Dismantling a Volume Expander

[Kent King]

Remove the top and tubes. Locate the two wires that come up from below through the grommets on the metal plate. Unsolder these wires, remove the screws holding the two terminal strips and remove the 8 screws holding the plate in place. 

Now remove the metal plate pulling it up and away from the end where the two external leads go out near the top.

[Kent King]

Now you can see the two pull posts mounted on the chassis. Remove the 8 screws holding the chassis.

I fashioned a puller from an old wire coat hanger: 

Hook the two ends into the pulling posts:

These pull HARD...you can work up a sweat getting the chassis out. Be careful to push in enough of the power cord to allow the chassis to move upward. Pull it at an angle away from the two large leads at the top too. 

[Kent King]

Finally, you have the chassis out where it can be recapped. These are hard to work on, you need to remove the components at the bottom of the chassis to remove the lower bakelite plate so you can replace the caps in the middle layer. Replace all caps and check resistors for tolerance.

Finally - TEST the unit before putting the chassis back in the case. You don't want to pull it again!

[Brad Winder]

THAT looks amazing, but a ton of work! How much alignment is needed to get it operating perfectly?

[Kent King]

There are no adjustments within the unit itself that you can't reach with the unit assembled. So if you check the resistors, replace caps and have good tubes, you will probably get good results. This particular unit works extremely well, it is in the Valencia set I recently purchased. As I said, these are a real pain to work on but do provide some great results.

Kent

[Don Jackson]

Hi, I am a new member here and recently acquired an Allwave 23 with a Tasman cabinet. I am not new to radio collecting, but this my first Scott. Radio was at an auction and was not in the cabinet, the components were in separate lots. In one of the lots the was a mysterious flat chrome box. At first I did not know what this thing was, and after looking through the archive found a picture of a volume expander so then at least knew what it was. It also became obvious what the hole in the side of the cabinet was for. Further searching in the archive provided a schematic and instructions. I had already gone through the AW23 chassis, replacing caps, rubber wire etc. and it now in good working order so I set to work on the volume expander.

To make the project all the more tedious all 3 cables had bare wires on the ends. I was able to make a plug out of some junk box parts, and extend the threads on a 500 k pot. I removed the top caps from a couple of old tubes and added grid caps. All of the wires had to be traced to figure out what they were for. Using the instructions that Kent King provided, I opened the unit and carefully replaced all capacitors and resistors. I tested the unit before putting it back in the box, and was very pleased with the results. I find that it does improve the sound, and also looks good mounted in the cabinet.

This was a very time consuming project, but would easier if I ever did another one.