1950 Zenith Porthole Tuner Mistake

[VA561]

My Zenith porthole set was playing great every time I turned it on. The other day I turned it on and there was nothing but raster, no picture from my dvd player. I checked all of the connections and everything seemed fine. I took the cover off of the tuner and very gently rubbed the tabs on the channel 3 and 4 strips with a very fine emory cloth to remove any light corrosion. The picture returned but now I’m getting interference on both channels. Is there anything that can be done to bring back a clear picture again? Any help is greatly appreciated.

[Tom9589]

Get some tuner cleaner/lubricant. You probably only cleaned the contacts on the individual channel strips. The mating contacts may also be corroded. Just spray both the channel strips and the stationary contacts and cycle the tuner back and forth.

Good luck.

[kvflyer]

I might recommend not using any kind of sandpaper. Rather contact cleaner with a stiff rag or cotton swabs. If the contacts are silver plated, any abrasive will remove it.

[Electronic M]

Abrasive cleaning is a bad idea. Tuner cleaner and or a rubber pencil eraser are the 2 best things to clean tuner contacts with... If you don't have tuner Cleaner sometimes the eraser alone is enough.

You may have to readjust fine tuning after cleaning contacts... Some portholes make it easy, others have this goofy spring loaded shaft that you have to push in each time a new channel is selected to to the fine tuning... Sometimes they put it where you're at risk of touching the metal cone CRT while adjusting it..

[Yamamaya42]

"Sometimes they put it where you're at risk of touching the metal cone CRT while adjusting it.."

Being zapped by the anode HV let's you know that you are alive!

[Chris K]

I have the remnants of one on the back of my right forearm from 5 years ago that still hurts if I bump it accidentally. What was the thinking behind that design other than keeping amateur tinkerers from ever fooling around in the chassis?