Russian tubes - what pin material?

[GlidingDutchman]

Gee wizz - do they use unobtanium or what?

I have two perfecly good 6C33C tubes but both of them has two pins snapped off. Booooo....

Keep DIY-er that I am I tried to reattach new makeshift pins.

Soldering does nothing
Welding nada
Spot-welding neijt

What is this super-hard material/metal?

[SY]

Probably Kovar. And possibly made too brittle...

[oshifis]

I guess the material itself is nothing special, I mean it is not different than pins of other makes (rhodium plated steel or whatewer). The problem is glass conducts the heat away, so the pins can no be heated up to 350 C in order to solder them. Try some organic acid flux. I used acetylsalicilyc acid (Aspirin tablet) on steel and black tarnished copper with success...

[wa2ise]

I've used a small file to remove some surface plating off of tube pins before they would accept solder. But that was on complete pins, not pins broken off.

[Alastair E]

I cant help with repairing the pins, But an idea I used many years ago with a picture-tube was to attach a standard pin (sewing type) to a short length of wire...

Fix wire to broken pin's connection on tube-socket...

Tread pin through the tube-socket where broken tube-pin should go and arrange a small spring to push it through and maintain pressure...

Fit tube to socket, and line up pin into the broken 'stump'

This worked well for a number of years.

Issue with doing this on the 6C33c would be the heat and the current flow through the pin....
Might be OK if the broken pin is the grid connection that has only Very low currents. Doubt if it would work for long on a heater-pin though!

[GlidingDutchman]

Originally posted by Alastair E
I cant help with repairing the pins, But an idea I used many years ago with a picture-tube was to attach a standard pin (sewing type) to a short length of wire...

Fix wire to broken pin's connection on tube-socket...

Tread pin through the tube-socket where broken tube-pin should go and arrange a small spring to push it through and maintain pressure...

Fit tube to socket, and line up pin into the broken 'stump'

This worked well for a number of years.

Issue with doing this on the 6C33c would be the heat and the current flow through the pin....
Might be OK if the broken pin is the grid connection that has only Very low currents. Doubt if it would work for long on a heater-pin though!

Al, you gave me an idea there...

No heater pins are broken - grid and plate pins yes.

What if one can use the fact that the plate connection can cause the pin to heat and fuse to the stump? Like a short or something?

D

[analog_sa]

Isn't life too short to salvage cheap tubes? Think for a second how the grid pin breaks open during operation and takes the output transformer on the trip to tube heaven.

[GlidingDutchman]

Originally posted by analog_sa
Isn't life too short to salvage cheap tubes? Think for a second how the grid pin breaks open during operation and takes the output transformer on the trip to tube heaven.

You've got mail...

D

[Alastair E]

Originally posted by GlidingDutchman


Al, you gave me an idea there...

No heater pins are broken - grid and plate pins yes.

What if one can use the fact that the plate connection can cause the pin to heat and fuse to the stump? Like a short or something?

D

Now there's a thought....

Mad-cap idea two...

Set up the tube such that you have minus say, 90V on the grid.

Plate supply of 100V, with a fair current capability, say, 2A...

'Pin' set up on the pate connection...

Pulse the grid to zero or even positive for just an instant, (maybe by electronic and repeatable means) causing the tube to pass several amps...

The high current passed could 'spot-weld' the pin into the stump...