Another fix to my '817. A while back I learned the hard way that shorting external 12v to the chassis can, and probably will, burn out a trace on the main circuit board. That's a fairly easy fix & it didn't take long to get the radio back on the air.

But there was another problem. The radio ran fine from external power, but not from the battery. Grrr I finally got a chunk of time to fix that.

If you look at the schematic, you'll see that the plus pins of the battery connector (JP1001, pins 3 & 4) go directly to two diodes, the cathode of D1083 and the anode of D1084. When I looked at the circuit board, there's an internal trace that makes that connection -- the two diodes are right next to each other on the circuit board, down by the ext. power connector, J1017. As it turned out, that internal trace was open. Whether it was the trace or the plated through holes I couldn't tell. One of the through connections is something called TP1083 (What's TP? Through Plate? Test Point? Terminal Point? whatever...). How I fixed the problem was to tack solder a wire from TP1083 to the cathode of D1083. Both of those are accessible from the top of the circuit board, so you don't need to take the board out or even remove the bottom cover. Just disconnect the battery when making the repair, if you ever need to.

It's an easy fix. I don't know if this happened when I fixed the other problem or it just happened to develop independantly -- or maybe the slight stresses on the board as I worked on it caused the open. In any event the fix is pretty easy. There's enough room around the solder points that super-human precision isn't required.

BTW -- if you DO take off both covers, don't forget to put the plastic piece that goes around the mic and sp/ph connectors and the sp/ph switch before you put the covers back on! I forgot to & well, had to take it all apart again. Yep, I'd put all the screws in before I noticed!

Lesson learned -- hook up the external power cable FIRST and then plug it in!