Re: Amplifone Trouble

A rather nasty cheat to check if the monitor guns are firing is to short
the collectors of the drive transistor for each colour to the chassis
common. Real bright line!!! Now in this case (Vector) it would probably be
a good idea to put a load resistor in series with the jumper wire - so who
has suggestions as the resistance, I'm busy with some sales and can't do
the calculations or pull out the schematics.

John :-#)#

At 09:01 PM 22/10/2002 +0100, Dave Langley wrote:

>Hi ...
>
>I powered up my Star Wars cockpit last night only for the Amplifone to
>fail. :o(
>
>
>This is What happened:
>
>Powered up ... after about 5 seconds of deflection chatter the monitor
>went quiet. No picture came on after the normal 10 seconds or so warm up time.
>
>After investigating the monitor I found F3 had blown.
>
>Replaced F3.
>
>Powered game up. Now I'm getting deflection chatter, the fuse does not
>blow again but still no picture. Eventually I get a dim glow at the
>bottom of the tube, like the gun is firing below the display area and I'm
>getting reflected light. There is no movement of this.
>
>I scoped the boards using XY mode and all was fine, though I did not test
>the Z (yet).
>
>I've measured the HV @ 19.5Kv which is fine.
>
>When you power the game up the deflection board's spot killer comes on
>briefly and then goes off as normal and when you shut it down it comes on
>again as the HV drains away.
>
>For what it's worth this game only has about 6 hours on it since a wintron
>was installed and previous to my fixing it up it had been disused for 12+
>years. I guess it's only to be expected when components have been this
>long without power. The boards have been recapped and all the jumpers
>replaced with solid core wire and new deflection transistors were fitted.
>
>
>So since I have HV I'm assuming that it's likely to be a deflection board
>problem? Any hints where I should look?
>
>Also does anyone have a working or otherwise deflection board that they'd
>sell/trade me? I'd quite like a spare at some point regardless of when I
>fix this.
>
>
>Dave Langley
>www.robotron-2084.co.uk
>
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Received on Tue Oct 22 15:44:33 2002