Re: Swapping CRTs

The ring assembly needs to be not only positioned
correctly front to back, but turned correctly. Also if you
haven't degaussed the tube the purity doesn't stand a
chance.

Heater voltage will be the same.

If you have a high voltage probe, use it. Should be 22,500.

You might try shorting R931. This goes from ground to
the low side of the brightness (G2/screen) pot on the
neck board. This will allow you to set the brightness
much lower.

Mark Jenison wrote:

> On Sep 8, 1:40pm, Rodger Boots wrote:
> > Subject: Re: Swapping CRTs
> > Mark Jenison wrote:
> >
> > > Hi all,
> > >
> > > Well, I was hoping that CRT pinouts were different between tubes 19VLUP22
> and
> > > 19VJTP22 because that would explain the problem I'm having, but apparently
> they
> > > are the same. Maybe there is something else I did wrong, so maybe someone
> here
> > > can catch my mistake...
> > >
> > > Anyway, last night I swapped a 19VJTP22 tube into a working G08 chassis.
> > > Unfortunately, the original G08 had an internal short and went to the
> garbage,
> > > so I was looking for a cheap solution. Fortunately, I had a parted out
> WG4600
> > > chassis laying around, so I used that tube for the experiment.
> >
> > The only non-repairable short a CRT will normally have
> > is a heater-cathode short, and these can be fixed with
> > a heater isolation transformer.
>
> I'm sorry; it wasn't a direct short, but there was internal arcing, and the
> neon bulbs were lighting. I took it to a friend who had a tube rejuvinator,
> and he declared it "dead".
>
> > > Procedure:
> > >
> > > I unsoldered the original socket on the neck board and replaced it with the
> > > WG4600 socket. There is a blue "blob" (cap? resistor?) attached via wire
> > > coming out of the socket where the anode wire attaches to it, and I'm not
> sure
> > > where the other end of the blue blob goes to (gnd? ??), so I left it
> unhooked.
> > > I think at one point I attached it to ground and it did nothing.
> >
> > Anode wire coming out of the neck board socket???
> > You mean the focus lead that goes to the focus pot?
>
> Correct, sorry.
>
> > > Anyway, I then swapped CRTs, but marked the original placement of the
> > > convergence rings, then removed it, swapped yokes, and replaced the rings
> as
> > > they were. I also swapped degaussing coil and shielding and mounted the
> tube
> > > on the chassis.
> >
> > Convergence assembly should have followed the tube
> > it was originally on. The magnets (rings) should line up
> > with the internal pole pieces of the tube. You might have
> > the rings too far forward or backward.
>
> Yes, I simply removed the original convergence rings for a second just so I
> could get the yokes swapped, and then returned it to it's original place.
>
> > > Results:
> > >
> > > I fired up the monitor and got a picture. However, the guns were
> overdriven,
> > > as you could see all the retrace lines. Adjusting gun gains and cutoffs
> was
> > > unsuccessful. Adjusting brightness was unsuccessful. Adjusting High
> Voltage
> > > was unsuccessful. Deflection seemed to be working fine.
> >
> > Turning down the G2 (screen) pot near/on the flyback
> > should bring the brightness down.
>
> There is a focus knob the the HV unit, and three pots which control the HV,
> among other things. I did exhaust all means of tuning the picture.
>
> > > Also, color was very screwed up. There appeared to be three zones of
> color:
> > > 1/3 red on the right, 1/3 blue in the middle, and 1/3 green on the left.
> As
> > > lines passed through these zones, they became the color in that zone. Very
> > > strange.
> >
> > Needs convergence, possibly. Needs purity reset,
> > definitely. Front rings set purity.
>
> I did not mess with the rings when they were reinstalled. It sounds like you
> suggest that I should.
>
> > > So initially I'd say that this doesn't work so well. I can't explain why
> it
> > > didn't work, so I thought maybe the socket was off by a pin or something
> else
> > > was screwy. Maybe the heater voltage is incorrect or something. Any
> guesses?
> > >
> > > Anyway, tonight I'm going to try swapping in an Ampliphone tube and see if
> I
> > > get better results. Maybe someone out there would be willing to swap me an
> > > Ampliphone tube for a 19VLUP22?
> >
> > Don't give up on the tube you have now. Not yet.
>
> Sorry, it's long gone.
>
> While the color could be adjusted, the fact remains that the brightness/gun
> drive levels are way too high, as I was unable to reduce or remove the retrace
> lines. Maybe the heater voltage for this tube is supposed to be different?
> I'd really like to find a way to use this tube. Maybe I'll just swap the
> Ampliphone onto my Tempest monitor and use the Tempest tube for the G08...
>
> ----------------------------------------------------------------------
> Mark Jenison E-mail address: jenison@cig.mot.com
> Cellular Infrastructure Group Motorola--Arlington Heights, IL
> ----------------------------------------------------------------------
Received on Wed Sep 8 15:40:16 1999