Vidor “Lady Margaret”: Short H.T. battery life
We had been rather concerned by the fact that H.T. batteries had been failing prematurely in one of these receivers. The lid switch was suspected, of course, but it appeared to be in order. However upon insulating the contacts with sleeving, a leakage which had been registered on an insulation tester disappeared. Next we disconnected two of the switch contacts, leaving the common tag connected, but on closing the lid the leakage was still present.
It was found that the H.T. negative lead had been connected to the common switch contact (not as shown in Trader sheet 1153), which was short-circuiting to chassis via the lid stay, fixing screw and metal panel when the lid was closed. We reconnected the leads so that the common tag went to chassis.