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evildragon
March 2nd, 2017, 09:09 PM
I made a post a while ago showing how to VGA mod an IBM PS/2 Model 25, but I never fully detailed it.

I made a YouTube video finally to change that, and finally remembered my login credentials to share it!

https://www.youtube.com/watch?v=KjnbSpuq90I

And of course, with because of the VGA mod, GeOS runs rather well: https://www.youtube.com/watch?v=1pMfODIHjRw

Any questions and I'll be happy to answer it. If you have questions as to why EGA 350 line doesn't work, I finally explained it in this video, after determining why it wasn't working on the Model 25 CRT. This is after reverse engineering the CRT's analog board.

luckybob
March 2nd, 2017, 10:13 PM
Everyone says "dont run your monitor in modes it does not support". Saying it will fry the monitor. Ok. But honestly, I'd like to see if this is actually true. I have 5 color 25's. 2 of them have horrible burn-in and are somewhat dim. I might have to give it a test.

http://www.thinkgeek.com/images/products/additional/large/ec07_for_science.jpg

evildragon
March 2nd, 2017, 10:24 PM
Everyone says "dont run your monitor in modes it does not support". Saying it will fry the monitor. Ok. But honestly, I'd like to see if this is actually true. I have 5 color 25's. 2 of them have horrible burn-in and are somewhat dim. I might have to give it a test.

http://www.thinkgeek.com/images/products/additional/large/ec07_for_science.jpg

The flyback is driven by the horizontal oscillator, it's a fixed frequency monitor. Ever remember that whining sound when you ran the wrong scan rate on a fixed frequency monitor? That's coming from the flyback, and yes, it'll cook it. Multisync monitors run their own, but not on a fixed frequency. I had a client once with a Tandy monitor, fixed frequency VGA. Dead, Tried to run 1024x768 at 60Hz on it, left it there for a couple minutes thinking it'd work, toasted the flyback, and needed a new one.

luckybob
March 2nd, 2017, 10:27 PM
I suppose you're right. I'm one of those people that will always test the wet paint signs.

Changing the subject slightly, are you planning on updating your signature?

evildragon
March 2nd, 2017, 10:37 PM
Maybe eventually, lol. I only just signed back in after a few years.

luckybob
March 2nd, 2017, 11:03 PM
oh... Well now I feel like an ass, because I had no idea you were gone.

evildragon
March 2nd, 2017, 11:18 PM
It's alright. It's only been 3.5 years. lol

I've spent a lot of time between jobs, layoffs, outsourcing, etc. So now I have more time again to post here.

evildragon
March 6th, 2017, 02:09 PM
Here's a page from the tech ref manual explaining how it only looks at the vertical polarity, which also proves how EGA 350 line mode will NOT work.

http://i.imgur.com/4NTs3N1.png