View Full Version : Disable Sync on green on Twin Turbo

02-06-2002, 12:44 AM
Amazing info from Scott Harrison (http://www.macgurus.com/ubb/Forum2/HTML/000300.html):
There is a way to disable the dreaded 'Sync on green' option for some models of IMS/ixmicro Twin Turbo 128M-x via a jumper setting. For all of you that like to play Marathon 1-? at 640x480, this will make your day.

I thought that TwinTurbo comment might generate some interest. The card I have is a Twin Turbo128M4 (with 4 MB of on-board vram). A software check of the PCI card identified it as tt128m-C1. I have an old FAQ from ixMicro stating there are several other flavors of the Twin Turbo cards....the 128M2 and the 128MP2, both "with 2MB of on-board vram, which is upgradeable to 4 MB." They also had a 128M8 version with 8MB of on-board vram. Whether the following jumper setting info is applicable to all 4 versions or only the 128M4 is something I am not sure of.

Here is a quote I got directly from ixMicro when I was having trouble with my Apple 1710AV display with their card: "The TwinTurbo card is configured to use a feature called Synch on Green. Since the Apple 1710AV monitor does not require this feature, you must disable the Synch on Green jumper on the TwinTurbo card. To do this, changer jumper JP4 from position 2-3 to position 1-2." Those 1,2,3's refer to pins bridged by a single jumper at the JP4 pin set location....it came with the single jumper bridging pins 2 and 3. I moved that jumper to bridge pins 1 and 2, and the Synch on Green capability was thereafter hardware-disabled. The benefit was that on my 7500 with the TT card running a 1710AV monitor somehow the software setting in the ixMicro control panel was randomly getting lost and the thing would default to Synch on Green. I have never found an Apple monitor that needed S on G, and I have run alot of monitors from that card since.

Here is the JP4 and 1,2,3 pin secret information: Hold the card so the TT VLSI processor card is facing you, the two video-out connectors ("back" of card) facing to your left....Mac display connector will be on the bottom, smaller mini-D connector will be at the top. JP4 is at the bottom left corner of the circuit board, near the Mac display connector. Pin 3 is the top one, pin 2 is the middle, and pin 1 is the bottom of the vertically oriented set of three pins there. I knew there was a reason I saved all that stuff!

02-06-2002, 04:43 AM
Wow! Thanks MTR! I've always been plagued by that on both of my ixMicro cards. Couldn't present full screen movies in Quicktime either. Jumpers just never occur to us Macheads. http://macgurus.com/infopop/emoticons/icon_smile.gif

Scott Harrison
02-06-2002, 12:56 PM
The info on my card designation below ("tt128m-C1") has the C1 in there as the PCI slot it is in. I get name as IMS,tt128mb and model as tt128m when I probe it with Apple System Profiler 2.5.1

Two other ixMicro-provided Twin Turbo related quotes from my stash:

"The preferred display mode for QuickTime video playback is 16-bits per pixel" I wonder if this means that the TT hardware and software used with modern versions of QuickTime will work better with colors set to thousands rather than millions?

For you jumper lovers: "Question: What if I don't have video on my screen, how can I make it appear? Answer: .....Make sure there is no jumper across JP1. Try changing jumper JP4 from pins 2-3 to pins 1-2. Try removing jumper JP2. Check your board's ROM and make sure it is properly inserted into the socket." This would imply that you can get in there and dink around within these parameters without hurting things.