[Mark James]

The second 339 was more of a task. I had expected some issues as I had sprayed the chassis and therefore had to provide separate earth wires in many places - in fact this did not cause any problems! I transferred the good tube and valves from the first 339, did all the basic checks and then powered it up as before. Rapidly turned it all off when there was sparking from the back of the underside of the mains transformer. Very dissapointing as I had checked the integretity of all the windings and done insulation tests between all of them. Further inspection revealed one of the connections between windings had come adrift where it dived into the windings. My first thought was to replace it with the transformer from the WWII 'scope but on removing and testing this several of the windings were O/C. The only option appeared to be a repair which I did in situ by lifting the transformer an inch, using a scalpel to shave a hole in the paxolin board around the broken wire. (The paxolin board covered the end of the transformer.) The small protruding piece of wire was then soldered to a piece of tinned copper wire which was then soldered to the loose end of wire and encased in white heat shrink tubing. The attached pictures show the procedure. (Continued in next post.)