Arcade board dilemma

[Irongiant]

So here's my dilemma - I have a few arcade game boards which I need to test but which put out a 25 KHz horizontal scan rate. My standard res test monitor won't of course handle this (it's a 20 year old Sony KX-14CP1 - an otherwise excellent monitor). My PC's VGA monitor is an Iiyama Vision Master Pro 410 - this does support horizontal scan rates as low as 27 KHz so would that perhaps handle a 25 KHz signal? I would imagine it wouldn't lock onto it and am loathe to try it in case of problems.

So, assuming both of the above monitors are useless as they stand, what's my best option?

I don't really want to get hold of another monitor (I'm kind of attached to my Sony and I doubt if I could get hold of a modern VGA monitor these days which will handle 25 KHz horizontal scan rates). I was thinking of a scan doubler of some description but I'm not aware of any that handle a 25 KHz input.

How about a compact LCD panel that handles 25 KHz and RGB (plus 50 and 60 Hz vertical scan rates) - does such a thing exist?

Any suggestions please anyone on the best way to achieve my aim, ie displaying 25 Khz on any of my existing monitors via some kind of additional device? Perhaps a circuit exists which I could knock together and so display the results - the output doesn't have to be perfect, just readable that's all.



Thanks

[NeWmAn]

A scan converter? Something that support EGA like this:
http://www.micomsoft.co.jp/xvga-1pro.htm
or this:
http://www.converters.tv/products/vga_to_cga/425.html
Those aren't cheap, but maybe you can find something cheaper on ebay...

Regarding LCD panels: it seems they only do 15 and 31KHz, but some Plasma TV are capable of 15,25 and 31 Khz.

I would try your Iiyama before everything else, if that fails a dual freq arcade monitor, an old multisync monitor or (if you can find it) an EGA monitor will probably be your only choices.
                 

[blackevilweredragon]

an EGA monitor won't work, they require TTL level RGB inputs (Digital)...  I think they also use RGBI if I'm not mistaken.

Usually all VGA monitors support the EGA scanrate..  it should work..

EGA's highest scanrate is actually 21KHz, so then it without a doubt should work..

[Irongiant]

Thanks. Re the EGA - I guess the best way to test this (bearing in mind the boards are untestable right now as they're kind of dead ....... ) would be to get hold of some Windows software that allows me to adjust the scan rate and so simulate 25 KHz ...... does such software exist?

[blackevilweredragon]

Thanks. Re the EGA - I guess the best way to test this (bearing in mind the boards are untestable right now as they're kind of dead ....... ) would be to get hold of some Windows software that allows me to adjust the scan rate and so simulate 25 KHz ...... does such software exist?

http://dosgames.com/dl.php?filename=ftp://...al/egaroids.zip

that game may run on Windows, but it's a DOS game..  mainly, EGA was for DOS and early versions of Windows (ie:  Windows 1, 2, 3)...


the vertical scan-rate may be high though, like 70Hz...  check that first, your monitors OSD usually shows this information..

EDIT:  Yea, if the Vertical Hz is 70, then the video card is outputting a non-EGA format..  I just read that VGA monitors don't truly support EGA so VGA cards outputted them at a slightly higher vertical sync to compensate bringing up the H Sync..

[NeWmAn]

I guess the best way to test this (bearing in mind the boards are untestable right now as they're kind of dead ....... ) would be to get hold of some Windows software that allows me to adjust the scan rate and so simulate 25 KHz ...... does such software exist?

Yes, it does!
Powerstrip:   http://www.entechtaiwan.com/util/ps.shtm

[Irongiant]

Thanks to you all for the suggestions, I'll give them a go.

I have though just tried Powerstrip and the monitor won't go any lower than 27 KHz as suspected, so looks like I'm back to looking for an upscan convertor or another test monitor, what a pain .........

Do any 'recent' CRT VGA monitors go as low as 25 KHz?

[viletim]

Irongiant,
A few years ago I did test some of my VGA monitors and one did go sync down to 25kHz...

Realistically, you probably don't have any real choice other than a proper 25kHz fixed frequency monitor. There really arn't a lot of options available when your video signal's horiz. frequency lies in the forbidden zone between 17 and 27kHz.

[Irongiant]

Thanks. Can't see anything suitable on Ebay so does anyone have any ideas where on the 'net I could buy a suitable old monitor please? The cheaper the better.

[ken_cinder]

By arcade definition, what you would be looking for is a medium resolution monitor.

See - http://easymamecab.mameworld.net/html/monitor9.php

As stated, this "no-fly" zone in the range you're looking for, is just that. You're pretty restricted in what you will find, and medium resolution monitors are:

1: Not popular in use, there aren't many games that make use of them (What is the game in question here?)

2: Quite expensive due to their inherent nature of being less used, and less popular, thus less produced.

3: Harder to come across than a standard or extended resolution monitor.

[Computolio]

   If it helps, Apple once made a fixed-frequency 24 KHZ monitor. It was called the Applecolor 12' RGB or something like that. It was mostly used with LCs and ][sis.

   Failing that, any combo monitor should be able to sync to 24 KHZ. There's a big list of combo monitors on the wiki.

[Irongiant]

If it helps, Apple once made a fixed-frequency 24 KHZ monitor. It was called the Applecolor 12' RGB or something like that. It was mostly used with LCs and ][sis.

    Failing that, any combo monitor should be able to sync to 24 KHZ. There's a big list of combo monitors on the wiki.

Would the Apple monitor you mentioned be this one:

http://www.monitorworld.com/Monitors/apple...splaym1299.html

[Irongiant]

By arcade definition, what you would be looking for is a medium resolution monitor.

See - http://easymamecab.mameworld.net/html/monitor9.php

As stated, this "no-fly" zone in the range you're looking for, is just that. You're pretty restricted in what you will find, and medium resolution monitors are:

1: Not popular in use, there aren't many games that make use of them (What is the game in question here?)

2: Quite expensive due to their inherent nature of being less used, and less popular, thus less produced.

3: Harder to come across than a standard or extended resolution monitor.

Thanks. I just wish there was an 'easy' way to use my existing 15KHz or VGA monitor, but life ain't that simple.

[ido8bit]

A lot of old multisync monitors such as the 1st NEC Multisync, Multisync 2 (not 2A) and 3D (and various others from other manufacturers) will do anything from 15-35kHz.  

Check the monitor lists on the Amiga related sites.  A couple of AGA modes were 24-26kHz from memory so anything listed as working in all modes should work.  

[Irongiant]

Thanks, now managed to snag an Iiyama Vision Master 17 which syncs down to 24 KHz and it works just fine. :-)