Neutrik HDMI feethrough problem

[Atohmdiy]

Hello,
Today i receive my mister case, i build it in a 1U enclosure. I use several neutrik pass-through for usb / eth / hdmi.
Everything seems to work fine except the hdmi out. I use my mister in direct video mode to feed a Tripp Lite hdmi to vga dac. It is working perfectly when the dac is directly connected to my mister, but it is not working when there is a neutrik NAHDMI-W-B in between. I don't think this is either the small hdmi patch cable i use (15 cm maybe) or the neutrik that have a problem, because i try 3 different of each and the problem is the same.

It is either not working at all, or the image is jumping. I thought it is a ground problem so i use a multimeter to test continuity. I tried different configuration by unplug / plug again the hdmi connector of the triplite to try to understand. Between the hdmi connector shell of the de-10 and the vga shell of the tripp lite, my multimeter either do not bip for continuity and give my 1500 ohm, or it bip. When it give 1500 ohm nothing i get no image, but when it bip for continuity i get an image, often unstable. But even when it bip and that the continuity is perfect and stable, i don't get stable image. What is most annoying is that sometime i got stable image, i play some games, no problem. I power down the de-10, remove the hdmi and put it again, and it doesn't work again.

I just don't understand, i think this is a problem related to the fact that the hdmi is not buffered as it is describe in a thread on the forum. Maybe is should buy an hdmi signal booster ?

Thank you

[jca]

It looks like you have 2 problems:
The sporadic connection between the shells and the unstable image when there is continuity. You have first to figure out what is the cause of the first problem and fix it. You should also insure that the HDMI connections do not exhibit a similar problem. Once you are sure that the connections are OK and if the image is still unstable you should get an HDMI repeater.

[Atohmdiy]

Hello,
I admit i never understood much with all these ground thing inside a case. I made some more investigation.

This is a photo of my build :

IMG-20200827-222949.jpg (2.92 MiB) Viewed 3679 times

When the dac is directly connected to the de-10, i check the continuity. The neutrik connectors on the front panel, the de-10 and blisster are in continuity, but not the neutrik hdmi out and the two connector next to it (ethernet and toslink) with a resistor of around 300 ohm. I think the problem come from here, but i don't know how to fix it.

[Atohmdiy]

The default of continuity come from the toslink connector, when remove it there isn't the 300 ohm resistance anymore. So in term of grounding it's now the same when i use the dac directly or with the neutrik passthrough.

Unfortunately it's not better because now i got no image at all. I really don't know what's going on, i don't see why a simple patch plus pass-through could fuck up the signal like this. My only bet is that to work the dac need to be directly connected as the de-10 hdmi is not buffered.

Edit : i also try without the direct video / composite sync mode, to a 1080p display. The pass-through works perfectly...

Edit 2 : i do another round of test. I try with another dac, a j-tech hdmi to vga that require external power to work, and it works fine too. So the problem is specific to the tripp lite dac that doesn't like when it's not directly connected. Any idea ?

[jca]

The default of continuity come from the toslink connector, when remove it there isn't the 300 ohm resistance anymore. So in term of grounding it's now the same when i use the dac directly or with the neutrik passthrough.

Toslink is an optical connection and should not have any effect on ground. Something is strange

Edit 2 : i do another round of test. I try with another dac, a j-tech hdmi to vga that require external power to work, and it works fine too. So the problem is specific to the tripp lite dac that doesn't like when it's not directly connected. Any idea ?

Are you using the power supply which came with the DE10-nano? When you tested the J-Tech did you use its own power supply? If so it could explain your problem as the standard PS can only deliverd 2A.

[Atohmdiy]

The default of continuity come from the toslink connector, when remove it there isn't the 300 ohm resistance anymore. So in term of grounding it's now the same when i use the dac directly or with the neutrik passthrough.

Toslink is an optical connection and should not have any effect on ground. Something is strange

Edit 2 : i do another round of test. I try with another dac, a j-tech hdmi to vga that require external power to work, and it works fine too. So the problem is specific to the tripp lite dac that doesn't like when it's not directly connected. Any idea ?

Are you using the power supply which came with the DE10-nano? When you tested the J-Tech did you use its own power supply? If so it could explain your problem as the standard PS can only deliverd 2A.

I don't talk of the connection by itself but simply the connector. I use the schematic i found in the io board v5.2, i have a 1uf connector between the +v and the grd. The toslink connector have a small metal shell that touch the naked part of the case, so it is surely grounded, and the 1uf cap surely do something here Before remove the toslink the parts (neutrik ethernet and hdmi) after the toslink connector have 300 ohm isolation, and after i remove the toslink there is no more resistance.

The trip lite use the power supply from the de-10, it has no connector for an external one. It is probably the problem, the extra cable and connector drop the voltage too hard for the dac to work propoerly. The J-Tech use an external power supply.

[jca]

I did not realize that you were talking about the components on the I/O board. It could be the capacitor, check it.
You need to upgrade your power supply: De10-nano + Memory + I/O board + USB hub board + USB devices and you are at the limit.
Somewhere in the forum there are references to good power supplies or check with MISTer vendors.
Good luck.

[Atohmdiy]

In fact i don't use much of the io board, and it's a v6, the capacito is directly solder to the toslink connector. And for the power supply i already use a 4A mean well, hard to have better.

[jca]

I guess you will have to use the J-Tech as the 4A supply is more than enough.