An article by Stuart Mason. 8BS will not accept responsibility for any damage that you may do to yourself or your equipment whilst attempting to carry out the following modifications to monitor cables. If you are not completely sure that you understand theinstructions, don't do it! How to construct a cable to drive a CGA/SGA/SVGA monitor from a BBC micro. 1. BNC connectors to BBC RGB 6 pin Din.Using an old BNC video cable. Viewed looking into the Din plug towards the micro Link pins 2 and 4 with insulated wire. 3 2 4 Sync A 1 5 Ground
BNC Din Plug
BNC 3 Screen Wires
Tools Required: 1. Soldering Iron. 2. Solder. 3. Wire Cutters. 4. Insulating Sleeve. 5. Insulating Tape. BNC to 6 pin Din notes. With this type of cable there are 3 BNCplugs which drive the video screen represented by "RGB" on the back of themonitor. Take the old cable and cut it so that you have the three BNC connectors and at least three feet of cable. Carefullyremove 2.5 inches of the outer sleevingfrom the cut end the cable. Join the three outer earth screen cables by twisting the wire together, solder to secure. Then solder a short piece of insulated wire to the end of this wire. Join the two pins 2 and 4 as shown witha piece of insulated link wire. Now fitinsulation sleeving over the three coloured wires and solder to the Din plug as follows: Red feed to pin 1. Green feed to pin 2. Blue feed to pin 3. Pin 5 is the ground (earth). Solder theinsulated wire from the three joined screen wires to this pin. It is VERY important that none of the wires short with any of the other wires. Check that all bare wire is insulated by plasic sleeving placed over the wire before soldering or insulation tape. Because there are so many variations ofscreens, you may have to try different combinations of switch settings on the monitor to get the picture right. I've tried this cable and the more popular 9 pin sinch connector cable with various monitor screens such as IBM XT and AT, NEC, Hitachi, Microvitecand Panasonic. I have not tried it withthe Amstrad, so I am not sure how theirscreens are driven. These cables could be of use to someonewho has a large screen IBM/PC clone monitor which can then be used with a BBC micro. Because the PC monitors are designed for higher graphics standards,they do improve the quality of the BBC display with respect to colour, sharpness and better colour definition.2. 9 Pin sinch connector to BBC RGB 6 Pin Din. Some IBM PS monitors have a 9 pin socket on the back. Labelled "TTL". Usually these monitors are of the CGA and EGA type. Construct the BBC end of the cable as follows using ordinary wire which seemsto work fine: 3 2 4 Sync A 1 5 Ground
Ensure that the wire is no longer than one meter. This is the same as method one (BNC to 6 pin Din), but without linking pins 2 and 4. Then solder the wires to the 9 pin sinch plug as follows: Male Sinch Plug 5 4 3 2 1 9 8 7 6 Viewed looking into the plug going intothe monitor socket. Pin connections are as follows: Male Sinch plug Din plug 1 ]]]]]]]]ground]]]]] 5 join ] 2 ]]]]]]]]Red]]]]]]]] 1 together] 3 4 ]]]]]]]]Green]]]]]] 2 5 ]]]]]]]]Blue]]]]]]] 3 8 ]]]]]]]]Sync]]]]]]] 4 Join pins 2 and 3 with insulated wire.