Re: shaky asteroids video

SIMON HANLON wrote:
> Hi list
> I have been trying to fix my asteroids cocktail that has shaky video
> for years on and off....today I got closer to the solution.
> The problem is worse during times when text is shown on the screen, I
> tried different monitors, different game pcb, different AR baords, Big
> blue etc...still the same. There was also a problem with humming on
> the sound...I thought the two were connected.
> The sound problem turned out to be a bad fuse F5 on the power brick,
> only half the AC was getting to the game PCB and this must have had an
> effect on the 22v that feeds into the audio section, replaced the fuse
> and the sound was normal.
> The wobble in the video is from the transformer being sat under the
> monitor in the cocktail layout, I pulled the monitor out to take some
> voltages and powered it up on the floor...picture was steady as a rock!
> I looked at some pictures of other asteroids cocktail power bricks and
> they seem to have an earth wire that goes into the inners of the
> transformer (internal shield maybe), mine doesn't have that wire. For
> now I have fitted a metal plate to the bottom on the monitor which
> helps a little but doesn't cure it 100%.
>
> Has anyone ever come across this before?
>
> Thanks
>
Shaky video is also related to the perforated screen on the HV cage. If
it is missing that can lead to shaking.

As for your brick - perhaps you have an upright brick instead of the
shielded cocktail version. Shielded ones have what looks like a copper
(bronze?) sheet just showing on the outer insulation wrap on the
transformer. You can try a piece of 'soft iron' between the transformer
and the monitor - as was used in Nintendo Dual cabinets - this (if
oriented correctly) should help shield the monitor from the transformer
magnetics.

For more info:

http://www.tpub.com/neets/book1/chapter1/1j.htm

John :-#)#

-- 
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
                 www.flippers.com 
"Old pinballers never die, they just flip out"
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