Re: Testing Isolation Transformer



Nomen Nescio wrote: 
On Fri, 29 Jul 2005 23:36:46 GMT, Ken Weitzel <kweitzel@xxxxxxx> wrote:


Anyway, can't help asking...  why the fireworks possibility?
All of those old sets had a power transformer connected
straight to the line (except power switch), and nothing
else connected to the line, so....



Truthfully, I don't quite understand why the need for an isolation
transformer.  But I've just read the need for such a thing often enough in
many places that I got one.  Sam Goldwasser mentions it in his FAQ and that
was good enough for me:

http://repairfaq.ece.drexel.edu/sam/tvfaq.htm#tvihw 

Hi Nomen...

Aha!  There what's happened... :)

First, I'm getting pretty old, (you knew that if I had worked
on those sets to pay for my education, right? :)  and am
easily confused and forgetful - if that's not enough, a stroke
victim too.

So, wait until someone else jumps in and corrects me or confirms
this, but meantime...

Virtually, if not all of todays sets, and for many years back,
are transformer-less.  The chassis is connected to one side of
the AC line.  Hence the need for polarized plugs (a bit of
safety while the set is in its case) and the desire for an
isolation transformer while its apart with the chassis exposed.

So if you work on something current, then either an isolation
transformer or great, great care is needed while you work on it.

But the set you're now involved with has a transformer in it,
so it's redundant to put a second (isolation) transformer in
series with it.  Can't hurt anything, but nor will it add
anything.

And just to be double-sure.  The transformer issue is only
*one* of the safety issues.  With it or without, the set will
still do you great harm if you aren't very careful.

Now wait for a second opinion 'fore you dig in :)

Take care.

Ken

.

Relevant Pages

  • Re: Isolation Transformer and DC corrosion
    ... but the correct method of connecting an isolation ... to have to install an isolation transformer in our dock box. ... therefore all the underwater metal parts of the boat, ... Once the AC power supply to the boat has no ground connection, ...
    (rec.boats.electronics)
  • Re: toroidial transformer winding question
    ... The plastic wrap insulation used on typical toroidal ... transformer is ever subjected to a serious overload - in some cases, ... A "safety isolation " transformer is one with a secondary voltage less than ...
    (sci.electronics.basics)
  • Re: whats everyone building these days?
    ... link obviously nicely wound his own ferrite core xformer; ... transporting the switching signal across the isolation barrier. ... I am gathering the parts necessary to build and test the transformer ... Inductor design and winding for beginners is a matter of much tedious ...
    (rec.audio.tubes)
  • Re: Isolation transformer
    ... electrically connected to the mains is a moot point. ... "In electronics testing, troubleshooting and servicing, an isolation ... transformer is a 1:1 power transformer which is used as a safety ... chassis of a TV, you will likely see sparks fly. ...
    (sci.electronics.basics)
  • Re: Isolation transformer
    ... "In electronics testing, troubleshooting and servicing, an isolation ... transformer is a 1:1 power transformer which is used as a safety ... expected "electrical connection to ground". ...
    (sci.electronics.basics)