My FT-840 is not resisting
Yaesu FT-840
It might have something to do with the fact that my first rig many years ago was a Yaesu FT-707 with tuner and PSU and everything and it served me well for many years. That is a story for another day. But back to the present: When I pulled my trusty 707 from the mothballs a few weeks ago the caps were obviously dry and the VFO danced a merry dance on the display, and fixing it was not going to be a quick-fix. So when I found that Charles King ZR5CTM had a secondhand Yaesu FT-840 he wanted to sell, the negotiations with the minister of finance started. What? she said – you already have so many radios (pointing to a broken 707). To cut a very long discussion short, I ended up making Charles an offer which was accepted and the parcel was posted to me.
Disaster! The SA Post Office kept my precious parcel for 3 weeks, claiming there was a strike and that nobody was receiving any parcels. Yet on their track-and-trace, backed up by a phone call from the missorted post office branch, it clearly showed as having been sent to the wrong place twice. When I am calm again I will tell you that story of the strike that was not a strike.
But back to the main story. Upon receiving my cargo it was obvious that it had seen a few hard bashes along the way and there was something loose on the inside. It powered on but didn’t transmit and a few other strange behaviours. Googling it pointed to a very common problem: There is a resistor R2213 near a voltage regulator that runs very hot and sometimes burns out. Well, I know Dion at LA Radio who fixes radios so off to the workshop we go. It seems that the ceramic part of the resistor can get brittle and in this case broke from the shaking around. It was a simple fix to attach a 10 ohm 10 watt resistor to the back of the chassis with two connecting wires, and voila! tha radio works like new. We chose not to drill any holes in the chassis because we didn’t want microscopic metal shavings to settle inside the radio. Have a look at our mod:
R2213
The work we did is based on the article by John E DeBarr Jr aka November Alpha Eight Yankee [click here] but we had to use another component that is locally available. Instead of a 8.2 ohm or as some other websites say 9.1 ohm we only had a 10 ohm resistor available. It doesn’t seem to make any noticable difference. I took some pictures and can send you a PDF copy of my own work as we progressed but John’s article is quite clear with some very good instructions and pictures, for example this one shows the old resistor still in position (mine was broken):
R2213 inside
My 10 watt resistor hanging off the back of the radio gets very hot, so I can imagine what the original puny 3-watter must have felt like inside the radio. Definitely a recommended procedure to prevent further damage to the main PC Board.
