LM1881 with RGB - Audio noise on Display

[shift838]

I have a Myarc Geneve computer that outputs 15kHz signal. I have put together a simple circuit based on the LM1881 datasheet (it's exact).

I connect it all with my SCART cable but when the audio signals are going through the SCART cable I have quite a bit of signal interference on the monitor.

If I unhook the audio lines on the SCART cable it all looks great. How can I clean up the noise?

I am using a good SCART cable with great shielding already.

 

[maxtherabbit]

Use coax

 

[SiriusHardware]

In spite of what you say about shielding this sounds like crosstalk between the audio cables and video cables. When you say the cable is shielded, do you mean that the cable has an overall screen surrounding all wires, or do you mean that every one of the inner cables has its own individual screen?

On an overall screened cable the screen only stops the cables radiating to the outside world or picking up from the outside world, it does not prevent cross stalk between the individual cables inside. High quality screen cable specifically for SCART use has at least six individually screened cables in it, for R, G, B, composite video/sync and left and right audio.

As an experiment try running the audio signals from the Geneve to the monitor in separate twin screened cable and see if you still get the problem.

 

[shift838]

On top of the screen shielding that surrounds all the wires. All the R,G,B, sync and audio lines are shielded as well.

the link to the cable I have is:

HERE

 

[maxtherabbit]

Well it seems they aren't shielded enough then lol

This is not the first complaint I've heard of the kabeldirect scart cables. I strongly urge everyone to abandon scart completely and route audio and video separately, using 75 ohm coax for video lines