NVIDIA 3D Vision Pro and VESA Stereo Sync

We ran into problems recently getting the NVIDIA 3D Vision Pro glasses to work on a dual-pipe stereo projector (clone mode stereo). The projector takes two DVI inputs, one for the left and one for the right eye at 1920×1080 and 60Hz. These are then displayed frame sequentially at 120Hz. The projector has the standard BNC connector which outputs the stereo sync signal for the glasses (Sync and Ground).

The NVIDIA RF base station (pyramid) has a 2.5mm stereo jack socket which accepts external stereo sync, so we tried feeding the projector sync into that input. Unfortunately, the pyramid seemed to ignore the external sync and wouldn’t activate the glasses…

We had the NVIDIA pyramid working well on another system in active stereo, using the 3-pin VESA sync output from the graphics card, so I decided to test that. This is what I found:

  • When running at 120Hz active stereo, the Sync signal is a simple 5V square wave with 50% duty cycle of around 8.33ms high and 8.33ms low, exactly as you would expect.
  • The LED on the back of the pyramid lights up blue when it’s using external sync, green otherwise.
  • When using active stereo, the Sync light only illuminates when stereo is activated (i.e. when running a stereo application)
  • 5V power is always present on the 3-pin VESA stereo connector.
  • If the 5V power is removed, it ignores the external SYNC input. Using only SYNC and GND is not enough to get it working.
  • Once it has switched on and started accepting external Sync, I tried disconnecting the 5V power: the blue LED stayed lit. This suggests it only checks for presence of 5V at start up.

This is what the Sync LED looks like when the unit is persuaded to accept external sync:

NVIDIA 3D Vision Pro Pyramid

The solution was to make a cable which combines the Sync output from the projector with 5V (taken from USB) and Ground onto a standard 3-pin mini DIN VESA stereo connector (pinout shown below). The picture above shows the cable (white Y-shaped cable) taking Sync via a BNC connector (the T-piece is used to connect another IR emitter in parallel) and the connectors on the right are the 3-pin mini DIN stereo cable, which goes to the 2.5mm jack sync input on the NVIDIA pyramid.

This is the pinout of the VESA Stereo 3-pin mini-DIN socket:

 VESA Stereo 3-pin DIN

 And here’s the corresponding pinout for the NVIDA 3D sync jack:

NVIDIA 3D Sync Jack Plug

Caution: the jack plug isn’t a great choice of connector for something carrying GND and 5V, as there is obvious potential for a temporary short when the plug slides in and out of the socket. Avoid connecting/disconnecting the jack when the system is powered up. It’s safer to disconnect the USB and mini-DIN plugs.

14 thoughts on “NVIDIA 3D Vision Pro and VESA Stereo Sync”

    1. Hello Emmanuel
      Yes, that would work. Any +5V supply would work providing it has a common GND with the equipment supplying the SYNC signal. The 5V normally comes from the 3-pin VESA connector, but you can substitute a different 5V supply if you don’t have VESA. Our projector only had BNC sync output (just SYNC and GND) and no VESA 3-pin output.
      Hope this helps?

    1. Hello Alejandro
      The jack plug on the NVIDIA pyramid is the smaller 2.5mm jack (not the 3.5mm headphone jack size).
      I made my own cable to do this. It’s the white cable in the photograph which splits into two. I bought a 3-pin female mini DIN socket, and cut up an existing USB cable and BNC cable, then soldered the Ground and +5V connections from the USB cable to the mini DIN, and the Ground and Sync connections from the BNC to the same mini DIN, then insulated with heat-shrink tubing. Then I connected the 3-pin female mini DIN socket to the 3-pin male connector from the NVIDIA cable (i.e. used the NVIDIA cable to convert 2.5mm jack to 3-pin mini DIN, then my own cable to convert this to BNC).
      You could also buy a 2.5mm jack plug and BNC cable and make a cable to go direct from the pyramid to BNC, although you would also need to put the 5V signal on the correct jack pin. The pinout diagrams are above.
      I’m not aware of a standard “off the shelf” cable to do this, I think you might need to make your own as I did.

