Dead colour guns on crt

I have tested my 28” tube with a rejuvenator, kindly on loan from Porchy and initial tests show that the guns weren’t showing up on the needle range or with the cut off voltages slowly increased.

I rejuvenated the Red and got a small light show for 20 seconds with the neck glow going on and off etc.
Tried the green next after waiting a minute or so. It glows, but no light show and don’t seem to end the rejuvenation
Same with the blue.

I’m thinking that the guns are knackered and this time is useless?

When I reinstalled the chassis, the red was much improved, but no blue and only a very faint bit of green on the 19 in 1 test pattern.

Any thoughts?

My understanding is that the rejuvenator works by heating up the gun which makes the metal expand and the accumulated oxidisation then (hopefully) cracks off, leaving a nice clean (but thinner) gun.

I thought the same sure I have read that it burns a layer of oxidisation off of the cathode

My set has gun tracking and clean and balance short
removal ect rather than going strait for the heavy re juvinate
I've only ever used this set though so don't know what other sets offer and I'm still learning too the manual that comes with the set misses a few important bits out that I managed to get pointers on through other people's you tube videos

I've had tubes that have shown very low on the test scale
That have had to have the clean and Ballance carried out a few times to get the guns up on the scale
I can do indervidual guns on this set but it takes seconds to clean each gun I wouldent want to leave it on for longer than that if you've been leaving it on for minutes you might have cooked it
If your guns are showing nothing it's not going to hurt to keep trying it a few more times if the tubes knackered anyway
The grid voltage and heater voltage need to be set right for the tube you have though you can't just connect it and rejuvinate
Run the tube number through the tubular website to find correct voltages for your tube

As for the clean only lasting so long dosent the tube naturally build oxidisation on the cathodes through normall usage anyway so is allways degrading gradually
It's not like there on 24hrs a day in your house I would imagine it would last year's in a home environment



Edited by robotech - 15 Sep 2021 at 7:17pm

All I know is that every tube I've done so far has looked like a new tube beautiful vibrant colours ect
So they can't be all that bad

good tips on using the website tubular
and short bursts eliminating shorts
thanks robotech

i nearly picked up my first rejuvenator last week.
i will eventually get one.. and have a few tubes that i think may benefit

hope vic sorts his tube out
or at least gets it somehow verified as it’s a pain
you want to know either way if it’s a keeper
or for the scrap heap

Edited by Retroman839 - 15 Sep 2021 at 8:23pm

I have a bandk 476 it's a really nice set came from a TV repair shop and looks to have been really well looked after
It Has a selection of different sockets and all the manuals booklets and paperwork from The TV shop over the years
There's a few videos on you tube explaining how to use this model correctly without them and just the manual I would of been confused as it's not explained too well

It's a tool worth having even if the effects turn out to be short term
if your boosting a tube with 20 years plus of dayly arcade useage and it already has poor emissions to get any kind improvement over its current status is a bonus
It's not like your going to get hold of a new tube any time soon