HDMI-SDI -HDMI can not work

I connected my PC to a HDMI-SDI converter(Teranex Mini) via HDMI cable, and then a SDI -HDMI converter(Teranex Mini) was connected via SDI cable. Finally a monitor was connected to the end. So the data was transmitted from PC to converters and finally to the monitor. But there was no image on the monitor? I don't know why it didn't work. Anyone has ideas?

Constructing a block diagram in my head, here....

PC HDMI "Out" connected to Teranex Mini to output SDI... then re-converting from SDI to HDMI via another Teranex Mini to display HDMI output on a ... consumer monitor/TV set? or another computer display? or...?

Why would you not directly connect the computer HDMI directly to your target monitor?

I do not understand this double conversion process. Are you attempting to re-scale the resolution? frame rate? something else?

Are you attempting to pass UHD through a non-dual-link or non HDCP compliant cable? Are your HDMI cables unidirectional?

Enquiring minds need to know.

jPo, CSI

BM devices don't even touch HDCP (neither typical signal out of GPU in PC).

[Gary Adams]

Hello Peter. Having more information here might help. If your Teranex Mini Converters have the front panel display, do you see the image on either of them? If so, do they display the resolution and rate? What resolution and frame rate do you have the Computer extended desktop set at? Mac or PC? Note the Mini converters only work at Broadcast resolutions and frame rates.

Regards, Gary

Thank you for your reply.
I need to process the HDMI output data before sending it to another moniter. Since it is easier to handle the SDI format signal, I use two converters. But it can not work just connecting these devices(haven't added the signal processing unit to this link yet). I have tried three types of minitors. For the TV set(2160P@30Hz), it works. But for the other two special dispalys(2160P@60Hz,1080P@90Hz), It can not work. The Teranex Mini supports Ultra HD formats up to 2160p60, and the HDMI and SDI cables are normal cables. I am not sure whether these cables are non-dual-link or non HDCP compliant. For the special dispaly(1080P@90Hz), maybe the converter can't support the resolution at this frame rate. But for the other dispaly(2160P@60Hz), I don't know why it can't work.

Hello Peter. Having more information here might help. If your Teranex Mini Converters have the front panel display, do you see the image on either of them? If so, do they display the resolution and rate? What resolution and frame rate do you have the Computer extended desktop set at? Mac or PC? Note the Mini converters only work at Broadcast resolutions and frame rates.

Regards, Gary

Hello Gary.Thank you for your reply.
There is no front panel display on my Teranex Mini converter. But I can set the resolution and frame rate via PC. The resolution of my computer desktop is 2160P@30Hz, and the converter supports the resolution up to 2160P@60Hz. It works with TV set(2160P@30Hz), but it can not work with a special display(2160P@60Hz). Sometimes when setting the converter to the resolution of 1080P@60Hz, there was a blurred screen with the pecial display(2160P@60Hz), and sometimes there was no image at all.I don't know why.

BM devices don't even touch HDCP (neither typical signal out of GPU in PC).

Thank you for your reply!
Do you mean it is nothing to do with the HDCP? But to the contrary I think maybe it is caused by the HDCP. Without the converters it works well for any kinds of monitors.

BM devices have issues with its HDMI output. This has been reported countless times.
You may have some other incompatibility issue with HDMI 2.0. Does your monitor support HDMI 2.0 or is it based on HDMI 1.4 chip with "hacked" 4:2:0 mode for handling UHD 60p?

Try forcing Teranex specifically to output YUV or RGB (4:4:4) and check then with your monitor. Maybe your monitor works only with RGB HDMI signal. For UHD 60p Teranex most likely sends YUV 4:2:2 (not sure if RGB can be forced on HDMI for UHD 60p).

HDCP is used only with things which need to send protected signal, like Blu-ray players etc. BM devices don't use HDCP. HDCP is an optional HDMI feature. I've never heard of non HDCP compliant HDMI cable. If you have something "average" (not very cheap crap) then it should work. You can easily eliminate cable, by trying different one (best if it's different brand to current one).

HD at 90Hz is most likely not going to be supported by Teranex.

BM devices have issues with its HDMI output. This has been reported countless times.
You may have some other incompatibility issue with HDMI 2.0. Does your monitor support HDMI 2.0 or is it based on HDMI 1.4 chip with "hacked" 4:2:0 mode for handling UHD 60p?

Thank you for your information.
I guess the special dispaly only supports HDMI 1.4b while my PC video card supports HDMI 2.0. I have tried to force Teranex to output YUV or RGB, but it still didn't work. When I connect the PC and monitor with converters, it says that the monitor doesn't support the HDCP. However, without converters it works and shows that the monitor supports the HDCP.

UHD 60p won't "normally" work on HDMI 1.4 chip. There is only one special/hacked mode using 4:2:0 sampling which makes it working, but this is "special" case. If UHD 30p works, but 60p doesn't it simply means your monitor is not supporting UHD 60p or at least not using standard HDMI 2.0 modes.

UHD 60p won't "normally" work on HDMI 1.4 chip. There is only one special/hacked mode using 4:2:0 sampling which makes it working, but this is "special" case. If UHD 30p works, but 60p doesn't it simply means your monitor is not supporting UHD 60p or at least not using standard HDMI 2.0 modes.

I've tried but neither UHD 30p nor UHD 60p works. However, without connecters, just connecting PC and monitor directly, it works well. I don't know why.

Anyone has new ideas?