Greetings: I still haven't fixed my R-7 yet but I'm making progress. I bought a digital control board from a TR-7 & tried it & found that all but the lowest 3 bands worked; the board outputs for the 3 bands that didn't work were all continually low, incidentally, while the outputs from the PROM that fried were all floating. Next I connected 8 SPDT toggle switches so that each would select either ground or +5V & connected them to the DR-7 board in place of the digital control board & used them to make a truth table documenting the successful patterns for each band. Not surprisingly, the patterns from the control board match those of the DR-7 output lines to the translator board. If anyone would like a copy of this truth table send me an e-mail off list.
My next step is to build something that'll respond to the band switch inputs with the required outputs, now that I know what they need to be. I've designed a circuit that'll do this using a 4-input AND gate for each band [11 in total; actually 6-4082s] plus inverters & [Schottky] steering diodes although possibly there are simpler ways to do this. I'll make a schematic for this circuit available once it's done & working properly in case there's any interest. 73s. Dave _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
