Supergun Image Color Problems..

Black IcE

Black IcE

Earl's Long Lost Brother,
15 Year Member
Joined
Jun 29, 2005
Posts
924
I am having problems with certain boards having weird or distorted/changed screen colors. I am currently using a neobitz encoder. The color problem occurs in both composite and s-video. The colors are fine with my MV-1f and all CPS1 and CPS2 games. The games that I tried that DID have the color problem were Rastan, Heavy Barrel, WWF Wrestlefest, Mortal Kombat 1, and Mortal Kombat 2. It was suggested that I try a lm1881 sync seperator circuit, which I will be trying this week. I am also working with Jeff on this, but I wanted to see if anyone else has any thoughts on this.

Thanks in advance for the help.
 
ttooddddyy

ttooddddyy

PNG FTW,
Joined
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8,335
Black IcE said:
I am having problems with certain boards having weird or distorted/changed screen colors. I am currently using a neobitz encoder. The color problem occurs in both composite and s-video. The colors are fine with my MV-1f and all CPS1 and CPS2 games. The games that I tried that DID have the color problem were Rastan, Heavy Barrel, WWF Wrestlefest, Mortal Kombat 1, and Mortal Kombat 2. It was suggested that I try a lm1881 sync seperator circuit, which I will be trying this week. I am also working with Jeff on this, but I wanted to see if anyone else has any thoughts on this.

Thanks in advance for the help.
Click to expand...

Im not sure about the other boards but the MKs are known to have problems with some encoders, I use AD724 and 725 encoders and have been unable to get it to work with the MK2 board set (despite hours of experimenting with sync spliters and RC circuits to modify the sync waveform) These boards run at 53 Hz btw not 60 Hz like most - It may have something to do with this, never been able to figure it out.

I could only get the ADs to work flawlessly with MVS, all other boards had issues.
MKII was the worst.

What encoderIC is in the neobitz, Sony ?
 
Last edited:
Black IcE

Black IcE

Earl's Long Lost Brother,
15 Year Member
Joined
Jun 29, 2005
Posts
924
The neobitz uses an AD724. It works beautifully with my MVS and all my capcom games. The colors are tweaked on the other boards though. What are the image quality differences between a sony chip and the AD72X series?
 
Dean

Dean

Choi's Clawmaker
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Posts
4,821
You need the sync separator. This is the hallmark of sync issues with the AD series of chips.
 
Black IcE

Black IcE

Earl's Long Lost Brother,
15 Year Member
Joined
Jun 29, 2005
Posts
924
Thanks, I will be putting one together this week. Also, D-Lite... I know I am referring to an old project, but I read through the thread for the "LoadedGun" last night and I was very impressed. I thought it was very cool. I figure no need to resurrect the thread, but I just wanted to say that. Thanks again for the help.
 
J

JMKurtz

Tech Support Moderator,
20 Year Member
Joined
Aug 12, 2000
Posts
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The LM1881 may help in some cases, but not all. It's worth having as it does improve compatibility. An addition to the basic LM1881 circuit, that is not mentioned on the gamesx.com diagram that most people use, is a low pass filter which could also help out.

You need another resistor and cap in your circuit. Here is a link the LM1881 datasheet with more info:

http://www.national.com/ds.cgi/LM/LM1881.pdf

Unfortunately, not all arcade boards are created equal (and definitely not designed for consumer TVs), so we'll always run into compatibility issues.

Jeff
 
ttooddddyy

ttooddddyy

PNG FTW,
Joined
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Posts
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A digital scopes image of the videos front porch with sync pulse and chroma burst signal out of the encoder may be usefull to compair the MVS, which works perfectly, with the MK2 board (which does not). I am not able to capture this with my scope, anyone else?
 
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