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

From: Gregg Woodcock <woodcock_at_sisna.com>
Date: Fri Aug 09 2002 - 17:26:03 EDT

----- Original Message -----
From: "John Robertson" <pinball@telus.net>
To: <vectorlist@synthcom.com>; <vectorlist@synthcom.com>
Sent: Sunday, August 04, 2002 2:42 PM
Subject: Re: VECTOR: Anybody done John's Raster Hack for Ampliphone?

> In thinking this over (and not having the schematics at home...) I DID use
> the 4600 socket with the 4600 chassis and simply removed the output
> transistors. This left the Screen Control (the 1Meg pot) on the neckboard
> for your brightness. Note the addition of the 1 ohm resistor to reduce
> inrush current to the tube, probably not required, but I didn't try it
> without - however as the monitor is hooked to the original heater circuit
I
> can see where that resistor is redundant and can be not installed - thus
> keeping the heater circuit as original on the 4600.
>
> So, you are removing the Ampliphone HV board AND the Ampliphone tube
socket.
>
> Remember that you must have the 4600 YOKE hooked up and placed way off to
> one side (so it won't interfere with the picture...)
>
> When you get around to pictures take a couple of the modified neckboard
and
> I'll rewrite the docs to fit them in...I'm going to edit them right now to
> reflect this conversation to date...

I don't know if I'll be able to get pictures but they shouldn't be needed
with this rewrite:

Replacement HV for Ampliphone XY monitors

0) Turn off the dead game and remove the power cord from the wall. Keep it
this way for the entire procedure.

1) Double-check your 4600 chassis to make sure it works. Remove the RGB
board and set it aside (spare parts now). Cut the black wire from the neck
PCB that goes to the DAG (spring which is strung around the perimeter of the
picture tube) leaving at least 6 inches attached to the neck PCB. Remove
the PCB (and metal sled/skid) from the monitor chassis and the yoke from the
picture tube. Drill holes in the metal sled/skid in the 2 corners which do
not already have them. Using 4 screws, mount the skid/sled to the inside of
the cabinet underneath the HV PCB with the power cord hanging down and the
secondary anode cable pointing up. As you screw this down, connect one end
of an earth ground to the skid/sled (at 2-4 feet long). Make 2 mounting
straps by twice stringing a thick nylon cable tie through a fender washer
then around the yoke Screw the yoke to the side of the cabinet somewhere by
screwing a screw through each fender washer. Make sure all 4 yoke wires are
still properly connected to the 4600 PCB. Using 2 more wood screws, screw
the focus assembly of the 4600 to the inside of the cabinet above the
Amplifone HV PCB. Connect the secondary anode of the 4600 to the picture
tube.

2) Remove 4 screws holding down the "transformer block" and flip it over.
At the black/white/green AC connectors, screw down an additional black/white
AC pair and run this through the cardboard fuse cover's hole and out the
top. I have a TON of PC power supply cords with the computer end cut off
(which I use to replace dead switchers in more modern arcade games); these
are GREAT for this wiring. Wire this to the input of your isolation
transformer. On the other (output) end of the isolation transformer, crimp
on a 2-pin molex that will power your 4600 AC input. Screw the isolation
transformer down on the floor of the game to the left of the transformer
block. Screw the transformer block back down and connect the other end of
that earth ground wire to the frame of the transformer block. Hook it up
the 4600 AC connector to the isolation transformer AC output.

3) Remove the dead Amplifone HV PCB and desolder these 4 wires: the 2 brown
twisted pair (heater), the solid white from behind the "focus" wiper and the
white with black stripe from behind the "screen" (brightness) wiper. Wind
up the original secondary anode cable and cable tie it to the HV PCB somehow
(keeping the tip pointing outward and away from the PCB and heat sink just
in case there is still some HV working). Replace the HV PCB and screw it
back down.

5) Take a 3-5 Watt carbon resistor, cut off 1 leg and throw the resistor
away. Solder this leg to the focus (plain white) wire. Keep the rubber
insulator around the wire. Push this pin into the focus pin of the neck
board of the 4600 (this is the pin all by itself away from the others which
has the socket "key" around it). Push the rubber insulator all the way down
to cover the soldered area. Push the other 3 wires from the top of the neck
PCB through the center hole. On the bottom of the neck PCB, solder as
follows: Solder each brown wire to a pin labeled "H" (for "heater").
Solder the white with black stripe wire to the pin labeled "G2"
(brightness). Lastly, take the DAG (ground) wire (hanging from the corner
of the 4600's neck PCB) and either add it to the connector of the
Amplifone's dag or solder it to the DAG where the original Amplifone's wire
is soldered. If you do not ground the game, the picture will oscillate in
brightness (1-3 Hz); this is your clue you do not have common/logic ground
between the monitor and the game PCB.

6) Plug the game in and power it on and adjust the picture. The only 2
controls on the 4600 that do anything useful now are the "focus" and
"brightness" controls.

P.S. I was going to send you $10 (I am totally serious) and I will the next
time I use this but I figure this rewrite is worth at least $10 since the
original version was not very useable (i.e. this one will generate a LOT
more use/interest/$10)...

---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to vectorlist-owner@synthcom.com.
Received on Fri Aug 9 14:41:10 2002

This archive was generated by hypermail 2.1.8 : Fri Aug 01 2003 - 00:33:37 EDT