Ken G. wrote:
I have an old asteroids full size vintage video game .
I has a black & white monitor .

When it first comes on its fine . Within 10 minutes the whole image gets
bigger , things disappear off the edges . The center of the screen gets
a bit darker .
I suspected the hi voltage diode off the flyback and adjusting the hi
voltage pot but replacing that did not help .

I dont have any model #s the monitor has one medum circuit board and
one small board with the flyback in a metal box .

Thanks


This is an XY monitor, the scan is very different compared to a normal tv.

Try this Page
http://www.gamearchive.com/Video_Gam...i/monitor.html

The fault sounds like b+ is going low, maybe a bad cap in power supply.
I think from memory its 123v to HT Generator Board.