Service manual

Sockets
Skt
Fitted
Function/Specification
SK1
Yes
RGB video socket.
This is a 15-way mini D-type socket providing
an interface to RGB monitors and Scan TVs.
RGB video levels are 0.7V Pk-Pk into 75 Ohm.
Sync voltage levels are >= 2.0V (TTL).
Pin Signal
1 RED
2 GREEN
3 BLUE
4 ID[2]
5
6,7,8 OV
9 +5V (750mA fuse)
10 OV
11
IT)
12 ID 1 /SCARY func. switching
13 H NC
1
14 VSYNC/CSYNC
15 ID[3]
SK2
Yes
Stereo headphone output.
This is a 3-way 3.5mm stereo jack socket
providing output to "Walkman-type" 32 ohm
stereo headphones.
SK3
No
9-way mini-DIN providing connection for
quadrature mouse. Reserved for future use.
SK4
Yes
6-way mini-DIN socket providing the
connection point for the keyboard.
SK5
Yes
Parallel printer port.
25-way. D-type socket providing a parallel
printer interface.
Pin Signal Pin Signal Pin Signal
15 ERROR*
2 PD
1 STB* 8
PD[6]
0" 9 PD
7 16 INIT*
3 PD
1 10 AC
17 SLCTIN*
4 PD
2 11 BSY 18-25 OV
5 PD
3 12 PE
6 PD
4 13 SLCT
7 PD
5 14 AUTOFD*
SK6
Yes
Econet socket.
5-way DIN socket for connection to Econet
LAN. Note, this is an upgrade.
Pin Signal
1 DATA
2 OV
3 CLOCK*
4 DATA*
5 CLOCK
SK7
Yes
Econet upgrade module socket.
17-way header used in conjunction with SK8
to provide the electrical connection point for
the internal Econet upgrade module. This
module is identical to that used on Acorn
Master series and Archimedes computers.
SK8
Yes
Econet upgrade module socket.
5-way header used in conjunction with SK7.
SK9
Yes
Backplane socket.
Systems are normally supplied with a 4-way
backplane already installed.
SK10
Yes
Mem expansion socket (1, 2 or 3MB upgrade)
Appendix F - Main PCB links, plugs & sockets Issue 1, November 1991 F-3