Re: Very Dim Asteroids Monitor Problem

I'm certain now that the newer EHT won't work in an older G05 monitor. The
newer one takes an input voltage of 40v while the older one only requires
25v. So, I guess I just need to find an older EHT unit - or at least my
friend does. :)

Matt
----- Original Message -----
From: "Matt Rossiter" <rossiter@ni.net>
To: <vectorlist@synthcom.com>
Sent: Friday, January 24, 2003 1:19 PM
Subject: Re: VECTOR: Very Dim Asteroids Monitor Problem

> Well, I checked the input voltages and they look fine to me. This is a
> G05-801 model so I'm getting 30vac and 6.3vac like I should. The
deflection
> board is getting +/- 25 volts like it should. The EHT input voltage is
25v
> which should be fine.
>
> But everything from the EHT seems low. And I've tried swapping one in
that
> I know is working. So, instead of getting 400v I get 345v for the focus
and
> 70v instead of 90v for the Z-amp. The tube is only getting about 10kv at
> the Anode. I'm a little confused with Pin-1 on the EHT which I think
goes
> to G4 on the CRT. I'm getting 45 volts.
>
> I'm looking at the schematics for the G05-801 EHT and comparing it with
the
> 802 model. It looks to me like they are different. Maybe someone swapped
> in a newer model and that's why the EHT is so low? I know that the older
> monitor has different voltage requirements.
>
> Has anyone ever successfully swapped in a model 802 EHT into an older 801
> monitor?
>
>
> Matt
>
>
> ----- Original Message -----
> From: "John Robertson" <jrr@flippers.com>
> To: <vectorlist@synthcom.com>; <vectorlist@synthcom.com>
> Sent: Friday, January 24, 2003 11:43 AM
> Subject: Re: VECTOR: Very Dim Asteroids Monitor Problem
>
>
> > Yup, as I thought...check the Z-Axis section, you will see that the
90VDC
> > is separated into two sub circuits, the cathode, and Grid1, this is
> > adjustable from roughly 45VDC to 0VDC by a pot, and the cathode is
> > controlled by transistor Q504.
> >
> > You do need the 90VDC...if low, check diode (not a 1N400X - too slow)
and
> > filter cap(s) in the circuit.
> >
> > John :-#)#
> >
> > At 12:22 AM 25/01/2003 -0800, Matt Rossiter wrote:
> > >I've been Looking at this early verion of the G05 with the extra
> regulator
> > >PCB and the problem is the monitor is very dim. The tube is fine, but
> the
> > >Grid-1 voltage is only 10v when the brightness pot is turned all the
way
> up.
> > >Normally is should be around 30-35v for a good picture. The Z-amp
> voltage
> > >is only about 70v when it should be around +90v, but I think that
should
> > >still be ok.
> > >
> > >This is probably a simple question, but if the most I'm getting is +10v
> with
> > >the brightness pot turned all the way up, what should I be checking
for?
> > >I've checked the brightness pot and it's ok. The voltages coming from
> the
> > >regulator PCB look ok. The tube and yoke are fine. And the monitor
has
> new
> > >electolytic capacitors. Anybody?
> > >
> > >Here's the manual if anyone cares to take a guess.
> > >http://www.spies.com/~arcade/manuals/G05-tm146.pdf
> > >
> > >
> > >Thanks.
> > >
> > >
> > >Matt
> > >
> > >
> >
>
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Received on Fri Jan 24 14:14:11 2003