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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
A problem with A/C hum



New User

Oct 17, 2020, 6:10 PM

Post #1 of 2 (444 views)
A problem with A/C hum Can't Post

I have a setup to beable to record to a blank DVD from Spectrum DVR box. When I am setup to record to a blank DVD there is a small amount of A/C hum on the recorded DVD. If I play a DVD movie that I got from the store or the DVD was recorded on a different DVD recoreder, there is no A/C hum on my HD flat screen tv. Also if I watch tv via the HDMI cable directly connected to the DVR/cable box there is no A/C hum. See the dropbox link of the drawing that I made.

I have swapped out the cables between the DVR and the DVD recorder and from the DVD recorder to the tv and I can't get ride of the A/C hum. I think I have a ground loop but I don't have the test gear to hunt for it and to get on my hands and knees to get under the desk or behind the tv stand to get at the power strip is darn near imposable for me. I can get down, it is the getting up that I have a problem with. Also my electronics knowledge is ancient.

I started working on 2 way radios, radios and tv's while they still had vacuum tubes in them and self service tube checkers in the grocery store. I still have an SCR-284, SCR-300 and a SCR-536 that I fixed up in my ham shack, and they still work. I had to retire 1n 1995 do to micro tremors in my hands. I couldn't hold the soldering iron still anymore.

Steve KC7BYP

New User

Dec 28, 2020, 6:36 PM

Post #2 of 2 (239 views)
Re: [reble] A problem with A/C hum [In reply to] Can't Post

you might check if all are plugged into the same outlet. if so then try separating them. Do you have an Isobar or an isolation transformer? Or you could try to bond the devices together with some wire. Lastly you can try to use a torrid or iron ring like used on power A/C cords. wrap the in/out cable around one of those. It might help filtering out the 60HZ hum.

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