Modifying the CC90-232 interfaceCC90 is a 38400 baud serial transfer program (about 4ko per second) between today computers and the Thomson. To make it work right, you need some material :
The little electronic modification won't alter your interface faculties.
EquipmentThe CC90-232 interface, as such, can not work properly in serial mode on rare Thomson what have -5 volts supply, in addition to 12 volts. The designers of the CC90-232 interface used simple components to convert 12 volts into -12 volts. The voltage of -5 volts is used to prevent the power loss due to dissipation. Nowadays, some components are able to convert a positive voltage into a negative voltage without loss. The deal is to create the -12 volts from the 12 volts supplied by Thomson ... without passing through the -5 volts. What is necessary:
Scraping off the stripboardYou must first scrape off four strips in the middle of the stripboard. Use, for example, a retractable blade knife to cut the strips either side of the zone and then scratch the copper with it. ![]() ![]() Soldering the componentsA pretty simple wiring. To further facilitate the work, start with straps that you will make with the pin connectors of the two capacitors. Solder then the IC and finally the capacitors. Finally, solder the three wires (here white, green and black, but colours don't matter). Interface side, the white wire is connected to the 12 volts, the black one to the ground and the green one to the well expected -12 volts. ![]() ![]() ![]() ![]() ![]() Be sure to solder the IC straddling the scraped part in the indicated direction. Testing the circuitUse an electric battery which not exceeds 12 volts. Connect the white wire to the +, the black wire to the - and check with a multimeter that there is an inverted voltage between the green wire and the - of the battery. Desoldering the useless componentsThis operation will allow you to put the voltage converter into the space created once everything is finished. The identification is all the easier given that the name of each component is printed on the circuit board. ![]() ![]() ![]() Just remove:
Connecting the interfaceConnect the green wire to the + of D3, the black wire to the - of D3, and the white wire to 12 volts (thicker circuit on the left), after reducing the wire to a minimum length. Also check the inclination of the solder so that the wires go in the opposite direction of the ribbon cable. ![]() ![]() Now wrap your wiring in a thin cardboard to avoid short circuits. ![]() Integrating the voltage converterPlace all at the location of the desoldered components and close the interface. Don't forget to replace the insulating sheet between the two parts of printed circuit boards. Your interface is ready for use. |