Modifications for the ICOM - RogerK

Also probably would apply to IC 735 and IC 745 as well.The symptoms were distortion on transmit, a very unstable display, often tuning dial would not move frequency, display wouldgive all kinds of random numbers, sometimes no numbers at all on sections of display readout. This appeared to be a mechanicalproblem, as a sharp "rap" on the case would change things, sometimes curing it temporarily. We pulled off the covers of the set,and gently tapped each board. The PLL board appeared to be the culprit. This is the small covered board to the rear left on theunderside of the 740.We popped off the little cover over the board, loosened the 4 mounting screws and took out the board. Everything looked good,but the points on the board that contacted the metal standoffs were corroded and dirty. We flowed fresh solder around the screwholes on the board (underside), cleaned the standoffs and cleaned the chassis where they connected to it. This cured theproblem. Interestingly enough, we did the same fix to an Icom 22S 2 mtr rig several years ago that would keep going out of"lock". It cured that problem as well. The bottom line is, make sure all your board to ground/chassis connections are real clean.Just a thin film of crud can cause all kinds of problems on a unit that uses the mounting screws as the ground return. Sometimes(but not always!) just loosening and retightening the mounting screws will help the problem.This modification is read 503 times.top of page19-07-1998(IC-745) IC-745 - PROBLEM: Tuning counts slowly downI have a problem with my 745. When I rang Bellevue, WA, they said: Never heard of it. My friend in LA who has the samepronlem got the same anser.The problem is as follows:The tuning counts slowly DOWN whether it's memory or VFO. I temporarily used the set by turning the dial in the UP directionfaster than the countdown and then used the lock button when the set arrived on the desired frequency. The XIT?RIT can beused for small corrections.My friend who has a complete professional lab at his disposal found a temporary fix. He grounded pin 40 of the I/O IC whichsteers the CPU. Everything workds fine except that you miss the slowest tuning speed and that the UP/DOWN button on the micdoes not work. I did the same and my set work the same. The tuning is a little bit coarse now but usable except you have to becareful especially with RTTY or AMTOR.The local ICOM repair shop is too busy at the moment with their normal work, and I don't like to be without this set for too ong atime.I can't use the 730 to drive my linear at least not without a lot of trouble. I suspect thqt one of the two transisstors has gone butwhich? I just wonder if any of your readers has had the same problem and fixed it. (ED Note: Anyone have the solution?)(Thanks, Bob Bartelings, VE6CBN, 170 Haysboro Crescent, Calgary, Alberta Canada T2V 3G3)This modification is read 866 times.top of page19-07-1998(IC-745) ICOM IC-745 UnlockedLocate the RF board on the side of the radio and cut the light brown wire at jack 7., which is going to pin 1. Your transmitter isnow unlocked.This modification is read 1021 times.top of page30-03-2001(IC-745) RAM Card Backup Battery Replacement Instructions