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CGA to VGA

Printed From: ukVac.com
Category: Technical
Forum Name: Tech, Maintenance & Repairs
Forum Description: Need Help? Ask Here
URL: http://www.ukvac.com/forum/forum_posts.asp?TID=369762
Printed Date: 22 Apr 2019 at 7:41am


Topic: CGA to VGA
Posted By: Brendan1495
Subject: CGA to VGA
Date Posted: 15 Apr 2019 at 11:52am
Hi All, I am trying to set up a cab with lcd monitor and a GBS 8200 v4.00, whatever O try to do the picture is terrible and jumps all over if I try the board I am using through a supergun on the TV its great any help would be appreciated. Pictures below







Replies:
Posted By: Kev A
Date Posted: 15 Apr 2019 at 12:30pm
have you got the ground connected on the video cable, mine came loose once and something similar happened


Posted By: Brendan1495
Date Posted: 15 Apr 2019 at 1:02pm
Yes the grounds connected


Posted By: gunblade
Date Posted: 15 Apr 2019 at 2:41pm
it could be clamp and clamp sp settings


Posted By: Kev A
Date Posted: 15 Apr 2019 at 2:42pm
holding down one of the buttons on there preforms a factory reset, might be worth giving that a go, I think I also had to play with the clamp st settings on mine, and lower them to something like 04 and 05, rather than the default which is 90 something. although that was a color issue where it would gradually get more and more pink.


Posted By: ColinD
Date Posted: 15 Apr 2019 at 2:45pm
Kung Fu Master uses an odd screen format at about 55Hz refresh rate, so might be out of range ?


Posted By: Vamino
Date Posted: 15 Apr 2019 at 2:55pm
I also agree with the sync being slightly out of range and some adjustment to the clamp may be needed.

I messed around with mine for hours using a 24khz input and eventually got a decentish picture out of it, which wasn't too bad considering the price of the unit. I tried messing around to get the slightly washed out colours to pop but nothing helped. There was some interferrence but doing the following eliminated the remaining noise/fuzzyness.


The unit served it's purpose until I eventually bought an OSSC which is expensive when compared to the GBS8200, but I'm very happy with the OSSC and glad I made the purchase.


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Posted By: Brendan1495
Date Posted: 15 Apr 2019 at 4:52pm
Thanks for all your help, could anyone suggest a descent LCD monitor that would support 55Hz refresh rate


Posted By: sukhbir
Date Posted: 15 Apr 2019 at 5:38pm
Why use vga?you can pick up an old crt tv and use it’s scart rgb socket.you will hardly have any sync problems .the old TVs had generous line and field frequencies.


Posted By: Brendan1495
Date Posted: 15 Apr 2019 at 6:13pm
Would do but my cab is really narrow, no room for a CRT


Posted By: Brendan1495
Date Posted: 18 Apr 2019 at 8:33am
Got a CRT will try at weekend, thanks for the help


Posted By: ColinD
Date Posted: 18 Apr 2019 at 2:32pm
I'm tempted to suggest that your board has a fault that has materialised during your swapping, the horizontal lines missing also worries me.  Have you another different game pcb to try ?


Posted By: Brendan1495
Date Posted: 18 Apr 2019 at 2:57pm
At the moment I dont, but if I use a supergun on the TV the picture is fine no missing artifacts, but its black and white



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