notes@ucf-cs.UUCP (12/07/85)
Subject: Kenwood TR-2400 Blown UP! When I got my TR-2400 (used) I received a few "Weak Modulation" signal reports and so I proceded to turn up the mike gain pot that was clearly marked on the schematic and was easily found on the circuit board. I figured that such a slight change could not possibly get me in to trouble. I was wrong. Upon putting the radio back together I asked for a signal report to see if my modulation was up. It was. I thought I had it licked until a few days later I tried to access the local autopatch. It completely ignored me. Hmmm, I thought, let me turn this little pot over here that increases the voltage from the touch-tone chip. That didn't work. I had better look at this on the scope, I thought. I probed around with the comparatively large scope probe and blew out a coil. The coil is made of a fine wire wound on a resistor. Its purpose is to act like a fuse. The only problem is that the resistor still conducts. Not aware of this at this time, I pluged it in to a 10 amp 12vdc supply. The radio worked. Unplugged it, and it didn't. Figured the battery was shot. I tested the battery and found that it was good and figured that there may be something wrong with something between it and the circuit. So as an experiment I wired the battery in through the external voltage connector to see if it would work. It didn't, it blew up instead. I had connected it backwards. Several of the transistors literally exploded, and some didn't. I still haven't figured out where all the non-exploded bad transistors are. Has anybody faced such a problem with this rig, or is it just me. If anyone has any contructive comments I would appreciate them. Dennis Hawkins / N4MWD