[Gllug] ADSL on BT phone wires

[Chris Bell]

On Wed 09 Aug, t.clarke wrote:
> 
> The info I have is:
> 
> Pin      Function
> 
> 
> 2        'B'  =  -50V
> 
> 
> 3        bell    line from masyter to secondaries
> 
> 
> 5        'A'  =  0V
> 
> 
> 
> The A leg should be at earth potential.
> Presumably if you put a meter across pin 2 and earth you should get 50Volts
> and if you put a meter across pin 5 and earth you should get 0  !!
> 
> Presumably also if you stick a meter across 2 and 5  with the red probe on 5
> you should get a 50Vreading.  If the needle swings the wrong way then presumably
> the wires are connected wrongly !
> 
> 
> Tim

   Something like that is correct for the phone side, although the ringer
circuit is isolated by a capacitor so should show no DC voltage connection.
   ADSL hangs directly across the incoming pair of wires, but I would expect
similar DC isolation. That still does not confirm that reversing the
connections to the modem, (reversing the signal polarity) should/should_not
affect the ADSL connection.

-- 
Chris Bell

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