Is it safe to use an MDA monitor with a mono EGA output?

[CompaqGuy1993]

Is it safe to use my ET3000AX EGA mono output with my MDA monitors? I've read some combinations of CGA/MDA equipment can damage each other.

 

[dorkbert]

"No."

 

[Hugo Holden]

Is it safe to use my ET3000AX EGA mono output with my MDA monitors? I've read some combinations of CGA/MDA equipment can damage each other.

It depends on the design of the particular VDU, whether or not it can be damaged by an abnormal H sync or H drive signal.

For VDU's which do not have their own H scan oscillators, it is not a wonderful idea to drive them from a non standard H sync signal (H. Drive).

However for designs that have their own independent H scan oscillators and rely on synchronizing to the incoming H sync pulse, there is no problem at all, because if the incoming sync frequency is way off the scan oscillator simply loses lock and runs close to the correct frequency and no harm is done to the set's H scan output stage. Of course all TV's were made like this because sometimes, between channels for example, the sync pulses would just be extreme noise.

You would really have to look up the design/schematic of your particular MDA monitors to figure out if they could be harmed, or not, by an abnormal frequency H sync. Generally though, one big clue is that if the VDU has an H.Hold control, it will have its own internal H scan oscillator and be immune from damage from incorrect syncs.

 

[Eudimorphodon]

FWIW, according to this manual:

https://www.dosdays.co.uk/media/tsenglabs/Tseng%20Labs%20Qtec%20VGA%201024%20ET3000-AX%20Manual.pdf

You can hook an MDA monitor to that card if you set the switches appropriately, but all you’ll get out of it is MDA/Hercules emulation. (It does not appear like it emulates a “real” EGA card with an MDA monitor attached. Which is a vanishingly rare and poorly supported combination so emulating Hercules instead makes some degree of sense.) Seems like kind of a waste, but that is also how old OAK cards with dual monitor ports behave.

 

[CompaqGuy1993]

FWIW, according to this manual:

https://www.dosdays.co.uk/media/tsenglabs/Tseng%20Labs%20Qtec%20VGA%201024%20ET3000-AX%20Manual.pdf

You can hook an MDA monitor to that card if you set the switches appropriately, but all you’ll get out of it is MDA/Hercules emulation. (It does not appear like it emulates a “real” EGA card with an MDA monitor attached. Which is a vanishingly rare and poorly supported combination so emulating Hercules instead makes some degree of sense.) Seems like kind of a waste, but that is also how old OAK cards with dual monitor ports behave.

Ah! Thank you for that link, I couldn't find anything like that!