Arcade Monitor Blurry and flickering

[bradley1023]

Hello all

Bradley here, i was the one with the Loewe tv and trying to use the UMSA to display an image on it. Well after an explanation to my dad we decided to get a real arcade monitor  ,

being very excited to see an image on it, i made up a vga cable using 5 wires that goes to the arcade monitor chassis (which is a new one by the way that cam from Jomac). i didn't however connect vertical sync as the man i bought it from said i shouldn't need this however he hasn't connected a computer to an arcade monitor before only real arcade boards.

I was able to get a complete picture after playing with the 8 control knobs on the arcade monitor chassis board, (the vertical frequency knob is very touchy) but the picture was extremely blurry and flickering as bad as plugging the computer to a tv via s-video.

I didn't want to fiddle with frequency's because i don't want to blow up my expensive new monitor so i thought i would ask you guys  . i am still using the ATI Radeon 9200 with CRT emu-driver and i only tried running it at 640*480 60i resolution.

Any immediate thoughts, thanks in advance

[Yeltsew7]

I am thinking that it needs composite sync, which is why he said it didn't need vertical, because technically, it doesn't.  There are two things you can try:

1.  Download a program called WinModelines (http://www.geocities.ws/podernixie/htpc/modeline-en.html)  You can tell it to try to output C-Sync on pin 13, see if that makes it any better.

2.  If that does not work, then I am wrong all together or your card doesn't support outputting composite on pin 13.  If the it is the latter, you can try to run each sync line from the computer through a 1N4148 diode, and then combining them together into the sync input on your monitor.  These are very cheap parts, I picked up a 50 pack at radio shack for $2.

[Calamity]

i only tried running it at 640*480 60i resolution.

It's the interlace what looks blurry and flickering. Just try a progressive mode.

[twistedsymphony]

generally if the picture is blurry it's due to the focus control on the flyback (one of the knobs on the back of the big black box on the chassis).

It doesn't sound like you're running a video amp, if you're not and you're running a 15K monitor then you should be using an amp, something like this: http://www.ultimarc.com/vidamp.html

the output signals from a PC are much weaker than that of a arcade board, as a result you generally run into a "dim" image but sometimes have other problems like flickering or image fold-over. This is because the monitors are very sensitive to voltage differences and aren't designed for the kind of low levels that a Pc outputs.

Usually video amp adapters like the one I linked above will take care of your sync conversion too. If you still need to pick something up for a control interface you might as well buy a J-PAC instead since that handles both video and controller adaptation.

-----------------------
FWIW some monitors simply have trouble displaying interlaced modes... I know the Makvisions have trouble with this... the image in interlaced modes looks all jittery because it tries to display it like a progressive image.


Also what model/spec monitor are you using? knowing that would allow us to give more accurate advice.

[bradley1023]

Thankyou all very much for your replies, all very helpful

I changed the output from interlaced mode to a progressive mode and this dramatically improved the clarity, i however had to use a smaller resolution like 320*240 because 640*480 wasn't available in the list in a progressive mode, is it possible to add this?

I wasn't aware of the focus and brightness knobs on the flyback they were certainly helpful, playing with all the knobs makes it hard to find the clearest moment  but i think i got it not to bad. It is still however flickering to some degree, not the same way it was before, its a lot less unnoticeable but its there, so running this video amp should improve this? its not really having any dimness problems. The chassis is brand new from Jomac, the monitor i was told is a bit older, these were the numbers i found on it;

Sharp
A48JSK61X03 (A)
h4M904571 (P)

The J-pac sounds pretty promising, i know it also prevents signals over 15khz from going to the monitor which i thought would be good for it while the computer boots in 31Khz, its just a a shame it has so few button inputs because i need quite a few.

[twistedsymphony]

I changed the output from interlaced mode to a progressive mode and this dramatically improved the clarity, i however had to use a smaller resolution like 320*240 because 640*480 wasn't available in the list in a progressive mode, is it possible to add this?

320x240 (aka 240p) is the best you can get for progressive scan in the 15K frequency range... if you want 640x480 (480P) you'll need a monitor capable of accepting 31K signals... lots of more modern monitors are "Tri-Sync" meaning they support 15K, 24K ("medium resolution"), and 31K modes. most sit-down games made in the mid-90s were Medium resolution and most games made around 1999 or later use 31K and that was the most common until the LCD games started coming out.

This is why I asked what monitor you have... really the supported resolutions have everything to do with the chassis and not much to do with the tube itself.

It is still however flickering to some degree, not the same way it was before, its a lot less unnoticeable but its there, so running this video amp should improve this? its not really having any dimness problems.

I honestly have no idea if a video amp will fix your issue... I've never tried running an arcade monitor from a PC without one. lots of newer arcade monitors don't need a video amp because they're designed with PC use in-mind. but I don't know about your specific chassis.

The chassis is brand new from Jomac, the monitor i was told is a bit older, these were the numbers i found on it;

Sharp
A48JSK61X03 (A)
h4M904571 (P)

Those look like tube numbers and what we need to know is your chassis model. you'd probably be best off just asking Jomac what modes your monitor supports and if it requires an amp... you might also ask him about your flicker and clarity issues.

The J-pac sounds pretty promising, i know it also prevents signals over 15khz from going to the monitor which i thought would be good for it while the computer boots in 31Khz, its just a a shame it has so few button inputs because i need quite a few.

I have 3 J-pacs and I'm pretty happy with them. there's actually a jumper on it to allow for 24K or 31K if your monitor supports those modes.

It supports 2-players with 8-buttons each, not including start or coin... I wouldn't expect it to support any more because 6-buttons and 2 players is essentially the maximum supported by the JAMMA+ standard and the J-PAC is designed to be plug and play with JAMMA cabinets. How many buttons do you need? If you need more you can always get an I-PAC in addition to the J-PAC... I would just make sure your cab doesn't end up like this: