Safe boot with 15 khz arcade monitor??

[fcobenitez]

Hi guys, thanks for all the amazing work
I want to know if it's possible to build a hardware solution that will detect when the videocard is outputting 15khz and only then turn on the arcade monitor. I know that exists the ATOM-15 BIOS flash method but my VGA doesn't support that (ATI 9250). I found this solution from the PC 2 Jamma project site, but from what I understood, it will only work with that particular ArcadeOS, and it dates back to 1999 from what I can tell.

http://pc2jamma.mameworld.info/phard.html

I know that a hardware solution exists, because I've been told that the Jamma ASD has the option of only letting the signal go through to the arcade monitor if its a 15 KHz signal, by using a dipswitch on the board itself.
My question I think, is 'would it be possible to implement something like that ArcadeOS option has, that sends a signal to the circuit linked above so it will turn the monitor ON after a 15 khz signal has been established? Or is it possible to DIY a hardware version like the one present in Jamma ASD?'

Thanks for your help guys

[chrisvg]

You could potentially use an arduino board with a simple circuit to toggle power going to the monitor based on the horizontal frequency.

A couple of months ago I worked on a similar project to auto switch modes on my MS2930 tri-sync monitor based on the hfreq being output via the VGA connector on my video card.  You can read up on the details of how I got it working at the following forum link

Hope this helps to give you some ideas!

[buttersoft]

...would it be possible to implement something like that ArcadeOS option has, that sends a signal to the circuit linked above so it will turn the monitor ON after a 15 khz signal has been established?

Closest I've found is this thing from Viletim - http://members.optusnet.com.au/eviltim/vga2arc/vga2arc.htm

It doesn't turn the monitor on or off, but it does cut the video.

[fcobenitez]

You could potentially use an arduino board with a simple circuit to toggle power going to the monitor based on the horizontal frequency.

A couple of months ago I worked on a similar project to auto switch modes on my MS2930 tri-sync monitor based on the hfreq being output via the VGA connector on my video card.  You can read up on the details of how I got it working at the following forum link

Hope this helps to give you some ideas!

Excellent reading material, I happen to have an Arduino laying around that would work, thanks for sharing your work!

...would it be possible to implement something like that ArcadeOS option has, that sends a signal to the circuit linked above so it will turn the monitor ON after a 15 khz signal has been established?

Closest I've found is this thing from Viletim - http://members.optusnet.com.au/eviltim/vga2arc/vga2arc.htm

It doesn't turn the monitor on or off, but it does cut the video.

I think that, for my purposes, it doesnt matter if it cuts the video or power off the monitors - thanks for sharing! I'm gonna read this now

Thanks you both for your help

[buttersoft]

I should have said, if you're going to build that circuit you have to program the PIC, and when you do you want to make sure it's using internal osc and reads the bit from the chip and writes it back correctly. I had to ask Tim about that last bit

I kinda like Chris's idea too. Though it's not automatic, is it?

[chrisvg]

I kinda like Chris's idea too. Though it's not automatic, is it?

Oh it is completely automatic, no manual control involved what so ever.  The code running on the Arduino is constantly polling the hfreq pin on the VGA port every 100ms and then running some code based on the output.  So, in my case it is then passing the reported value thru an if/else statement to toggle the MOSFETs which act as jumpers for the monitor sync mode (15/24/31 KHz) accordingly.

[fcobenitez]

Thanks buttersoft, I will print this page later so I won't forget those details. First must ask a friend if he could do that work, as he has the equipment needed to program the PIC I believe.

Chris, I like your idea, too! Never seen before that Arduino emulator on 123D before, looks super handy! Bookmarked that for later use.
I have two Aero City cabs, which have 15/24 KHz 25" monitors. I believe that, and please correct me if I'm wrong, I could modify your project so that the Arduino switches between both freqs depending on the output of the VGA, and if it tries to output anything else than 15 or 24 KHz, it would cut the signal going to the monitor, right?

Sorry if what I'm saying doesn't make any sense, the combination of my awful english and my begginer skillz of programming aren't of much help right now :p

[chrisvg]

Ah yeah, that 123D site is brilliant, I stumbled across it by accident, but so glad I did!

And yes, I think that would be possible to do, but my circuit is only designed to feed the monitor with one of the display mode settings, i don't have anything set up to cut the voltage going to the monitor.  So this would be something extra you would need to do.  If you got a simply relay switch that can be toggled on/off with a 5v line, you could easily control it with the Arduino.

[fcobenitez]

Thanks again, I'm looking forward to start working on this side-project! For now, I will just wait a minute after booting the PC to turn on the monitor :-)

[chrisvg]

Haha no worries, let us know how you get on with it if you decide to pursue it, sounds like a fun project

[krick]

The Ultimarc J-Pac encoder has a feature to prevent out-of-range signals from getting to your 15KHz monitor.  The only limitation is that it is intended to be used in a JAMMA wired cabinet.

https://www.ultimarc.com/jpac.html

Custom microcontroller only allows sync signals to be sent to the monitor if they are in the correct range that the monitor is designed for. Avoids driving the monitor with a too-high horizontal sync rate which can damage some arcade monitors.

[fcobenitez]

Yes, it's the same functionality that the JammASD has, and I believe it works somewhat similar to the circuit that buttersoft linked a couple post above
So far I think that using a modified version of Chris idea it's the best option