{Collins} 75S-1: Who Let the Smoke Out?



Hello All,
I recently purchased a S-1 station. I've started refurbishing
the 75S-1. Upon further inspection, what I had thought was
a sloppy wiring job on the Waters Q-Multiplier was actually a partial
rewiring of the 6.3vac supply to the meter and dial lamps. A short at the
dial lamp had partially melted the supply wire. In following the wire under the
chassis, I discovered that the insulation had melted in several places.
In fact, the heat even melted the cord of the wire harness. Ugh. So I had
to cut the lacing and replace the entire wire, from the meter lamp to the
rear power connector. Fortunately, the remaining wires in the harness were
undamaged. What luck. It could have been worse.

What is amazing is that the receiver worked for the previous owner, who was
unaware that the owner before him had experienced the failure and had attempted
a repair, albeit crude and insufficient.

So, my question is... has this short ever happened to anyone else? And how could this
have happened in the first place? The shells of the lamp sockets are both
grounded.

My guess is that one of the shielded cables added for the Q-multiplier
modification had contacted the hot terminal of the dial lamp.

I'd like to understand what happened, so that it doesn't happen again.

Tnx, Dave - K3DX





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