EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

I've had my AW15 in the Lido cabinet for over 30 years. Recently, it quit playing. This is significant because it was still sealed with rivets. To repair it, I was going to open a time capsule. I was also interested to see what the wiring looked like - we have many schematics for the AW15 - what would this chassis look like?

The serial number is A-263. I don't have any confirmed dates in prefix A, but 263 is early, since all the AW15 sets begin at 250 in each prefix. The set has a 55 detector, so I started with the Rider's diagram marked "Early". This matched the set exactly in the front end, including the two sets of resistors on the sensitivity switch. The two diodes in the 55 are tied, as in the Early diagram. 

As I got to the audio stages, things didn't match up at all. I pulled the Rider's "Late" diagram, and mostly got back on track. From the plate of the 55 on back - this set matched the Late diagram except for the coupling cap between the 55 plate and the volume control - it was still a .1 mfd cap, not the value shown in Late. I've rather crudely cut and pasted the two diagrams together to create an accurate schematic for this set. 

Here are differences noted between the diagrams:

1. IF/RF AVC control (cathode/grid circuit of IF/RF tubes)

2. Sensitivity control. (2-pole vs/ 1-pole)

3. Audio stages (use of transformer for plate B+ or feed through resistor)

4. Bias on detector (see #2)

5. Full wave or half wave 2nd detector connections

There are probably more. What we can say is this - AW15 sets really seem to have been in continuous evolution through the entire production. Look at all the available schematics and overlay the areas that match your set. I was fortunate to be able to examine an unmodified set in this way. BTW - it is playing well. The sensitivity control isn't what I'd like, At least sensitive position, it only allows very strong locals, the IFs are almost cut off. Works well on the first two settings. 

Kent

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