Re: Significantly drop G2/brightness (4600 raster hack)?

----- Original Message -----
From: "Rodger Boots" <rlboots@cedar-rapids.net>
To: <vectorlist@synthcom.com>
Sent: Monday, December 23, 2002 12:38 AM
Subject: Re: VECTOR: Significantly drop G2/brightness (4600 raster hack)?

> Gregg Woodcock wrote:
>
> >OK, here is a very interesting udpate.
> >By putting increased resistance, I was able to drop the previously lowest
> >(stock/non-modified) G2 of 375V to about 200V with not a bit of
difference
> >in brightness. Well I figured I'd show the macine who was boss so I
shorted
> >the G2 pin to ground (0V). I got a picture that was about half as bright
as
> >it should have been to be perfect. What is up with THAT? I got roughly
the
> >same brightness with it ungrounded. I am going to use the rejuvenator to
> >check for G2 short in the tube but as I recall, I backed this one up to
> >another machine that was working fine and it proved without a doubt that
the
> >tube was fine (95% sure about that). I must have some kind of a ground
> >problem but I just don't see how/where...
> >
> >
> If running G2 grounded still gives a fairly bright picture you have
> either too high high voltage or not enough cathode to grid 1 bias.

HV is definitely not too high so it must be G1 bias. What is normal range
for this?

> Since dropping G2 to ground DOES get the brightness low enough you might
> just add a second resistor from G2 to ground to whatever resistance you
> already have from G2 to the screen pot so the effective voltage range of
> the pot is where the CRT needs it. It's not going to hurt anything to
> run G2 near ground, but make sure the high voltage isn't excessive.

If it were my machine, that's probably what I'd do but this is for somebody
else and I really want it to be proper (or as proper as the raster-hack can
be)...

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Received on Sun Dec 29 09:01:44 2002