Bringing a Dim CRT back to life

[Robert D.]

I have a CRT thats displays a dim picture. One response to this problem
was to run a power supply on the filament at 10 to 12 volts for 1/2 hour.
This would clean the cathode surface. Do I need a special power supply ?
As the resistance of the filament shall be very little... in effect
almost looking like a short. How much currect flows through the filament
?

[John Khalaf]

**********
I know that you don't own one of these, and neither do I, but I have
borrowed a device called a CRT rejuvenator, which pokes the cathode and
grids in the CRT with high voltage for a fraction of a second. It
allegedly reduces the life of the tube, but also restores color and
brightness. Give it a "shot". You can probably borrow one from a TV
repair joint. Good luck.
John

[carneyke]

Filaments generally are 6.3 Vac at about 1 amp. We did the 10 -12 volts on
several Mitsubishi monitors. It did brighten them up significantly. Have the
monitor disconnected from the AC line, disconnect the CRT board.
Then connect the power supply across the filament.
Set the supply to the filament voltage (6.3 Volts in most cases).
Increase the supply voltage every few minutes a volt.
We were able to bring the Mitsubishi CRTs up to 12 volts for a half hour.
Be very careful because the filament can open. If the CRT is that bad,
what difference does it make !!!! Regards, Kevin.........

P.S. Did you check screen voltage, RGB background and drive Adjustments ?
Some monitors have internal brightness, contrast controls....

< Standard Disclaimers Apply >

[Mister M.]

John Khalaf wrote:
>
> Robert D. wrote:
> >
> > I have a CRT thats displays a dim picture. One response to this problem
> > was to run a power supply on the filament at 10 to 12 volts for 1/2 hour.
> > This would clean the cathode surface. Do I need a special power supply ?
> > As the resistance of the filament shall be very little... in effect
> > almost looking like a short. How much currect flows through the filament
> > ?
> **********
> I know that you don't own one of these, and neither do I, but I have
> borrowed a device called a CRT rejuvenator, which pokes the cathode and
> grids in the CRT with high voltage for a fraction of a second. It
> allegedly reduces the life of the tube, but also restores color and
> brightness. Give it a "shot". You can probably borrow one from a TV
> repair joint. Good luck.
> John

There use to be such a thing called "Brightner" SOLD at your local TV
shop. But things have changed since then. You might jot down the number
of your CRT (The number thats on your picture tube) and call a
Electronic Distributor and ask if they make such a thing today. I
personally would replace the picture tube with a rebuilt or if over
7years old scrape it and buy a new one.
Hope this will help.

[Sam Goldwasser]

In article <324075...@canuck.com> "Robert D." <tma...@canuck.com> writes:

> I have a CRT thats displays a dim picture. One response to this problem
> was to run a power supply on the filament at 10 to 12 volts for 1/2 hour.
> This would clean the cathode surface. Do I need a special power supply ?
> As the resistance of the filament shall be very little... in effect
> almost looking like a short. How much currect flows through the filament
> ?

Caution: you could easily blow the filaments by running the voltage too
high. Then you have a big glass bottle....:-(

--- sam

[LITHOS2]

While in college I worked part time for a TV repair shop that used one of these.
From what I saw it worked great on old monochrome TV's, but it seldom worked
on color sets. It would rejuvenate one color more than another and thus the
picture quality usually got worse instead of better...

Bruce

[Robert Blackshaw]

LITHOS2@ wrote:

>Bruce

Would be a nice idea to copy the original post, just so we all know
what is being discussed.

If this is in reference to those CRT boosters that work with flyback
powered CRT heaters, I beg to disagree. I've bought several (from MCM)
and used them on EGA monitors that were dimming out. We got between
6 months to a year of "extra" use from the monitors.

Ciao;

Bob

Opinions expressed are those of the author.
Computers and Laser Printers recycled,
for fun and for profit.

[LITHOS2]

This news group isn't so active that one couldn't track a subject line. I was hoping
to save bandwidth and readers time by deleting the previous information, since
I had left the original subject line.

Also from the previous responsiveness of the "inteligent" people on this forum
I didn't feel their was a need to reiterate for the person asking about repairing
his TV. And from my post it was extremely evident that I was refering to
rejuvinating TV picture tube not computer monitors.

And I'm not Italian

Thanx