Electronics > Repair

MDA to VGA convertor / adapter

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free_electron:
I have endeavoured at replacing the pictures tubes in  some test equipment ( 3588 Spectrum analyser , 3589 Network analyser and 35665 Dynamic signal analyser. (i'm on a crusade to eradicate the last remaining 'vacuum glass balloons with metal scrap in em' from my lab, i have one that is very dim so it has to go )

I have established these are MDA monitors. ( old skool IBM style monochrome display adapters , essentially hercules at 720x350 pixels.

They have a hsync, vsync , video and brightness signal ( 2 level brightness , video toggles black / white , brightness controls 50% , 100% white)
clock is 18Khz like MDA.

I have found nice 9 inch LCD panels with 800x600 pixels that will fit the existing machine body nicely. these have VGA input and run of 12 volts ( the existing monitors also run off 12 volts, so that is a nice fit too )

so i need a MDA to VGA scan converter. those things are expensive on fleabay ...  you can get cheapo 30$ scan convertoers for EGA / CGA to resurrect old gaming machines . i wonder if those can handle MDA in any way.


Anyone has an idea , or better : anyone has a schematic ?

Shock:
This may interest you. I'm sure there is more on this elsewhere.

http://aknamunka.uw.hu/mdah/1st.html

krivx:
Simmcomm sell some rather expensive (~400usd) kits for replacing the HP 1345a display http://www.simmconnlabs.com/2136.html

The manuals show a small CPLD/FPGA board between the two. You might have to follow this custom route...

mikeselectricstuff:
Should be pretty straightforward with a FPGA and SRAM.
Might also be doable with a fast MCU that has an LCD output and camera input - I think there are some STM ARMs that do.


The fact it's only 2 bits per pixel means the bandwidth is pretty low, and may allow for some sneaky tricks like using SPI ports as video in/output shifters

free_electron:

--- Quote from: Shock on November 12, 2014, 09:31:27 pm ---This may interest you. I'm sure there is more on this elsewhere.

http://aknamunka.uw.hu/mdah/1st.html

--- End quote ---
overclocking is out of the question. this may be MDA but it is generated by a highly specialized motherboard. i am NOt messing with that  !

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