Nokia D-Box/Pace Digibox PCB for Wideband LNB and Polarotor

"From: "Simon Millington" - view profile
Date: Sun, Jan 10 1999 12:00 am
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In article <369e2050.3128...*207.14.113.10>, Jomt...*the.beach (Jomtien)
wrote:

> This is the interesting (and vital) bit. Could you explain more what
> you mean by 'modified' as modifications usually kill the guarantee ?

I was not worried about the guarantee - in fact the lid was off the Pace
within 10 minutes of getting it home !

The mod does two things (all inside the box):

1. Detects the 22Khz band switching and sends 13 or 18 volts to the tuner
instead as appropriate.

2. Detects the Horz (18v)/Vert (13v) that used to be sent to the tuner and
produces a TTL 0/5 volt signal on a phono socket on the back panel. This
is used to switch an external pulse generator giving H/V output to drive a
polarotor. (My modified Nokia also has such an output and the standard 12V
switch is used to contest for polarotor and LNB control.)

The circuit required is relatively simple and fits into a match box sized
black box which sits on top of the UHF modulator in the Pace box. There
are five connections to make to the PCB and one to the new phono socket.

You need to make the following connections to the Pace PCB:

1. An earth 0v (Tuner case is good where it is mounted to the PCB.)
2. +5v supply
3. +21v that was used to feed the Pace's regulator supplying the LNB.
4. Connection to the tuner where the 13/18v supply / 22Khz was injected.
This is where I now inject my 13/18v for LNB band control.

(The track is cut at this point to block the Pace 13/18v and 22Khz.)

5.Connection to the point you have just isolated from the tuner injection
point. This is used to sense the original signals and generate my own.

The black box (had to be black :-) yes!) simply contains a voltage
regulator circuit controlled by a 22Khz tone detector circuit. I did not
even build the 22Khz detector - it came out of a standard Global A/B tone
switch.

The H/V output is generated by a voltage sensing circuit available for 98p
from Maplin Electronics.

My mod has been working for nearly 3 months now on the Pace box. The Nokia
for over a year. When I get some time I will get the circuit diagrams and
details of both receivers together with the pulse generator scanned and
put onto my home page. Got a scanner at work somewhere !

The Nokia mod details can be found on my web page:

http://www.cix.co.uk/~simonjm/