Re-threading a CRT socket

[jpdylon]

Its a rarity that you run into, but it happens. The glue bond on the crt base socket has failed, and either the socket comes off completely, looses contact with the wires, or is loose, or a combination of all.

This is a thread to anyone who may be squeemish about performing this task and is intended to help educate those who have never performed the task.

The victim: a late 50s setchell carlson crt that does not stay lit unless you hold the socket on the crt. The socket is abviously loose by feel.

What you will need:

30 watt soldering iron
60/40 solder
solder vacuum
wire brush and or dremel tool with a wire brush attachment
some high strength, non conductive epoxy
tools to remove the tv chassis (when the cabinet is crampped)
some 28 to 30 guage wire (in the event a wire is broken)
...and alot of patience


stay tuned...more to follow

[jpdylon]

Take your soldering iron and heat up each pin one by one. when the solder starts to liquify, take the solder vacuum and suck out the solder. There's not alot, so its not a tedious task.

Once the pins are desoldered, see if you can wiggle off the socket gently. If you run into resistance, try to discover which pin is holding you back and heat it with the soldering iron to loosen the solder's grip on the pin.

This task takes time. Do not pull or yank on the socket. If a wire breakes loose at the glass, your done -- game over. Here's some pics of the base after the solder was removed, and after the socket has been removed.

[jpdylon]

Now that you have the socket off, you will see some nasty dried up looking crap. This is the old glue that has failed to keep the socket on the crt.

This will need to be chipped off, and the socket cleaned and prepped for new epoxy.

I used a small flatblade screw driver to get off the big chunks.

I then used my dremel with a wire brush attachment to get the rest of the inside of the socket base smooth.

Last of all I wiped the area down with some Isopropryol alcohol to make sure the surface was clean. This way the glue will easily adhere to the socket. Keep in mind that you will not get it perfect. There will always be some piece of crap that is still stuck to the socket -- laughing in your face.

again, more pics. First is what you can expect the old glue to look like, followed by the cleaning procedures.

[jpdylon]

Now that you've cleaned up the socket, you will want to do the same to the crt so the two will meet cleanly.

Using a wire brush (and or your fingernail) clean off any remaining glue crap that may be on the CRT nect. Some fine sandpaper works for the baked on stuff, just make sure not to scuff up the glass. Wipe everything clean with some ipa and a cloth.

I must stress here NOT TO USE HARD OBJECTS. using things like a screw driver to ship away at the junk on the crt neck is only asking for disaster. One slip can send glass flying in your face, and you looking for medical treatment as well as a new CRT to replace the one you just destoryed.

After cleaning the glass, I would recomend using some fine sandpaper (~300 grit) and gently clean off the wires. Apply light pressure to softly pinch the wire between sandpaper in your fingers (as seen in the pic.) gently pull back a few times to clean off any corrosion on the wires. DO NOT TWIST OR PUSH.

If one of the wires has broken of, carefully wrap a thin piece of 28 to 30 guage wire around the remaining existing wire, and solder it in place. You want the new wire to stick out to make the total length the same as the existing wires.

After this we are nearly ready to put the socket back on.

[jpdylon]

Now comes the tricky part. You have to slide the socket back on the CRT. To make the job slightly easier, I would use a small pushpin to verify there are no obstructions inside the socket pins. If there is an obstruction, it needs to be removed before the wires will fit through.

If you do need to remove an obstruction (like a piece of solder) you can heat up the offending pin, then use the solder vacuum to suck out the mess. If its something that is losely inside, you can use the push pin to get it out.

Once all pins are clean, its time to slide the socket back on the crt. because the inside of my cabinet was a little crampped, I had to take out the chassis. This way I could position my head behind the socket so i could see that I was properly threading the socket.

Gently align the wires to their proper pins by moving the socket aroud. once the wires are inside the pins, the socket should slip on with ease. If you run into resistance, try lightly wiggling to see if that frees the socket up. If that still does nothing, take the socket off and check again for obstruction. DO NOT FORCE THE SOCKET ON. You may bend or break the wires on the CRT neck, or slip and break the neck! Its not worth the hassle -- just be patient.

After sliding the socket on, check all the wires to see if they at least get to the opening at the end of the pins (see pic.) The solder will adhere the tips of the wires to the pins later. If one doesn't come out, extend it by using a piece of 28-30 guage wire like you were fixing a broken wire in the previous step.

