Modifications for the ICOM - RogerK

This modification can also be found at ICOM's own homepage on the following URL: "RAM Card Backup Battery ReplacementInstructions"This modification is read 737 times.top of page18-11-2001(IC-R71) RAM board programming interface & R71A modificationeMail-1: Lorand@QwestInternet.neteMail-2: N2CBU@ARRL.NETA word of caution before you begin:11 December 1999 by Andrew Gerald, N2CBUIt's possible that due to a wiring error, parallel port error or software incompatibility you might erase the contents of your RAMmodule. If your RAM module is from an R71A you can restore its contents from the enclosed "ORIG-R71.BIN" file. I do not haveany other "recovery" files and until some become available I urge caution. Perhaps it would be wise to test your interface on aRAM module from a R71A first before reading RAM modules from other radios. I will add "recovery" files for the other radios tothis archive if they are sent to me.*** Note-1: If the "WP" Write-Protect pin (see J2 on the interface schematic) is tied to ground instead of to +5v the criticallower RAM locations in the module are write protected. A simple modification to the interface board would be to add a writeprotect switch.*** Note-2: If the "/WR" Write pin (see J2 on the interface schematic) is left unconnected when testing the interface then theentire RAM will be write protected. Thus you can test without much chance of erasing the contents of the RAM module.Icom RAM board programming interface & R71A modification notesYou will need a CD4040 IC, a 78L05 voltage regulator, an 8-pin strip of 1" tall 0.1" spaced header pins, a 12-pin strip of 1" tall0.1" spaced header pins, a DB25M, a length of ribbon or other type cable, and a piece of perf board. For the prototype I used aRadio Shack part number 276-149 prototyping board. It should be noted that my prototype does not have an on-board voltageregulator. I included the regulator on a subsequent board I built in 1991 which I gave away.All parts may be obtained from Digikey (www.digikey.com) and certainly from other sources. A suitable header pin strip isDigikey part number "S1081-36" but any similar header pin material will work.Circuit layout is simple, just take a look at the ram module in the R71 and imagine how the header material will have to bepositioned. What you want to do is make a "socket" on the programming adapter which looks just like the "socket" in the R71A.Build up the circuit on a small piece of perf board with the 4040 in the center. The long side of the header pins will have to bebent slightly outwards for the ram module to fit. The ribbon cable from the PC will attach near the smaller header strip.