In the last post I discussed the little monster on the right. This is a variable resister, or so the service manual says, that controls the tape tension of a TEAC A-4010S reel-to-reel tape machine. Tape tension can go out of spec and this is one of three resisters that are used to control that tension.
Sharp eyes will note what I mentioned last time, this variable resister is, in fact, a potentiometer. It is not what anybody would call “high tech”, but it gets the job done.
Unfortunately, one of these resisters had a broken band and a particularly crucial adjustment could not be made. I had to dig up a replacement band.
I found a few options online, but settled on this set of resisters that included the side frames, bands, and appropriate screws. You will note that I have already removed one of the bands from the center resister.
I did not want to replace the entire set of resisters because I was not sure if these were any better than what was in the machine at that time. You can see that these were pretty grungy, although they were supposed to be totally functional.
Better safe than sorry, so I took one of the bands and put the rest of the parts in storage in case I need them later.
The image on the right shows the broken resister band that I had to replace. You can see some wires soldered to a terminal. The break is near that solder joint. This was a little tricky to work on because I had to de-solder the wires in a confined space.
In this photo we see the “new” resister band. It is about 50 years old so the term “new” is more of a concept than a fact. Still, once that little stub of a wire was de-soldered and removed it worked perfectly well.
Once the soldering to attach the new wires was done, I was able to make the final tension adjustments. After a few minutes of fiddling I had those adjustments nailed down, and the A-4010S was ready of the big test.
Check out the video on the right and you will able to see and hear the machine playing a tape perfectly.