[TechAssist] Re: 60 Cylce Hum in Video in a new house
- From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 11 Jun 2003 12:03:38 -0400
My knowledge on this is somewhat limited,but usually if it clears with
the isolation transformer on the pffending set, there is a "ground loop"
leakage path somewhere.
Do I understand the offending PTV is ONLY fed with line out video from
the digital box's "video out RCA jacks and no RF? Can you hook up a test
set right at the PTV and move the cables over to the test set vid in,and
will it show hum?
Is the hum maybe being picked up by the video cables on their way to the
PTV?
Poorly shielded video cables? Too long a run?
I wonder if the hum is at the box where the video is connected.Need more
input.
Phil Bader
tvtech wrote:
>
> I am working a new house, which was wired by a surround sound contractor,
> the cable comes into the utility room, to a distrubibution amp, the cable
> is then routed to the "AV" closet, to the digital cable box, with only
> video routed across the room to the projection tv. Somewhere, between the
> dist. amp & thc AV closet, the system is picking up 60 cycle hum in the
> video. There are only 2 ways to get rid of the hum, remove the cable
> connection @ the AV closet, the hum is gone completely, if I reconnect at
> the AV closet, & disconnect the other end @ the distribution amp, the hum
> is minumized, but is still present. The other method I have found to
> remove the hum is to install a sencore PR57 insolation transformer on the tv
> ac input. The other sets in the house are not affected by the hum. I am
> interested in suggestions for some type of AC insolation device, other than
> my PR57. Thank you Allen Josephsen The TV Store tvstore@xxxxxxxxx
>
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--
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx
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