Sega Astro City problem with some games

[Demetris74]

Hi Guys

I have a Sega astro city and bought some games recently, It seems that old games have scrambled graphics or thats not the case?

Golden axe, pit fighter . other games i like bad dudes, Solomons key tekken, work fine.  Is it something to do with the Monitor sync? the monitor of the astro city is 15/24khz its a Nanao.

Is it something i can work out from the monitor chassis? i tryed with the front panel horizontal/ vertical e.t.c but no success

it shows like scrambled graphics

http://i785.photobucket.com/albums/yy134/info318/WP_20140616_004_zps40cf6f0f.jpg

Appreciate your help

[John's Arcade]

Does the monitor chassis have a jumper to select either 15k or 24k? I think it does. Are you changing that setting to match the PCB?

http://forum.arcadeotaku.com/viewtopic.php?f=4&t=6623

[Demetris74]

Does the monitor chassis have a jumper to select either 15k or 24k? I think it does. Are you changing that setting to match the PCB?

http://forum.arcadeotaku.com/viewtopic.php?f=4&t=6623

Hey John

Done this before, changed position of the molex to 24khz and back to 15khz no change.

What i have read is that some Bootleg games have this problem with sync on astro city dont know if thats a fact

rgrds