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

----- Original Message -----
From: "Rodger Boots" <rlboots@cedar-rapids.net>
To: <vectorlist@synthcom.com>
Sent: Wednesday, November 13, 2002 2:53 AM
Subject: Re: VECTOR: Significantly drop G2/brightness (4600 raster hack)?
> Gregg Woodcock wrote:
> >----- Original Message -----
> >From: "Rodger Boots" <rlboots@cedar-rapids.net>
> >To: <vectorlist@synthcom.com>
> >Sent: Thursday, November 07, 2002 12:55 AM
> >Subject: Re: VECTOR: Significantly drop G2/brightness (4600 raster hack)?
> >>Gregg Woodcock wrote:
> >>>The first raster hack I did was NO PROBLEMO! But these last 2 have the
> >>>unusual problem that the brightness is WAY, WAY too high. It is not
the
> >>>case of a bad brightness pot because I can see a definite change when
it is
> >>>used. It is just that the range is way too high. I tried adding in
almost
> >>>1MOhm in series with the G2 connection to the picture tube and it was
still
> >>>dazzlingly bright. Is there a good way to drop the G2 somewhere
before it
> >>>gets ramped up (i.e. low voltage and low resistor)? John, is there
> >>>something I may have forgotten that I did the first time that I'm not
doing
> >>>on these last 2?
> >>>
> >>Instead of putting the 1 megohm in series with the G2 line try
> >>connecting it from the G2 line to ground.
> >
> >I don't get it. I figured G2 was voltage dependent. You are telling me
it
> >is current dependent and that I should bleed off current through a
parallel
> >connection to ground? That doesn't seem to make sense to me! Would
either
> >you or John please explain this before I put it into action?
> >
> G2 IS voltage dependent, but the 1 Mohm from G2 to ground would put a
> load on the G2 output of the flyback and cause the voltage to be lower
> and the brightness to reduce. It might very well get you to the
> brightness levels you need without damaging the flyback (it's a load,
> but not much of one).

 No joy. I went down to 500Mohms and there was no change whatsoever. I am
highly skeptical about this parallel shunt and am concerned about moving it
into the 100Kohms range (which appears is the only way to actually make a
difference). At this point I'll take theories but experience in dropping G2
would be best. Anybody????

BTW, Callan is also stuck in this state and I have tried 3 4600 chassis in
this machine with identical overbrightness...

As I recall, John had some
blurb in the *original* raster-hack text about "you might have to add a
resistor..." but the first time I did it, I did not have this problem so my
re-write did not include this tip and now John has replaced his original
text with my rewrite. Does anybody have the original text still?

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Received on Fri Nov 29 07:26:23 2002