After verifying that the wires meet the edges of the pins, pull the socket out just enough to get your epoxy in there. Don't saturate it, just enough so that the socket contacts the epoxy, and the epoxy contacts the glass. Apply light pressure to push the socket up against the neck of the CRT and hold it until the glue dries (ar at least becomes tacky.) I use a quick drying service cement, which works wonders for this task. After the first coat dries, i apply a second around where the socket meets the neck.

Don't solder the pins until the glue completely dries, or you will have trouble on your hands.

[jpdylon]

Now that the glue has hardened, you can resolder the pins to make your re-thread complete.

heat each pin with your soldering iron while touching the solder to the end of the pin where the wire meets. Just melt a little solder. You can blow on it to cool the pin so the plastic socket doesn't get too hot.

Repeat with each pin until everything is done. Now you've got a socket that you don't have to worry about comming loose or messing with it to get your CRT to work

[Steve McVoy]

An easier way to get the wires through the pins is to solder very thin (individual strands from a piece of stranded hookup wire) wires about 4 inches long to each lead from the CRT. Make sure the solder joint is small enough to fit into the pins. Put each wire in the appropriate pin and pull it through. When all are in place and the glue has been applied to the base, solder each pin, pulling the thin wires out as you do it.

[jpdylon]

Thanks for that tip Steve. i never throught to do that.

[polaraman]

I can't seem to get the solder to stick to the two wires. Is there a trick to this? Acid core? special flux?

polaraman

[kx250rider]

I've done it, and it's tricky. Sometimes I take some very fine (#600 or #1000) sandpaper, an clean up the wires. Be careful though, because it would be the end if you break one off at the glass. Once saded shiny, they should solder fine. Liquid or paste flux couldn't hurt, but I haven't used any in this case.

Charles

[Eric H]

This seems like a good post to make Sticky. (i.e it will stay at the top.)

[Tom_Ryan]

Originally Posted by jpdylon

Now that you've cleaned up the socket, you will want to do the same to the crt so the two will meet cleanly.

Using a wire brush (and or your fingernail) clean off any remaining glue crap that may be on the CRT nect. Some fine sandpaper works for the baked on stuff, just make sure not to scuff up the glass. Wipe everything clean with some ipa and a cloth.

I must stress here NOT TO USE HARD OBJECTS. using things like a screw driver to ship away at the junk on the crt neck is only asking for disaster. One slip can send glass flying in your face, and you looking for medical treatment as well as a new CRT to replace the one you just destoryed.

After cleaning the glass, I would recomend using some fine sandpaper (~300 grit) and gently clean off the wires. Apply light pressure to softly pinch the wire between sandpaper in your fingers (as seen in the pic.) gently pull back a few times to clean off any corrosion on the wires. DO NOT TWIST OR PUSH.

If one of the wires has broken of, carefully wrap a thin piece of 28 to 30 guage wire around the remaining existing wire, and solder it in place. You want the new wire to stick out to make the total length the same as the existing wires.

After this we are nearly ready to put the socket back on.

....woooooah doggy...just a ding dang minute!

It's also good to remember that the kovar wires that emerge from the glass base of a CRT neck are fragile and there is a good possibility that the seal on wires or even the glass nipple could be damaged.

It's tedious work to reassemble a CRT base. You've done a bang up jog describing the procedure in your threads BUT ...I highly recommend one additional life saving step. For good peace of mind apply a bit of modern technology to these tubes. It's called VacSeal.

"Vacseal® is a silicone based liquid resin system developed primarily for sealing leaks in high and UHV systems. Vacseal® will seal leaks as large as 4 micron liters per second on systems under evacuation." Ref: http://www.2spi.com/catalog/vac/vacleak.shtml

Guys 'n Gals I always used this stuff on CRTs for years and have saved many tubes from taking a one-way trip to the landfill. Small cracks are hard to see. No need to take chances. Best part is that VacSeal remains elastic and continues to flow and cure into tiny microcracks around the tube base after reassembly.

Tom


...now if only one of you guys would just take a real hard look at your junk boxes and come up with a CTC-121 CRT socket for my (not so young ...maybe possible modern) Colortack 2000. Make my day!