Build Your Own Arcade Controls Forum

Arcade Collecting => Restorations & repair => Topic started by: Mauzy on July 07, 2008, 10:00:58 pm

Title: Cant finish a Galaga with a half-dead Gallag board
Post by: Mauzy on July 07, 2008, 10:00:58 pm

To make this short since this is the second time typing this out, I socketed the Z80 sync bus controller daughter card on my Gallag board backwards while simultaneously plugging the main board in backward at the harness as well. Ive been kicking myself for 3 weeks over this.

It was totally dead (no picture) until I replaced all but one IC on the Z80 sync bus, and now the game comes up like this:
http://www.youtube.com/v/M9XM9lzhfHo&hl=en&fs=1

It wont boot at all without the galaga enhancement pack installed, but It can be played perfectly fine, its just hard to see.

How do I go about trouble shooting the video problem? All the info I can find is a poorly scanned set of schematics that has a page missing.

BTW: the green in the monitor is a problem Ive been having for a couple years even with the game running fine. I did plug in a different game and It came up perfectly fine.

Title: Re: Cant finish a Galaga with a half-dead Gallag board
Post by: Blanka on July 08, 2008, 02:00:26 am

I heard most malfunctioning boards suffer from over-age capacitors. They die rather quick and are the main candidates for malformed video. Check them.
With the green it also looks like the video-circuit sends out a sync-on-green signal, whereas the monitor does not care about that :D.

Title: Re: Cant finish a Galaga with a half-dead Gallag board
Post by: Mauzy on July 08, 2008, 12:03:12 pm

Theres only one cap on the game board itself, and that was fine until the day it was plugged in backward. As for the green, I had assumed that is was from this:
http://forum.arcadecontrols.com/index.php?topic=74524.0

Thats a topic I started about this monitor almost a year ago, though now that I think about it, no matter what was on the screen (whether it could sync or not) the green scanlines would cover the entire screen, so i guess the green may be a board thing... GAH!

Title: Re: Cant finish a Galaga with a half-dead Gallag board
Post by: Mauzy on July 08, 2008, 06:04:50 pm

So i was wrong on the cap issue. Theres actually several caps on the main board and a couple on the video board.  :dizzy:

At one point during testing, the Sync bus was socketed one pin off, which resulted in garbage, but the garbage was MULTI COLORED. Resocketed the sync bus, and it continued with the blue, crazy sync issue...