Hum from HDMI

[Jeff Romard]

So I'm back to the club for a 6-10 deal tonight I went out yesterday to run the HDMI cables to the new TV's and I started getting a buzz through the sound system. First thing I thought was the splitter was causing it so I pulled out the connector to the computer the buzz went away. I tried each cable individually and every one caused a buzz. I haven't tried a second laptop yet but I assume this is working it was 3 months ago when I last used it.

Any ideas?

 

[steve149]

Are you running the HDMI cables near power sources? Is the splitter passive or active .. and if active, is it on the same circuit as the laptop?

 

[Handinon]

to the new TV's

I'd start right there. Take your volt meter and measure the AC voltage from ground on the TV (with it on but no HDMI cable connected) to the ground on the AC outlet. Then reverse the plug and read it again - use a cheater if you have to, since the plug might be polarized with one larger spade. Do this for both TV's and leave them plugged in the way that gives the lowest reading. If the TV's are encased in plastic, use the coax antenna connector's outer part for the TV's ground point.

 

[sawdust123]

You are creating a complex grounding situation when you combine multiple TVs (probably plugged into different outlets) and a sound system (plugged into another outlet). The HDMI cable to your computer is the last link in that chain and completes the ground loop. A fiber based HDMI cable may solve the problem for good but they can be expensive. A heavy ground bond between offending components could remove most of the ground current from your signal conductor. A 12 AWG speaker cable can act as that bond. You have to experiment. Bill Whitlock (formerly of Jensen Transformers) has some good troubleshooting tips you can try. You can find them in a search.

 

[Jeff Romard]

Are you running the HDMI cables near power sources? Is the splitter passive or active .. and if active, is it on the same circuit as the laptop?

Yes Active and yes. I did try moving the laptop to another circuit still seems to be a problem

I'd start right there. Take your volt meter and measure the AC voltage from ground on the TV (with it on but no HDMI cable connected) to the ground on the AC outlet. Then reverse the plug and read it again - use a cheater if you have to, since the plug might be polarized with one larger spade. Do this for both TV's and leave them plugged in the way that gives the lowest reading. If the TV's are encased in plastic, use the coax antenna connector's outer part for the TV's ground point.

Thanks I will try that but I don't think that's the problem because I individually checked the cables and even the old ones are buzzing when they hit the port now

You are creating a complex grounding situation when you combine multiple TVs (probably plugged into different outlets) and a sound system (plugged into another outlet). The HDMI cable to your computer is the last link in that chain and completes the ground loop. A fiber based HDMI cable may solve the problem for good but they can be expensive. A heavy ground bond between offending components could remove most of the ground current from your signal conductor. A 12 AWG speaker cable can act as that bond. You have to experiment. Bill Whitlock (formerly of Jensen Transformers) has some good troubleshooting tips you can try. You can find them in a search.

Thanks Jon I'll do some reading

 

[Proformance]

You are creating a complex grounding situation ...

Yeah, you've simply created a ground loop (and probably more than one.)
The fact that HDMI carries digital signals does not mean it is electrically isolated. The cable is still a conductive path for voltage differentials.

Do you need a permanent solution (one that resolves this everywhere you might play) or a temporary/specific solution for just this venue ?

Are there coax (analog unbalanced) connections to these TVs from other devices like DVD players, cable boxes etc (RCA, F, TS?) Try disconnecting these other inputs while using your HDMI link.