WARNING: Make sure your antenna connector isn't hot!

[radiotvnut]

Was playing around with the '98 Zenith that I did the tube swap on with it connected to the Channel Master converter box without problems. For some reason, I decided to connect a DirecTV box to the set just to see if it would power up and display anything. I connected the coax cable from the box to the set and as soon as I plugged in the AC cord to the box, I heard a loud hum, detected a burning smell, and the lights dimmed in the shop. Unplugged everything and tried the box again and no problem this time. I then suspected a problem with the TV; so, I checked between the outside conductor of the coax connector on the TV and earth ground and got the full 120 VAC! I reversed the AC plug and got zero volts. The TV plug is polarized; but, I can plug it in both ways in the cheap outlet strip I was using.

Had I sold this set to someone, one of three things would have happened:
A. They would have blown the house fuse and maybe damaged the TV.
B. They would have got a good jolt.
C. They would have ended up in a pine box.

In the past, I have taken for granted that the antenna connector is always cold. Probably because I've never really had a problem with a hot antenna connector. I've only heard about hot antenna connectors a few times from other repairmen. You can bet that from now on, I will check every antenna connector on all sets I fix to make sure they are safe. The last thing I'd want to happen is for someone to get killed over a set that I worked on.

This Zenith TV uses a switching power supply with the "hot" ground being on the primary side and the "cold" ground being on the secondary side. Obviously, something is shorting the grounds together.

I just thought I'd pass this along in case anyone else has made the same mistake I did by assuming the antenna connector is safe. Check those antenna connectors!