TRV900 problem?

Jackie_Chan_Fan wrote on 5/30/2004, 6:49 PM
I have a sony TRV900 and i love the thing. Though recently i've noticed that when i plug in the firewire to it, and have it hookd up via svideo to a television... I notice two slightly noticeable horizontal lines that crawl up the picture.

This doesnt happen when i have svideo by itself hooked up to a tv, but only when i have firewire and svideo hooked up at the same time.

Deos anyone know what this interference is? It doesnt capture video with these lines, nore does it record with these lines. I clean the camera and take amazing care of it.

I'm curious if this is normal and perhaps i havent noticed it in the 2 years that i've owned it.

It doesnt seem to be a problem and i can work around it.. but it is a anoying. The lines are just two slightly visible horizontal lines that are like %1 percent brighter than the pixels that its rolling over. (the lines roll upward)


Opampman wrote on 5/30/2004, 7:26 PM
JCF - These are hum bars, probably. Usually caused by a broken shield (ground) or from having two pieces of equipment plugged into outlet with different grounds or neutrals on the power.
johnmeyer wrote on 5/30/2004, 7:33 PM
Opampman is absolutely correct. The solution is to plug the camera power supply, the computer power supply, and everything else, all into the same plug in the wall (using a power strip, of course, to get enough plugs).

If you cannot do this, then you must use either an isolation transformer beween the "mains" (as the English call the power coming from the wall plug), or you need to use a device called a "humbucker" between the video source and your camera (i.e., you plug your composite or S-video cable into this thing). If you type "humbucker video ground loop" into Google, you'll get lots of information on this:

Humbucker Ground Loops
Jackie_Chan_Fan wrote on 5/31/2004, 6:49 PM
Thank you very much Opampman and Johnmeyer. I would have never figured that out. Very interesting.

Will these hum bars do any harm to the camera if i continue to work like this?

FuTz wrote on 5/31/2004, 7:47 PM
Maybe, just to be sure, check it out with a battery on the cam instead of power supply?

For my part, I got a PD100 (pretty much the same as your TRV900) and I always use a battery since these power supply connectors on the cam are fragile and tend to get some "loose". Big battery; got juice for around 8 hours. enough time every time in my case..
And I charge these batteries on a Wal-Mart universal charger that will also take my Canon G2 stills cam battery...

I don't use my cam for external preview though, since it always sucked on my comp'.
John_Cline wrote on 5/31/2004, 9:14 PM
The ground loop can also be caused by the ground of the cable TV coax being at a different ground potential than the household AC wiring. If you have cable TV hooked up to your TV, try disconnecting it and see if the hum bars go away.