Top of video display curling

avramce

Kabuki Klasher
Joined
Sep 24, 2019
Posts
125
Hi all, I have a MV-1 board that has an issue where the top of the display curls to the right. At first I thought my monitor was flaking out, but confirmed that my other boards do not do this on the monitor.

Is this something a recap would fix? I tend to hear recapping for audio problems, but does recaps help visual, or is that IC issues?

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ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
I recently came across this too. I got a 4 slot cabinet with a MV4FS and MS8-26SG monitor that and a curve at the top. No amount of tweaking the pots would help. Pulled the monitor and was doing testing with an MV2F, which also had the curve. Figured it was the monitor chassis, recapped it, no change. Spent a bunch of time testing/verifying components on the chassis, didn't find anything bad. Swapped to using a random jamma board, curve was gone. Further testing with other neo geo boards showed a correlation between boards that use the NEO-I0 chip to generate the sync signal and there being a curve. Perhaps its outputting a slightly malformed signal that causes problems for some monitors.
 

Dochartaigh

Edo Express Delivery Guy
Joined
Mar 25, 2017
Posts
337
Don't know if this will help, but when this happens on professional CRT's (usually higher-end ones like BVM's) we commonly use an Extron RGB interface with the SERR dipswitch turned on. It'll help with the sync and get rid of the skew (also known as flagging) on the top of the screen.
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
Yeah, that devices does what I was thinking about too. I'm looking at getting a jrok sync cleaner and see if that fixes it.
 

awbacon

Kyokughen Trainee
10 Year Member
Joined
Jan 28, 2009
Posts
4,220
Yeah, that devices does what I was thinking about too. I'm looking at getting a jrok sync cleaner and see if that fixes it.

I'd def try messing with the sync levels. MVS sync is not "standard", so your monitor just might not be cool with it
 

wyo

King of Spammers
10 Year Member
Joined
May 22, 2013
Posts
10,109
This issue is also present when using an AES with certain monitors such as the PVM-20L5.
 
Joined
Mar 17, 2015
Posts
41
Interesting. I had to adjust that same “curl” out of mine by messing with horiz and vert sync despite the monitor not having the same issue with test PCBs.. now I’m wondering if it’s my MVS-2 board that could be causing the issue.

Been meaning to do it anyway.. just ordered a cap kit for the board.
 
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