A dual-45-output (first version) Model 90 chassis was once on my bench which, upon initial power-up after a complete recap, had no reception.

The coils were checked and double-checked; they all had good continuity. (You may recall that older Philco sets are prone to having bad coil windings.)

Thus I began a general check. The set would pass an IF signal by feeding IF to the grid cap of the IF amplifier tube, and then in turn, the first detector tube. It would even pass IF through the RF amplifier tube.

OK, it sounds like oscillator trouble. The coil (44) is good; what about the trimmer condensers?

A dead short was discovered across trimmer (42). There is a resistor and a mica capacitor connected in parallel with this trimmer.

In order to find which of the three components was shorted, one leg of resistor (43) and one terminal of mica condenser (41) had to be removed from one side of trimmer condenser (42).

Neither the trimmer (42) nor the mica condenser (42) showed any signs of a short. However, resistor (43), which is normally 50,000 ohms, was reading a dead short.

Resistor (43) was then replaced with a new 51K resistor. However, that was not the end of the trouble; the set still refused to play.

Mica trimmer (42) was then replaced with Philco part 04000-A, a trimmer salvaged from a slightly newer Philco chassis.

Mica capacitor (41) was also replaced with a new 680 pF unit for good measure.

After replacement of these parts, the set finally came to life. Following a complete alignment, the Model 90 was ready to go.