UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Ed_Dinning · 14th Jun 2006, 9:45 pm

Hi Andi, this is where running an AC/DC tele through an isolating transformer becomes useful as there is no "common mode" voltage on the chassis that can zap the test equipment when it's ground is commoned to the test equipment ground.
There are "dirty" techniques you can use but not worth trying if you are unsure of what you are doing.

The signal lead is not so much of a problem. A suitable value capacitor for the frequency of the signal being applied, and of a suitable working voltage will block the DC and get some sort of signal through. Getting the levels right and a good picture is a different matter!

HTH Ed

14th Jun 2006, 9:45 pm	#70
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: TV22 Restoration Hi Andi, this is where running an AC/DC tele through an isolating transformer becomes useful as there is no "common mode" voltage on the chassis that can zap the test equipment when it's ground is commoned to the test equipment ground. There are "dirty" techniques you can use but not worth trying if you are unsure of what you are doing. The signal lead is not so much of a problem. A suitable value capacitor for the frequency of the signal being applied, and of a suitable working voltage will block the DC and get some sort of signal through. Getting the levels right and a good picture is a different matter! HTH Ed