Has anyone attempted or even know if it is feasible to take a multisync monitor and force it to only accept 640 x 480 ? I have some video experiments that I would like to attempt and disabling a surplus monitor in this manner would be helpful. Maybe someone could point me to some commercial monitor schematics for me to study.
Thanks Jim
Rather than trying to modify the circuitry inside the monitor, why don't you build a circuit that monitors the sync signal on the video, and cuts the connection if the signal doesn't have the timing that you want? That'll be much more universal than trying to reverse-engineer a monitor, if less compact.
If you're clever you could even steal power from the monitor to make it work.
sure, buld a circuit that counts horizontal pulses between vertical pulses and if it sees the wrong total turns off the power (or the signal)!
"MultiSync" is (R) by NEC - are you interested in other brands too?
What do you really want the monitor do when it sees "incorrect" input? how do you define correct?
study.
They're probably not going to help you much everything is controlled by a microcontroller.
study.
The solution is to find and use a vid card that only puts out that array.
Oh and there are PCI to ISA converters so you can use an old card.
I agree. This is the most simple solution by far. A simple microcontroller will do just fine.
Most multisync (multi frequency) monitors have a PLL in a sync detector plus a bunch of Mosfets to switch between the frequency ranges. Blocking certain frequencies would require rewriting the monitor's firmware.
Make or find a VGA cable that disconnects the lines that are used for monitor identification. Old-style VGA didn't use all fifteen pins, some of the 'unused' pins are where the monitor identification information is transferred. That's pins 4, 9, 11, 12, 15.
Then, the video card doesn't get any hints from its monitor, and should obey software control.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required