Re: Anybody done John's Raster Hack for Ampliphone?

----- Original Message -----
From: "John Robertson" <pinball@telus.net>
To: <vectorlist@synthcom.com>; <vectorlist@synthcom.com>
Sent: Saturday, July 13, 2002 2:10 PM
Subject: Re: VECTOR: Anybody done John's Raster Hack for Ampliphone?

> There needs to be a 1 ohm resistor. You have to check the raster chassis
> that you are using to replace the vector HV chassis for the presence of
the
> resistor. If it is not there you need to add one to the filament circuit,
> if it is there then you do not need to add it.
>
> I don't recall the details on this modification it's been too many years.
> You are unlikely to have any problems if you consider that you are
starting
> with a working raster chassis and yoke, and are simply hooking up the
> screen, HV, and focus lines to the original tube.
>
> I did not go into a lot of detail as I wanted only people that are
familiar
> with monitor repair to attempt this operation - it is a 'hack' job and
thus
> you really have to understand the principles behind the operation.

OK I tried it and though I *do* how have full HV, I do not yet have a
picture. Let me rephrase John's hack and you tell me if you see anything
wrong with what I did.

I put in as IT (1:1) and wired up the chassis.
I kept the yoke and pulled the green RGB PCB.
I put replaced the original secondary anode connection to the tube with the
one from the 4600.
I ripped off the 2 wires going to the socket which were connected to the
focus and screen controls.
I clipped a 3 (5?) Watt ceramic resistor's leads and soldered one to each of
those 2 wires.
I pushed the "screen" wire into the 4600's "G2" pin.
I pushed the "focus" wire into the 4600's (unlabeled) focus pin (the offset
pin).
I fired here up but could not see heater and got no picture.
This is a known working 4600 but an unknown Star Wars (maybe bad deflection
or game PCBs).

The only thing that concerns me about my approach is that inside the neck
socket of the amplifone is a 10K resistor in series with the focus wire. If
I am reading (into) John's notes correctly, he soldered onto the other end
of this resistor, removing it from the circuit, right? This may or may not
be OK with the extra resistance but the worst case is that I should at least
get a very blurry picture, right? The other thing that concerns me is
John's notes allude to eliminating the neck board altogether which I don't
see as possible because the only screen control available is on the neck
board, right? How would one control the brightness?

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Received on Wed Jul 31 06:25:59 2002