Colors off on working 5154 EGA monitor

[marcampion]

Hi! I recently got this supposedly "working perfect condition" 5154 on ebay. When I connect it to my AT though, the colors are off. The DOS prompt which should be black is red/magenta. I seem to get no blue at all.



Why could this be?

When I got it, it blew up on me after like 10 minutes, giving up smoke. I knew this was a recurrent issue with these monitors, I took it to a shop, they fixed it, but the screen is still red. The screen was always red, even before the power blowing up. Before I take it back to the shop wondered if people have suggestions.

Thanks!

 

[modem7]

I seem to get no blue at all.

According to the additive colour triangle at [here], if there was no blue, your white text would be yellow.

It looks like the red is not turning off at the required times.

Why could this be?

Have you proven that your EGA video card is good (on another EGA monitor) ?

 

[modem7]

On a lot of EGA cards is jumper that controls what is sent to the monitor on pin 2 of the 9-pin D connector.
The diagram at [here] shows that on IBM's EGA card, the jumper is designated P1.
On the card shown at [here], the jumper is designated P6.

I have just been experimenting with an IBM 5154, and the subject jumper on my IBM EGA card.

If the jumper is in the wrong position for EGA (i.e. jumper is grounding pin 2), the DOS boot screen is still correct - white text on a black background. What would be incorrect is certain colours, those that use 'secondary red'.

But if I remove the jumper, simulating the jumper haven fallen off the card, the DOS boot screen becomes white text on a red background.

So, perhaps investigate the subject jumper on your EGA card. If present, it may need to be removed/refitted a few times in case of poor connection.

 

[marcampion]

thank you so much modem7! the card i’m using is actually an oak technologies oti 037c VGA. whenever i place the switches on the ega config 0-1-0-1, or the alternate 1-0-1-0 i get an image but it’s with the red background where there should be no color (black).

i don’t think this card has the jumpers you mention.
https://stason.org/TULARC/pc/graphi...LOGIES-INC-CGA-EGA-Monochrome-VGA-OAK-VG.html

 

[modem7]

i don’t think this card has the jumpers you mention.

Oh well.

the card i’m using is actually an oak technologies oti 037c VGA. whenever i place the switches on the ega config 0-1-0-1, or the alternate 1-0-1-0 i get an image but it’s with the red background where there should be no color (black).

I think it would be good for you to isolate the cause to either card or monitor. Can you borrow a known good card from someone else? If you tell us where you are, someone here may volunteer to test your card (at EGA) for you.

If you have an oscilloscope, a look at the red signals out of the 9-pin D connector would be revealing.

Have you tried flexing the video cable ?