      1. Thanks for the quick replay, I have 2 projectors Mirage hd6k blend together, i have a Quadro k6000 with the stereo bracket, I have lost the cable 3pin mini din to BNC, so I cant sync my projectors, I made I wire from 3 pin mi din to RCA the I put a BCN converter with out the 5v , the cable work for little while then stop working, so the BNC you use has external power?

        1. If you are using a K6000 with the stereo bracket that has the 3-pin mini DIN VESA stereo socket, then you do not need 5V. The 3-pin socket on the stereo bracket has 3-pins: GROUND, 5V (output), and SYNC (output). The BNC connector should be wired to the GROUND (barrel of the BNC connector) and SYNC pins (centre pin of the BNC connector) only. You should leave the 5V pin on the VESA connector disconnected in this case.
          How is the sync wired to the projectors and/or emitters?

          1. Thanks the wires are like this I have the in the WS the Quadro k6000 connected to the stereo bracket them for it one cable (3 pin mindin to BNC) connect to a T connector that split in to 2 BNC to the projectors to GPIO ( has 3 BNC convectors 2 inputs 1 output) cable the input a the emitter connect the projectors to GPIO out put, bests regards

          2. Have you got a multimeter? You could check your cable with the meter to make sure you have good continuity, in case a wire has come adrift, or you have a short. The 3-pin mini DIN connectors are very tiny, and I would recommend insulating the connections with heat-shrink tubing to make sure they can’t short.

            If I remember rightly, you might not even need to send the SYNC through the projector, it could probably go direct to the emitter. Although the projector sometimes inverts the SYNC before sending it to the emitter, if you need to invert the SYNC it is also possible to do this in the NVIDIA Control Panel.

  1. Hi,

    I have a Christie HD6 projector and it has a GPIO (db9) output connector. Pin 4 of the GPIO is 3D Sync output and pin 5 is ground.

    The projector can generate 3D sync signal on pin 4 and I measured the output and it only outputs about 1.6v…

    I brought a 2.5mm audio jack. I cut the USB cable. There are 2 data cables and I leave them untouched. Then I soldered the 5v and ground to the 2.5mm audio jack. I also soldered Pin 4 and pin 5 to the 2.5mm audio jack. Pin 4 to the tip(3d sync) and pin 5 to the ground.

    I connect the 2.5mm audio jack to the emitter. Then I plug the USB cable into my pc and the IR emitter. The green led lights up. It seems that the emitter ignores the external 3D signal from the projector.

    So, I am not sure what is wrong with my setup. Is it because the 3d output signal is only 1.6v?

  2. Hi Mac

    Looking at the Christie documentation, it looks like the GPIO pins use 3.3V logic levels. Are you measuring the output with a multimeter or an oscilloscope?

    If you use a multimeter, you will see a lower voltage, because it will effectively be a kind of “average” of the 50% duty cycle of the sync signal. For example, 3.3V * 50% duty cycle = 1.65V, which is what you seem to be measuring?

    The VESA sync signal is normally 5V, so perhaps it is too low to trigger the emitter (although this is a little surprising, as I would have thought 3.3V logic would be enough to trigger it).

    If that is the issue, you could use a level shifter to convert 3.3V to 5V of course. There are several ways to do this (can be achieved with a transistor and a couple of resistors, or with a buffer IC, or there are ready made PCBs you can buy for a simple solution).


  3. soo i have an projector emitting an 5v activation signal and 3.3v sync signal and the emitter isnt activating. Does it need connection to computer for engaging? like it needs an software signal first since my projector is showing correct picture, i have an oscilloscope but not an fucntin generator.

    1. Hi there
      Yes, if I remember rightly, the NVIDIA pyramid does require a USB connection to the PC in addition to needing both SYNC and 5V on the mini jack plug. I don’t think it will work with the mini jack alone. The driver initialises the emitter over USB, before it starts looking for external sync.
      For a completely stand alone emitter that doesn’t need a USB connection to the PC, you would need to look at an alternative setup like the XPAND or Volfoni glasses.

    1. Hi, I’ve only used this with “3D Vision Pro”, so I’m not sure whether or not this is supported by the “consumer” version of 3D Vision.

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