Short, grid to cathode :Decca CS2030

[Mikey405]

Oh, that is a shame Lee. I suppose you could try building a little simple power supply to boost up the heaters a little bit and see what happens...

[Tazman1966]

Originally Posted by Hunts smoothing bomb

...I might just boost the heater volts permanently...

I'm sure that'll provide a medium term cure. Good luck fella! Look forward to the pics.

Cheers,

[Hunts smoothing bomb]

Hi Mike,

Yes, I will try and knock something up tomorrow, before I blasted the tube today I had a good picture by running the heaters at 8v.

Hi Tas, I'm sure it will work fine, just don't know how long it will last.

Cheers
Lee

[Hybrid tellies]

Hi Lee, sad to hear that it was short lived. Hopefully a replacement tube should turn up, possibly in a donar set, as most 20" ctv's of this era used the same type of tube. What type of tube is in your CS2030, Mazda, Mullard or a Japaneese type?
In the meantime you have nothing to loose by running it with a slightly boosted heater voltage

[Hunts smoothing bomb]

Originally Posted by Hybrid tellies

Hi Lee, sad to hear that it was short lived. Hopefully a replacement tube should turn up, possibly in a donar set, as most 20" ctv's of this era used the same type of tube. What type of tube is in your CS2030, Mazda, Mullard or a Japaneese type?
In the meantime you have nothing to loose by running it with a slightly boosted heater voltage

Hi there,

Not sure what tube it is as I cannot find a label any where.

I was talking to Tas on the phone earlier and he says it should be an A51-110X (I think I got that right Tas?)

Cheers

[Tazman1966]

Yes Lee. A51 110X or possibly A51 220X. I'm sure it doesn't specify what type in the manual

[Dave Moll]

The 1973-74 edition of R&TVS states that the CRT is a Toshiba E2336/4. I don't have information about equivalents.

[Steve_P]

Well if this tube is certified dead, we can do a little experiment. Up the heater volts to about twice what they should be and blast it.

Then see what happens. Sometimes it works, sometimes it does not. Tough luck if the heaters fail though.

Sometimes this bring it back from the dead. Reactivation occurs because of Cathode poisoning. Eventually there is nothing left to give, but it gave something in this case so it might be a case of severe poisoning. All reactivation does is to blast all the dirt from the cathode. Nothing more.

I do like to experiment, and I also like brutal methods as you probably notice!

Cheers,

Steve P.

[PJL]

I know nothing about tellies so this is all theory - if it fell off that quickly again does it mean the tube has air? Would it be best to run it for a while in the hope the gettering will remove the gas and then try the method used before?

[Maarten]

Originally Posted by Steve_P

Well if this tube is certified dead, we can do a little experiment. Up the heater volts to about twice what they should be and blast it.

Then see what happens. Sometimes it works, sometimes it does not. Tough luck if the heaters fail though.

Sometimes this bring it back from the dead. Reactivation occurs because of Cathode poisoning. Eventually there is nothing left to give, but it gave something in this case so it might be a case of severe poisoning. All reactivation does is to blast all the cr*p from the cathode. Nothing more.

I do like to experiment, and I also like brutal methods as you probably notice!

I have had good succes using this reactivation method with some 'older' Philips 16:9 tubes from the EWR/EWS series as used in B&O TV's. On the other hand, I tried this on a few Sony 16:9 tubes but they all went flat again after a few minutes. Even when used with a permanently raised heater voltage they would only last a few more days.

[ekcopyephilips]

Hi All

I used to use this method in the factory when we had dodgy tubes.

Disconnect all wiring going to the tube including deflection etc.
Connect all the base pins together
Blast with 30Kv for a few seconds, sometimes you see arcs, sometimes you dont.
Reconnect and try again, sometimes its a cure, other times the same fault is still there.

Mike Burton

[Maarten]

Originally Posted by ekcopyephilips

Hi All

I used to use this method in the factory when we had dodgy tubes.

Disconnect all wiring going to the tube including deflection etc.
Connect all the base pins together
Blast with 30Kv for a few seconds, sometimes you see arcs, sometimes you dont.
Reconnect and try again, sometimes its a cure, other times the same fault is still there.

Mike Burton

I think this was actually a procedure that was recommended by Philips, only if this method failed to clear the fault they would accept return under warranty. Am I right?

[ekcopyephilips]

you probably are correct, as any that went on to work were used, the others were returned to the manufacturer. All makes of tube we used seemed ok with this procedure.

[Hunts smoothing bomb]

Hello everyone,

I plucked up the courage to boost the tube a second time, this time I took Steve P's advice at double heater volts, I also left the 15w pigmy lamp on for longer and it slowly got brighter. I did this experiment on all guns and on powering up I once again have a good picture, The set has been on now after blasting for over an hour and picture is still good, fingers crossed!!

Cheers
Lee

[Hunts smoothing bomb]

Here is the result,

See pic.

(the pic on the k70 looks a bit rough cos I dont have a booster to run the signal to both sets)

Cheers
Lee

[Hybrid tellies]

Great pictures on both sets. Hope the CRT in the Decca stays up which I'me afraid only time will tell.