Re: Cossor 3339 Oscillograph(Scope).
The work continues... I have definitely taken on more than I realised! David warned me that the wafer switches and potentiometers may cause some problems - he was correct. Several of the pots had the same fault. The wiper consists of a piece of spring steel which has a right angle bend at the end which is pointed. This locates in a 3mm diameter disc of metal which forms the actual contact against the track. On several of these the disc had come away and the sharp point on the wiper had scored a deep groove in the track which was open circuit from the wiper. I tried making a slightly larger diameter brass disc on the lathe to bridge this but it did not work. I have managed to find enough spares although some are quite worn.
On the wafer switch front you will notice that on the left hand chassis the swiching shaft for the 4 section wafer switch had not been inserted. While doing this one of the rotating wafers got caught and broke - it could have been cracked already. I had a replacement switch but of a different pattern so all 4 wafers had to be replaced - all situated below the now laced wiring. It took several hours of work to do this! The undersides are now complete and work is ongoing on the upper surface wiring.
Mark
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