5170 occasionally boots with no color?

[acenewman]

Have noticed that my 5170 will now occasionally boots up and have no color, just black and shades of gray. Curious if anyone has run into this before? Looking for recommendations on where to start troubleshooting. Usually if I just reboot the machine it comes back with color. Thanks, Chris

 

[Eudimorphodon]

Does it have a VGA card?

Old VGA cards assigned some pins on the connector to detect if a mono or color monitor is detected. Those pins were reassigned for different purposes in the 1990’s, if you have a newer monitor connected to a sufficiently ancient VGA card it may once in a while get confused. (Specifically, pin 12 is now used for an I2C communication channel, but back in the day it being grounded meant “mono”.)

 

[acenewman]

I am running a 256K Trident video card and using a Zenith Data Systems monitor. I will have to make better notes of the frequency. Seems like it didn't happen at all for the first few months after I got the computer up and running. Seems like the frequency of the events was increasing and that is what caught my attention. Thought it might be an indication of a component heading south.

 

[rvdbijl]

Does it have a VGA card?

Old VGA cards assigned some pins on the connector to detect if a mono or color monitor is detected. Those pins were reassigned for different purposes in the 1990’s, if you have a newer monitor connected to a sufficiently ancient VGA card it may once in a while get confused. (Specifically, pin 12 is now used for an I2C communication channel, but back in the day it being grounded meant “mono”.)

Hmm... I guess that’s why my PS/2 machines don’t like my KVM to be in color. So perhaps disconnecting pin 12 should do it? I’ll have to give that a try. Thanks!

 

[Eudimorphodon]

Hmm... I guess that’s why my PS/2 machines don’t like my KVM to be in color. So perhaps disconnecting pin 12 should do it? I’ll have to give that a try. Thanks!

I'm reasonably sure that pin 12 n/c is the valid/correct config for a color monitor attached to a VGA card old enough to use the old ID sense line layout, so pulling pin 12 out of the end of the cable you connect to the PS/2 should be fine. But my memory could be rusty. All my working retro-computers either pre-or-post-date this era of VGA, oddly enough.

 

[rvdbijl]

I'm reasonably sure that pin 12 n/c is the valid/correct config for a color monitor attached to a VGA card old enough to use the old ID sense line layout, so pulling pin 12 out of the end of the cable you connect to the PS/2 should be fine. But my memory could be rusty. All my working retro-computers either pre-or-post-date this era of VGA, oddly enough.

Just tried it today with a VGA "extension" cord. I didn't want to yank pins out of my expensive and hard to find KVM cable. No dice though! I was fully expecting this to work, but it doesn't -- during bootup, my Model 80 (with 8514 board) spits out blue text. Once DOS boots, it's white, but the system will not output color from that moment further. I wonder if I need to ground pin 11 perhaps to ensure it's not thinking that there is no monitor connected. Haven't tried my PS/2 model 30 yet, but that one hasn't had any issues with color output, just its default is grayscale with the KVM connected....