video interference

[666damned]

hi guys..just fitted a nice new 9inch screen itno the car.but getting terrible 'flickering' when engine is running,but stops when engine is off....guess i'm picking up interference up from something.....is there anything i can do/purchase to cure this?


rgrds....dave

[Nick Mann]

I know it can happen with sound, so I guess it can happen with pictures too? For radios you can buy something like this: http://www.quasarelectronics.com/sma...suppressor.htm No idea if that is good for your problem too or not.

[apeman69]

Is this a replacement screen? If so and you're using the same input cable (e.g. VGA) and the old screen had no interference then it will be the screen's power connections or the screen itself. If it's plugged into the lighter socket there's a reasonable chance of signal noise.
If you know certain components of the system are good then remove the new stuff and test each new component with known working bits until you isolate the problem.
All components of the system should be grounded at the same point e.g. amps, pc, screen to minimise the possibility of ground loop interference.
More detailed info will allow someone to advise more specifically.

Sent from my Huge Brain using MyFingers

[Turbo_Steve]

Agree with the above. Make sure you have a decent quality earth into the cabin from the battery -ve.

Make sure all your audio/video toys are bonded to that earth.

If you're driving your digital screen via VGA, you should try and use the LOWEST clock frequency possible (i.e. 50Hz or 43Hz) and NOT the highest: this provides better noise immunity.
You may need to knock up a custom VGA cable that "de-couples" the earths. The same is true of composite and component video.

[666damned]

Agree with the above. Make sure you have a decent quality earth into the cabin from the battery -ve.

Make sure all your audio/video toys are bonded to that earth.

If you're driving your digital screen via VGA, you should try and use the LOWEST clock frequency possible (i.e. 50Hz or 43Hz) and NOT the highest: this provides better noise immunity.
You may need to knock up a custom VGA cable that "de-couples" the earths. The same is true of composite and component video.

cheers steve....completely bafled me now.......pmsl..........thanx for all your info guys,it's a stand alone monitor running from my dvd h/unit.....using same switched live and earths as h/unit...had another play today,and is now not displaying the picture at all...although it is powering up fine ...tested a few other video cables to see if that was the cause....but no success...now suspect output from h/unit.....

[orionn2o]

Could also be Electromagnetic interference from running the cables past an electrically noisey device.

Easy things to check.

1) Direction of cables from headunit to screen. If you just run them direct or move the cables, does the interference change?
2) It could be a noisey voltage input - the dvd player will have a filter built in. Does your screen have a decent filter in-line on the cable??
3) Ground loops, unplug the signal input and power the screen, start the engine. Do you still get flicker? If you dont then its possibly from your signal cable, if you do then its power filtering.

You can buy a 12v switching psu for ICE and these will filter input noise which could be an option???

[666damned]

Could also be Electromagnetic interference from running the cables past an electrically noisey device.

Easy things to check.

1) Direction of cables from headunit to screen. If you just run them direct or move the cables, does the interference change?
2) It could be a noisey voltage input - the dvd player will have a filter built in. Does your screen have a decent filter in-line on the cable??
3) Ground loops, unplug the signal input and power the screen, start the engine. Do you still get flicker? If you dont then its possibly from your signal cable, if you do then its power foltering.

You can buy a 12v switching psu for ICE and these will filter input noise which could be an option???

cheers matt....i'll have another look..........but,if i unplug the video cable h/unit output to monitor input connection the monitor goes off...........

[orionn2o]

ahh thats a pain !

[666damned]

pmsl......tell me about it......