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

From: Gregg Woodcock <woodcock_at_sisna.com>
Date: Sun Aug 04 2002 - 01:13:09 EDT

OK, here's an update. I have confirmed a working power supply and game
board (fires up a W-G monitor). I metered the heater and it is still good.
Before I began the operation, I had heater glow. After removing the 2 wires
from the HV controls, I have no heater glow and no 6.3VAC on the brown
twisted pair to the tube. Something is kiling the heater and that is the
problem. Is it something in my procedure below? Also, I forgot a couple of
things last time so here's the correct summary:

> I put in an IT (1:1) and wired up the 4600 chassis.
> I kept the 4600 yoke and pulled the green RGB PCB.
I grounded the chassis to game/earth ground.
> 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 on Amplifone.
> I clipped a 3 (5?) Watt carbon 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 her up but could not see heater and got no picture.
>
> 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 Sat Aug 3 22:27:23 2002

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