CurtPalme.com Home Theater Forum

**Curt Palme**

I have a mint condition green LUG tube. Problem is, the CRT socket came loose in transit (I think), rotated on the neck of the tube, and sheared off every single pin! I have all the pins, they are stuck in the CRT socket/video amp. The tube neck didn't break, but I don't have the means to tack or weld the pins back into the tube glass, if it even can be done.

The tube is useless the way it is, and I'll willing to pay $150 to someone that can do this for me.

Any takers?

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

sheared flush or is there a nub left? IF so, I would add a small external sleeve/coupler to bridge the two halves together. I once had a marquee tube with Pin 2 clipped and a small nub left behind. I repaired it easilly by using an external sleeve + solder to replacement pin, it was very solid.
Of course this was pin 2, VNB clearance might be an issue on the others?

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

wait a minute, Curt I can fix this. The White plastic cap covers a good section of pin and i've taken this off before. This would be an easy place to open up the hole in the cap and add the sleeve. Putting the sleeve under the plastic cap and clearing the VNB Thumbs Up

stefuel · Posted: Tue Aug 24, 2010 6:23 pm Post subject:

If it sheared off key and all, I think you're shnitzels out of luck. I doubt butt soldering the pins back on will hold unless like said they are sleeved.

To spot weld them back together you need a lot of current on both ends causing a short at the connection point, melting the two together. How would you get that much power to the recessed portion of the pin without passing through and destroying the gun?

Post a picture of what is left before you ship it to anyone.

stefuel · Posted: Tue Aug 24, 2010 6:32 pm Post subject:

You may wish to very closely examine the tube at the key location and make sure the glass tube in the center has not cracked allowing air to get in. No sense in fixing it if the gun is trashed before you start.

**Curt Palme** · Posted: Tue Aug 24, 2010 7:10 pm Post subject:

Sheared flush. YOu're right Chip, I should power up the filament with little wires to make sure it's OK, but it seems fine, the center nipple is fine.

stefuel · Posted: Tue Aug 24, 2010 7:38 pm Post subject:

dvh99 · Joined: 25 Dec 2009 Posts: 2158 Location: nederland

how about solder paste if you can position the pin just a fraction above where it tore of say 1/2 mm and use hot air it should make an indestructable bond make sure you use flux on the tube and pin.

wait even easier of course, first apply solder paste and the put the pin on it, it will stick, someone needs to hold the pin and the other the hot air gun.

CIR Engineering · Posted: Tue Aug 24, 2010 9:57 pm Post subject:

Wasn't there a post on this at one point a while back?

I think what whoever did was this...

The pins were hollow. So he inserted a piece of wire into the pins and then added flux as well. He then heated and applied solder where it was broken and filled the pins, with wire inside, filled the hollow pins with solder.

Might that work?

craigr

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I remember that post Craig, it was some one overseas I think.

Athanasios

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Guys!

I cut some pins off a 180DMB22 and they look to be solid.

.

stefuel · Posted: Wed Aug 25, 2010 11:08 am Post subject:

I have various (projection) tubes here and all look the same. Some type of soft solid metal. I've never tried to solder to them. I'm not even interested in trying this my self but if I were, this is what I'd do.

1. Stand the tube on it's face.
2. Put a drop of liquid flux on top of each pin location.
3. Try to form a small solder ball on top of each location making sure it's stuck to the pin.
4. Locate some stiff solid core copper wire of the same guage as the pins.
5. Cut them so they are about 4 inches long and tin one end. This gives you something to hold onto while you line it up.
6. Re-melt your solder ball and poke the tined end in centered and at the correct angle.
7. Use your Sencore CR7000 to test the tube.
8. If all is well, slide on the plastic key and epoxy well in place.
9. After the epoxy has cured, cut the new pins to the required length.

That's the best I can think of with only two cups of coffee in me Wink

Good luck

Sparky015 · Posted: Wed Aug 25, 2010 12:11 pm Post subject:

that should work, as long as the key provides some mechanical rigidity to the pins, and not the solder connection. If the mechanical rigidity is left to the solder connection itself, I imagine the connection will be short lived with a few times of removing the neck card. Worth a try though on a new tube.

RogerH · Joined: 14 Jul 2010 Posts: 64 Location: Minneapolis

If the pins are really short, soldering to them with standard melting-point solder could risk the glass/metal seal.

The pin wire is usually some material that has the same thermal coefficient as glass-probably a nickel/iron alloy, clad in solderable nickel or copper. I've heard of it called Dumet wire, although I'm not sure if CRTs use this same thing.

If the pins are sheared off you probably need to be looking for solder/flux that will bond to the core material, rather than the cladding alone.

Localized heating right near the glass could mean be trouble and cause seal deterioration or fracturing. But if you practice on some sacrificial pins on dead tubes and find the right combo of low temp solder (indium or bismuth alloy) and flux (and this may need to be a well cleaned acid flux) you may be able to do it AND have it last through the thermal cycles of being turned on an off over the years.

It also would not be wise to be using a standard 700-800 degree iron with indium/bismuth solder that melts at a much lower temp. An iron that can be adjusted only to the minimum necessary would be best.

stefuel · Posted: Wed Aug 25, 2010 1:07 pm Post subject:

"that should work, as long as the key provides some mechanical rigidity to the pins, and not the solder connection. If the mechanical rigidity is left to the solder connection itself, I imagine the connection will be short lived with a few times of removing the neck card."

That's where the epoxy comes in.

"Worth a try thouIf the pins are really short, soldering to them with standard melting-point solder could risk the glass/metal seal."

That's why I'm not interested in getting involved in it in the first place. I don't mind making suggestions though.

dvh99 · Joined: 25 Dec 2009 Posts: 2158 Location: nederland

solder paste melting point is 217 degrees c.
with bismuth a lot lower of course, 80 or 90 perhaps but is this a strong bond?
then there is laser soldering which allows very precise soldering.
i do not see hot air doing any damage.

dvh99 · Joined: 25 Dec 2009 Posts: 2158 Location: nederland

1 more thing if the pins reach the melting point of the solder with bismuth what will happen.

Sparky015 · Posted: Wed Aug 25, 2010 1:43 pm Post subject:

laser soldering is an art all into itself. I have access to a machine, but there are quite a lot of hours in just programming the machine for a circuit board, let alone a PIN on a CRT. I don't see laser soldering as a solution, or any automated soldering for that matter, it has to be done my hand ( atleast for us non-CRT manufacturing guys).

Great point on the soldering melting point, Dennis. I don't know what temperature those Pins see during use, but that should be taken into consideration in picking a solder as well. I would think Bismuth has too low a melting point for a device that seems a fair amount of heat, but I don't have raw data to confirm that.

stefuel · Posted: Wed Aug 25, 2010 2:02 pm Post subject:

I'd be worried more about the stress that was put on the pins to shear them off vs what might happen trying to re-solder them. That pin area was made red hot at the time of construction. I doubt a medium temp solder job will do more harm than has already been done. Heck, I'm surprised that the tube still is under a vacuum......or is it? Curt still has not provided a picture or the results of at tube test.