Subject:RELIABITITY MOD FOR TAPR-2's Thought we'd share a mod for the tapr-2's. (pk-80, mfj-1270, pac-com, etc.) We noted -5v problems, when using the 5 wire control mode of operation. (not noted when using x-modem programs) this mod not only improves the reliability of operation but also protects the I.C.'s using the -5 volts from being exposed to +5 volts do to a failure of the -5 volt regulator. The indication of failure is the dcd light flickers or stays on even when the radio is turned off. 1) Replace the 6.3 volt 1/4 watt zener whit a 6.3 volt 1 watt zener. (CR-6) 2) Install a 1N4001-1N4006 diode in paralell with C-10. (it may be installed on the bottom of the board the end of the diode without the bar is connected to the (-) side of the cap.) The modification seems to have worked very well on the 4 tnc's that we have installed it. It won't protect the tnc from all forms of damage but it should minimize problems in the -5 volt area. good luck. bob, nk8t (member, fara packet users group) ======= From:NK8T@NK8T Some MFJ-1270B TNC's may have the calibration and tx audio gain controls, (R-76 thru R-79) mounted incorrectly. As a result these P.C.B. mounted controls will have to be adjusted in reverse direction for proper operation. C.C.W. becomes C.W. and C.W. becomes C.C.W. The problem was first noted on unit S/N 01010124. The adjustment screws should be on the side of the control nearest the power off/on switch. If they aren't simply reverse the adjustment procedures with respect as to C.C.W. and C.W. BOB, NK8T =====  Amsterdam View Our Stats   CLICK FOR A FREE DOMAIN NAMES HTTP://WWW.YOURNAME.TK FOR YOUR OWN WEBSITE IF YOU CLICK HERE AND YOU CAN VOTE FOR OUR FREE WEBSITES IN THE TOP 100 LIST  WANT A TOP RANKING ? USE THE ULTIMATE SOFTWARE SUITE FOR WEB SITE PROMOTION  FreeWebSubmissions Submit Your Site To The Web's Top 50 Search Engines For Free THE ALEXA BANNER, THIS BANNER GIVES THE DALLY STATISTICS OF THIS FREE WEB SITE The World of Free Packet Radio Software Amsterdam The World Of Free Packet Radio Software Amsterdam The Netherlands |