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?
 
ThanksShaky 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"
Thanks for the reply JohnThe HV cage has its cover, as far as I know this is the original transformer and has the copper shielding. Pictures I have found on the net show a brick that also has copper shielding with the addition of the extra earth wire to the inner part of the transformer. I will see if I can video the fault and post the youtube link here.I will try the soft iron trick next, worth a shot :)
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