I purchased my Oculus Rift headset back in July 2016 and since then it has had a lot of use. Last month I started to get an intermittent issue with the HDMI disconnecting.
I assumed that it was the headset cable and so I contacted Oculus support who told me that the cables are no longer being supplied or sold unless the headset was under warranty.
I tried a different HDMI extension cable on my Rift headset and the issue was resolved so it was a problem with the extension but as I knew that other people had problems with their cables it was only a matter of time before mine failed, rendering the VR kit worthless and junk as Oculus have chosen not to support first generation VR headset users.
I found a lot of other people who had the same headset cable issues and who are unable to get a replacement cable and so I decided to order a faulty cable from eBay to see if it is possible to repair them to give me a spare cable for the future.
The faulty cable arrived from eBay and it had several large kinks and flattened areas in its length. I connected the cable to my Oculus Rift headset and starting at the headset end of the cable, moved the cable around bending it in all directions to find the section which had a fault.
The fault was tracked down to a section around 20cm from the headset connector end and after removing the outer plastic covering and separating the wires we reconnected it to the headset and wiggled each of the exposed wires to try to recreate the blank headset problem.
Inside the outer cable covering is a metal braid and shield which contains the following:
2 x USB cables, twisted pair which are green and white.
5 x shielded twisted pairs for HDMI channels with ground wire and shield in each.
5 small cables.
4 larger cables.
The Problem Wire(s)
The issue was tracked down to an intermittent connection on what appeared to be a small red/silver cable and after inspection under the microscope it turned out to be a twin pair twisted cable with a metal shield and foil covering which appears to be one of the HDMI channels.
Using photos taken under the microscope at 20x magnification next to a known size component (0805 resistor), I was able to approximate the cable size to be:
Outer shielded sheath 0.8mm diameter.
Twisted pair inner cable 0.3mm diameter.
Twisted pair inner cable core: 0.12mm diameter.
As these are much too small for me to solder by hand and keep the tight twists in the pair of cables, I was not able to proceed any further with repairing the cable and so we decided to take the headset connector apart to see what is inside and if it would be possible to source a replacement.
Removing the plastic covering revealed a shielded metal enclosure.
Lifting the metal cover revealed a small circuit board with a second plastic cover and the cable connections sealed in a clear potting compound.
The photo below shows the very small twisted pair HDMI cables with their three connections onto the connector.
Under the other side of the connector was a very small circuit.
The integrated circuits are marked as:
This is a VR7050 USB 3.0 In-Cable Equalizer from www.spectra7.com/vr7050
This seems to be a older chip dating back to 2012 from this press release: https://www.spectra7.com/pdfs/VR7100_PressRelease_Rev_2.2.pdf which states:
“The VR7100 features patented chip technology which is optimized to deliver the video bandwidth required for a fully immersive, stereoscopic 3D experience. The chip leverages Spectra7’s patented power harvesting algorithms, eliminating the need for any external power source while delivering up to Ultra HD 4K resolution. The VR7100 is available in a miniature, ultra-low profile QFN package measuring 5mm x 5mm.”
As is it not possible to repair this cable or replace the connector due to the proprietary connector and cable, I will have to replace my entire Oculus Rift VR system when my cable finally breaks.
After looking at the current Oculus models, I think it maybe time to ditch the platform and go to the HTC Vive Pro with its two lighthouse transmitters to be installed in the room.
Update: 19th Sept.
After posting a link to this post on Reddit there were numerous comments regarding my soldering skills and how easy it would be to connect wires with a thickness the same as a human hair (0.08 – 0.1mm width).
Soldering the actual cables together wouldn’t be too much of an issue with the fine tip irons we use but the problem would be insulating the twisted pair cables and maintaining the twists thought out the length of the repairs.
With twisted pair cables, having a straight section without the twists would cause problems with the signal integrity and can introduce interference with the HDMI data rendering the repair useless.