Loud Hum problem

[kevs]

I was playing a DVD and was getting a real loud hum. the DVD player has to pass through a DVD recorder that sits right on top of it. The hum went away when I unplugged the orange video cord between the two machines, but I could not figure this problem out. Then the problem went away a few days later. Any clues to what that was? thanks!

[CrayonEater]

If it's not simply that your audio cable was loose, it could be a bad ground in either device (or your stereo/amp if you have one) or inductive interference from the 120 VAC power going into one of your devices. That you removed the cable does not necessrily mean it was the DVD recorder; you just may have shaken it or something else enough to temporarily reconnect the ground or move an exposed power lead farther from the audio jack on one of your devices. Because this is a potential safety issue, I'd get these devices serviced. At a minimum, keep the devices unpowered unless you are using them until you can isolate the device that appears to be causing the problem, and bring that device in for service.

[kevs]

Crayon: thanks , maybe it's the grounding thing, could be hard to isolate. the player has been working fine. my finger was pointing at the recorder as it just came out of the box new. Today, seems to be ok, even with both in conjunction.

I guess if if problem returns, I should try to isolate problem, but problem was happening only when the new recorder was in the mix. I was able to use player alone fine. In fact, I think both of them were ok alone. Only when had cables going from one to the other did the hum come.

Would not that be odd, a brand new recorder has some grounding problem? or maybe it's something else. hopefully a one time event?

[CrayonEater]

Actually it's not that strange. A wire or an internal assembly may easily have been knocked loose during shipping and handling. Ground problems also usually occur either in very damp/humid environments, causing corrosion and separation, or after years of a device or wiring being subjected to heating and then cooling and then more heating and then more cooling. Wires and current-carrying parts work themselves apart.

Unless you're sure it was the fault of a loose or bad audio cable, or maybe something else touching the metal of cable connectors, I'd take the recorder back. Again, if this is a ground problem, it has become a safety issue, not merely an inconvenience.

[kevs]

thanks Crayon: well, if seem to have gone away, what definitive tests can I do before shipping things back.

[CrayonEater]

Lightly bump and shake your devices around a few times and see if the problem reoccurs, maybe repositioning them slightly at odd angles. You could try keeping the audio cable partly out of the jack as if it were improperly inserted. Or, if you remember if any other wires were nearby or touching the audio cable or DVD recorder case, especially if exposed, try touching them against the outer metal of the audio cable or DVD recorder case and see if the hum reoccurs.

[kevs]

Crayon: it was definitly the yellow video cable that when I unplugged it noise went away.