I recently stuck an E-Machines Double Color LX video card in my Mac IIfx, cabled through a VGA adaptor to a 17 in Sylvania CRT monitor. Works fine, but all resolutions except 640x480 have a green background..doesn't really hurt readability but is annoying. Is this the sync on green problem or something else?
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Green background on monitor
- Thread starter mac2geezer
- Start date
Sync-on-green usually gives an overall green hue/tint to the picture. If only the background is appearing greenish (as in the grey desktop background) it is possibly just poor definition on the monitor with all those little black & white dots. Try bringing the screen resolution down and see if that cures it, or edit the desktop pattern and set it to all white or all black and see if that effects it.
Try cleaning all male connectors in your video data chain -- alcohol, methelated spirits, electrical contact cleaner will all work. Use an old toothbrush to get at the pins.
If that fails try a different Mac-->VGA converter. Or if the VGA monitor cable is swapable, try one with better shielding. Thicker diameter cable (external diameter) usually means better internal shielding.
If that fails try a different Mac-->VGA converter. Or if the VGA monitor cable is swapable, try one with better shielding. Thicker diameter cable (external diameter) usually means better internal shielding.
Thanks to all for the replies. The green tint is there at all resolutions...640x480,832x624,1024x768...and changing to black and white makes no difference, nor does editing the desktop background pattern. I will try cleaning all connectors, but unfortunately the video cable is hard wired to the monitor and I only have the one Mac-VGA adaptor.
As I said, readability doesn't suffer, it's just annoying, but since the monitor was cheap (ie, free) I'll not complain too much.
As I said, readability doesn't suffer, it's just annoying, but since the monitor was cheap (ie, free) I'll not complain too much.
if it's definitely only the background and has perfectly white windows and menus then it's got me stumped. However, E-Machines were a branch of Radius and I know practically all Radius and Supermac NuBus video cards use SoG.
Most NuBus video cards do separate sync (the best solution for analogue video) by preference, falling back to combined sync or sync on green, depending on the capabilities of the monitor. Most monitors use separate sync or combined sync, hence the requirement for those special adapters for the IIci built-in video etc.
In my experience using Radius Thunder cards and SuperMac cards they actively use Sync-on-Green. In fact the Thunder cards only support 2 resolutions out of the 20-odd they provide in Separate Sync mode. Off the top of my head they are 1024x768 and 640x480, I think.
It's not just the background; the windows and menus have a slight green tint also. So I guess that means it's the sync-on-green problem, even though I'm not sure of the exact details of that. If someone wants to give me a short tutorial it woud be greatly appreciated.
WIthout a photo, it's hard to say too much for certain. Your problem could be caused by many things, including a weakened crt. The red gun often weakens first, because it's driven the hardest (because the human eye is not sensitive there, and red crt phosphors tend to be of low emissivity, the red gun is typically cranked up pretty high, leading to somewhat faster wearout).
If you eventually determine that a weak red gun is the problem, here's what to try: Inside the monitor are several adjustments for settng beam currents. If you're lucky, they're labeled (in many, even the potentiometer shafts are helpfully color-coded). First note or mark their initial positions. Then crank up the red and/or blue one (or crank down the green one; or do both). If you're lucky, you'll be able to get a decent white balance without degraded focus.
If you eventually determine that a weak red gun is the problem, here's what to try: Inside the monitor are several adjustments for settng beam currents. If you're lucky, they're labeled (in many, even the potentiometer shafts are helpfully color-coded). First note or mark their initial positions. Then crank up the red and/or blue one (or crank down the green one; or do both). If you're lucky, you'll be able to get a decent white balance without degraded focus.
The monitor came from a Windows system where it showed none of the green tint problem, but one of these days I may open up the case and try the tweaks. Trying to set the color balance via the on screen controls doesn't fix the problem, so not sure tweaking the internal pots will help. It's definitely a low priority around here; it's just a second monitor on the IIfx.
