Re: 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 13:21:06 2003