Issue with GE "Portacolor III"

[kf4rca]

I think that set has a bridge rectifier power supply. So its ground is ground to that set only.
Those sets cannot have an external video input for that reason. Modern sets have a switching supply and the transformer in it provides the isolation for external grounded video inputs.
There are video transformers out there but they are kind of pricey ($22).
Those ground loop hum eliminators that are sometimes used by security camera installers do NOT provide ground isolation.
You can verify that with an ohmmeter.
Again congratulations!

[old_coot88]

Wao. Great sleuthing job! ...Mr. Dragonslayer.

And to think how i used to cuss those with just the intermittent 'griplet' problems.

[dieseljeep]

Originally Posted by kf4rca

I think that set has a bridge rectifier power supply. So its ground is ground to that set only.
Those sets cannot have an external video input for that reason. Modern sets have a switching supply and the transformer in it provides the isolation for external grounded video inputs.
There are video transformers out there but they are kind of pricey ($22).
Those ground loop hum eliminators that are sometimes used by security camera installers do NOT provide ground isolation.
You can verify that with an ohmmeter.
Again congratulations!

I didn't know you were trying to use an external video source with this chassis. You should've used a modulator that converts a video source to VHF channel 3 or 4. They're all over the place for a buck or two.
BTW, I'm a firm believer in GFCI receptacles. It saved a lot of damage to hot chassis sets when contacting the chassis to ground.