Green Tint on VGA CRT Monitor Connected to Macintosh IIx

[_nec6678]

I just picked up a Gateway CRT monitor along with a Pentium 4 Gateway tower PC for four dollars total. I also got a NAD MR13 for free with no vertical deflection that I need to repair, along with a neat IBM PS/2 keyboard that was two dollars. The Gateway PC turns on for only a split second before it shuts off, but I suspect the crappy old power supply to be the issue.
When I first turned on the Gateway monitor, it displayed a floating test pattern saying my monitor was in working condition. However, there were loud clicks accompanied by the picture flickering, so I took it apart. The first thing I did was reflow the solder around the flyback and on the neck, and did a quick test. However, there was still the dreaded click, so I took off the anode cap, cleaned it with isopropyl alcohol, applied (a little to much) dielectric grease, and put it back on. I put the monitor fully back together because I knew that there wouldn't be much that I could do with the click other than that. When I turned the monitor on, the click seemed to be gone until it clicked again! After using it for a while, however, the click eventually went away.
However, the remaining issue is with a green tint on the picture when the monitor is connected to my IIx. I have an Apple DB-15 to VGA adapter that worked with a flatscreen Dell

 

[ClassicHasClass]

This sounds like a sync-on-green signal which your monitor doesn't know how to filter. There are circuits that will remove this. Myself I use an active sync-on-green converter that turns it into more typical composite sync, though these are not cheap.

Alternatively, you could try fiddling with the adapter if it has DIP switches, or you could use a different Mac video card that doesn't emit (or solely emit) S-o-G if you have one.

 

[_nec6678]

This sounds like a sync-on-green signal which your monitor doesn't know how to filter. There are circuits that will remove this. Myself I use an active sync-on-green converter that turns it into more typical composite sync, though these are not cheap.

Alternatively, you could try fiddling with the adapter if it has DIP switches, or you could use a different Mac video card that doesn't emit (or solely emit) S-o-G if you have one.

Unfortunately, my adapter doesn't have any DIP switches. Do you have any recommendations for a specific sync-on-green converter?

 

[ClassicHasClass]

The one I use is a Software Integrators #7053. They still sell these, but they are not cheap, about $140 ( https://si87.com/Shops/3738123e-8b74-40b2-bd96-ddff0f19d352/Products/7053 ). They require an active 6V power supply which is included, and work for most systems and monitors. You plug the output of your Mac adapter into the input and your monitor into the output.

 

[_nec6678]

Ah, that is just a bit over my budget for this! However, would the "Mac Sync-inator" I found on BMOW work for this?

 

[ClassicHasClass]

I'm not sure, but my suspicion is no, based on this paragraph (bold at the end mine):

The image’s colors look pale or faded
This may happen when the computer’s video signal contains sync-on-green, and the monitor misinterprets it as color information. Try changing the computer’s gamma settings to help compensate: In the Mac’s Monitors control panel, hold the Option key while clicking the “Options…” button to show the gamma settings. Sync-on-green is an analog signal mixed directly into the RGB color signals, unlike the separate composite sync and horizontal/vertical sync signals that the Sync-inator operates on. If gamma correction isn’t enough, try using a different monitor or a specialized video signal processor that can perform analog sync stripping.

This seems like the situation you are experiencing, and that last sentence implies that this adapter does not do the kind of sync filtering that the #7053 box does. Steve makes good stuff and this device might still be worth getting because it will give you a lot more configuration options, but I don't think it will solve this particular problem.

 

[_nec6678]

Unfortunately, adjusting the gamma does not fix that much for me. There are only two options for gamma: Mac II Std Gamma and Uncorrected Gamma, and it doesn't change when I hold down the option key and click on Options.... Even though it doesn't really look like it through the camera, selecting Uncorrected Gamma makes the green deeper, and selecting Mac II Std Gamma makes the picture a somewhat less saturated shade of green. So far, I have been able to get around the issue for the most part by turning down the green all the way in the monitor settings, but the color still looks off.

 

[_nec6678]

I actually just remembered that I have this thing, a Communications Specialties Inc. Scan Do Pro, that looks like it might be able to do the job. I'll have to try it out and see if I can get it working!