Issue 2 Net Mods
****************

Picture set showing the modifications required to issue 2 and 3
BBC Motherboard when fitting the Econet interface.

These pictures follow the instructions given in the Fitting
Instructions for the Econet Service Centres which differ somewhat
from the details given in the Service Manual.

1.  	Establishing shot of Issue 2 solder side, with location of 5
	ICs shown in red.  From left to right: IC 97, IC 26, IC 96, IC 95, IC 89.

2.	Solder side IC 89, with location of track to be cut shown circled in red.
	Direction from Service Centre instructions reads:
	"Cut the track adjacent to IC89 pins 27 and 28"
	N.B. This modification does not appear to have been done on this board.

3.	Solder side IC 95, with location of IC 95 shown with broken red line.
   	Track to be cut in two places circled in red.
	Direction from Service Centre instructions reads:
	"Cut the trace adjacent to IC95 in two places"
	N.B. the top cut appears to have been done but not the bottom cut.

	Location of points to link with wire circled in blue.
	Direction from Service Centre instructions reads:
	"Relink the two ends of the cut track adjacent to IC95, but keep the link
	 away from IC95 (to avoid crosstalk)"

4.	Solder side IC 91, showing a cut track highlighted in red.  Possible
	alternative to cutting the track between pins 27 and 28 of IC 89?
	This track leads from IC 89 but appears to terminate at the point where
	the cut is made on this board.

5.	Solder side IC 26, showing pins 8 and 9 highlighted in red.
	Pin 9 has two wires soldered to it, which connect to ICs 96 and 97.
	Directions from Service Centre instructions read:
	"Link IC26 pin 9 to IC96 pin 19"
	"Link IC26 pin 9 to IC97 pin 4"
	Pins 8 and 9 have a 100pF capacitor soldered between them.
	Direction from Service Centre instructions reads:
	"The 100pF capacitor should be soldered between pins 8 and 9 of IC26".
	N.B. the directions specify that this modification should be done to the
	component side of the board, but it has been done to the solder side of
	this board.
	Track adjacent to pin 16 highlighted in blue, appears to have been cut.

6.	Solder side IC 97, showing pin 4 highlighted in red.  Pin 4 has a wire
	soldered to it, which connects to IC 26.
	Direction from Service Centre instructions reads:
	"Link IC26 pin 9 to IC97 pin 4"

7.	Solder side IC 96, showing pin 19 highlighted in red.  Pin 19 has a wire
	soldered to it, which connects to IC 26.
	Direction from Service Centre instructions reads:
	"Link IC26 pin 9 to IC96 pin 19"

8.	Component side showing C17.
	Direction from Service Centre instructions reads:
	"C17 (2n2) is a replacement for fitted C17"
	N.B. this board does not appear to have a replacement C17.

9.	Component side showing IC 7 with track between pins 19 and 20 highlighted
	in red.
	Direction from Service Centre instructions reads:
	"Cut the track that emerges eastwards from between pins 19 and 20 of IC7,
	between the IC and the through-hole"


ISW 7/i/2013