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From: gv@hou2e.UUCP (A.VANNUCCI)
Newsgroups: net.video,net.analog
Subject: Re: Adding Video Input to a TV Receiver
Message-ID: <743@hou2e.UUCP>
Date: Tue, 19-Nov-85 13:22:49 EST
Article-I.D.: hou2e.743
Posted: Tue Nov 19 13:22:49 1985
Date-Received: Wed, 20-Nov-85 20:24:06 EST
References: <6263@amdcad.UUCP>
Organization: AT&T Bell Labs, Holmdel NJ
Lines: 28
Keywords: TV VCR
Xref: watmath net.video:1674 net.analog:527

> I would like to add a Video input to my Sears 19 inch TV receiver, 
> to obtain better pictures from my VCR.  Is there anyone out there 
> who knows if this is possible, and if so how difficult is it? Is 
> it worth the trouble in terms of picture quality ?
> Thanking you in advance for your suggestions
> 
> ----Ramesh

   The main reason why TV sets don't have a video input is that they
don't have an AC transformer in the power supply.  In order to save 
money, weight, etc. TV sets rectify the AC from the outlet directly
and, therefore, have a hot chassis.  If you connect a coax cable to
the video circuit input the shield of the cable must go to the chassis;
however, the chassis may be connected to the 117 V live wire, so that
you will get an electric shock when you touch it, you will blow fuses,
damage other equipment, etc. etc.

   From what I understand, you just need an isolation transformer to
power the TV set and then you can add a video input with no problems.

   An isolation transformer is just a normal transformer with a 117 V
primary and a 117 V secondary, so that the load is not directly
connected to the power grid.

		Giovanni Vannucci
		AT&T Bell Laboratories      HOH R-207
		Holmdel, NJ 07733
		hou2e!gv