Blackmagic Forum

Hi - I've used BMD HDMI-SDI convert pairs for years with no problems. But in a new installation, my screens are randomly going blank.

The setup -
- two Mac Studio M2's with direct connected HDMI monitors.
- six Black Magic HDMI-SDI Micro converters pairs (three per computer).
-- Four new G3 converters and two original converters.
- six 70' 4k LED screens (Sony and Insignia, three per computer).
- brand new 3G/6G Belden 1694A/Canare BNC cable runs of 100' (three) and 200' (three).

The Symptoms -
Everything boots up fine and I see desktop images on all six screens. Within approx 10 minutes one of the screens will go blank without displaying a "lost connection" message. The image can be restored to the screen by unplugging/replugging the thunderbolt adapter at the computer. Other details -

- It is never the same screen(s) that goes blank or the same pattern.
- Multiple screens never go blank at the same time. One might blank after 5 minutes and then another after 3 more minutes.
- It happens both on the Sony and Insigina displays
- Screens from both computers have randomly gone blank.
- It happens on both the 100' or 200' cable runs
- Never more than 3 screens have gone blank at a time and never all of the screens from one computer.
- Screensaver and power saver settings are off on both computers
- Remote desktop into the macs show the blank screen desktops as active.
- The direct connected HDMI computer display never goes blank.
- When the thunderbolt/HDMI adapter is unplugged from the computer, the screen shows "lost connection"
- When the thunderbolt/HDMI adapter is replugged into the computer, the desktop image comes back

Any ideas? Thanks!

Hello! Have you ever solved this issue? I'm experiencing this too.

The issue was resolved by switching to Apple-brand Thunderbolt-HDMI adapters. When using Anker or other brands the HDMI license handshake was somehow messing up randomly after a few minutes.

It seems that sometimes large screens or beamers do not like the HDMI signal coming out of the BMD SDI->HDMI converters. The screen just randomly blacks out for a short while. My go to solution is then to swap them out for a Decimator Design MD-LX or MD-HX device and the problem is solved. I guess it's a (design) bug in the converters.

patnims wrote:The setup -
- two Mac Studio M2's with direct connected HDMI monitors.
- six Black Magic HDMI-SDI Micro converters pairs (three per computer).
-- Four new G3 converters and two original converters.
- six 70' 4k LED screens (Sony and Insignia, three per computer).
- brand new 3G/6G Belden 1694A/Canare BNC cable runs of 100' (three) and 200' (three).

That list looks like converter city. If you've HDMI at the source and are using projectors or screens with HDMI capability, dispense with all the converters, power supplies and expensive Belden SDI, and use fibre HDMI. You will have a perfectly stable image and you can run up to 150 metres with off-the-shelf fibre HDMI from Amazon.

We typically use 50-100 metre heavy-duty material-braided fibre HDMI for both projection and LED screens and never had one fail on a show yet. We even use them for triple-blend projection screens, where sync-timing needs to be perfect.