRT brighteners to use for bases?

As for glue, we always used DOW RTV3145 - gray silicone that is quite firm when it cures, and will allow things to shift when the temps cause expansion and contraction. The Navy uses RTV3145 on their Heads-Up Display CRTs. Good enough for A-7 Corsairs and F/A-18 Hornets, good enough for mid-20th century consumer electronics use.

Downside: Pricey.

Cheers,

[bandersen]

Originally Posted by Findm-Keepm

CRT gone to air, or are you out of CRT brighteners to use for bases?

Thanks for the tips. This was an oddball Westinghouse CRT I picked up from American Science and Surplus back in the mid 80's. It's a dud and I have no idea what it may have been used for.

[danrulz98]

Would epoxy putty work?

What's the original glue made from?

[bandersen]

Maybe. I concerned about the long term stability with high temps. Here is RCA's old recipe from my earlier link. I don't think I'll find this in my local hardware store

This recipe for RCA's basing cement, yielding about 200 pounds of material, was "standard for all bases."

Coarse marble flour 170 lb.
Orange flake shellac 19-1/2 lb.
Durite phenolic resin LR275-2 7-1/2 lb.
Medium-color (grade G) rosin 3-1/4 lb.
Denatured alcohol 9 liters
Malachite Green aniline dye 10 g.

[danrulz98]

According to the Milliput website, their product stands up to 130 degrees C.

I can swing by the hardware store tomorrow and check out what the more generic stuff stands up to.

[bandersen]

Originally Posted by danrulz98

According to the Milliput website, their product stands up to 130 degrees C.

I can swing by the hardware store tomorrow and check out what the more generic stuff stands up to.

Hmm. I do know that a 6V6 I used super glue on broke down after a few days. That tube ran pretty darn hot. Over 130C I bet.

Anyone know the nominal operating temp of a CRT base of this type ?

[Findm-Keepm]

130 degrees Centigrade is way more than the neck would ever experience. That's beyond the boiling point of water. I've used an IR thermometer (with tungsten filter to reduce the effects of the filaments temp) on CRT necks and found the temps to be about 140 - 180 degrees 60-84 degrees Celcius (~140 - 180 degrees Fahrenheit). That's probably why the Military used RTV rubber - withstands up to 225 degrees Celcius.

Cheers,

[miniman82]

Originally Posted by Findm-Keepm

The Navy uses RTV3145 on their Heads-Up Display CRTs. Good enough for A-7 Corsairs and F/A-18 Hornets, good enough for mid-20th century consumer electronics use.

But they also farm out EVERYTHING ot the lowest bidder. Anyone who's ever had the (dis)pleasure of working on the F/A=18E/F anti-skid braking system will tell you what a POS it is, so I'm not inclined to believe Military technology is necessarily the best out there after what I've seen. That said, I do like RTV for a job like this. I've personally had good luck with Wacky Glue, the base of the CRT in my Halolight is still stuck on prett hard.

[jeyurkon]

I was tempted to mix up the base recipe also. Finding the Durite Phenolic resin turned out to be too difficult.

Scotty says he uses a silicone RTV.

It works. But, it makes me just a little nervous when I plug on the socket. It tends to flex which must put a little stress on the leads.

If you use a one part RTV try to find one that doesn't make acetic acid during the cure.

John

[bandersen]

Thanks for the tips. I'll swing by Menards tomorrow and see what they have.

[marty59]

Speaking of silicone, I've used Permatex Windshield Sealer for a varety of things. It doesn't give off that stinky acidic smell but it is quite flowable so do allow it time to cure. It's also clear. I've used it on flybacks with good results.

It will harden up better than regular RTV, kinda' like a hot glue stick does when dry. You can pour some out on a piece of paper or whatever, let it cure overnight and see if you like the results before using it on your socket.

[bandersen]

"Temperature range -80°F to 450°F" - that aught to do it

[bgadow]

Someone once suggested furnace cement, but I've never tried it myself.