all wave 15 question

[douglas wright]

Happy new year to all, my first question is the volume control, i have a pictorial of the underside of the chassis, it shows the volume control to be a dual 500k volume and 700-ohm gain control. my chassis has only a single volume control, which I need to take apart, it is hard to turn. is it supposed to be a dual control? the schematic from riders does not show the gain control that I can see.

second question, the tuning indicator, if it is defective, will it affect the performance of the set?

the operator's manual says to remove the leads from the screw terminal and bridge with a wire, if it fails to function.

[David C. Poland]

Scott made a number of changes as the model evolved. If a vintage control, probably correct. 

The dual control was short lived variation. As was an additional outboard switch for static.

You may need to refer to more than one diagram to deal with your particular radio.

We have 5 diagrams from April 1934  to 1935. Some years ago several of us documented 7 variations among us just by comparing tubes line up, static switch variations, type of tone control, etc. Early sets used the Wunderlich tube for second detector with a center tapped secondary on the last IF secondary, later the 55 tube in a more standard circuit. Scott was a custom set builder.

[Kent King]

If your meter is bad, it will not impact performance of the set. I have to admit, I had not read the manual about bridging the terminal connections with a wire. If you did that on an AW23, it would burn out a resistor underneath - but the circuit in the AW23 is different. I would not worry about bridging or anything, just leave the meter in place as is.

Kent

[Alex R. Whitaker]

There's plenty of parts sets for AW-15s out there.  If your meter checks bad, you should be able to get a replacement fairly easy. 

[Kent King]

Well...I am perpetually short of tuning meters - many are bad and I have no spares at present, in spite of all the parts chassis I have.

Kent

Alex R. Whitaker said:

There's plenty of parts sets for AW-15s out there.  If your meter checks bad, you should be able to get a replacement fairly easy. 

[David C. Poland]

I had one that appeared bad, but it was a broken wire. It had corroded at old terminal.

Was able to tease out the end of the very fine wire and solder a short extension to bridge to the terminal strip.

I believe the AW-12 15 & 23 used the same movement, although the stalk varied a bit.

[douglas wright]

Sorry guys, I have a another question, 

The 3 blade switch in the can behind the drum dial,

Can someone post a picture if it in the broadcast band(white dot).

Mine was bent, I took apart to straighten the middle blade, now I don't think it is correct,  in broadcast band it is not making contact with the blade closest to drum dial.

Sorry for the questions,  this is my first scott to restore. 

The picture below is after the switch was put back together and reinstalled in radio.

[douglas wright]

[Kent King]

Here is my AW15 in AM position. Looks like you need to flip the little wafer over (180 deg out)

Kent

douglas wright said:

[David C. Poland]

Hence the reason to 1) put the band switch in Broadcast position before dismounting the coil wheel and 2) not moving the band switch until the coil wheel is re-installed. Protects the switch seen in your photo.

That little fibre cam under that hex nut operates switch pictured. If the band switch is moved when the coil wheel is off, then there is substantial risk of moving the cam shaft 180 degrees off in re-mounting the coil wheel. The result the band switch feels stiff or stuck ... and forcing will bend switch leaves, damage to the fibre cam that operates the switch or both.

A real pain to be confronted with damage from older service attempts. Being hidden inside the antenna coil cover, it is not obvious the switch exists and that it is operated by the band switch unless the tech info has been carefully read.

[David C. Poland]

Here is my AW-15 switch. The middle leaf of the switch has a leg that rides on the fibre cam.

Photo is in broadcast position and the contact is to the outer leaf, towards the tuning dial.

Turning the band switch moves the cam counter clockwise pushing the middle leaf towards the antenna coil to the other contact for the SW bands.

If the cam is reversed, trying to turn the band switch would jam the cam into the wall of the cup that secures the big cover. Or if the cam shaft is 180 degrees wrong then the cam may turn such that the cam indent hangs up on the leg of the middle switch leaf either damaging the fibre cam, bending the middle switch leaf, or both.

IMG_0980.jpeg

[Norman S Braithwaite]

There are two possibilities that can result in the 180-degree misalignment above the chassis.  One is that the phenolic wafer was removed and replaced out of phase and the other is that the bandswitch was rotated.  The former is more likely but the cause must be determined and properly corrected in order for the antenna switch located immediately behind the front apron of the chassis to be in the correct position.

Norman 

[douglas wright]

The band change lever is in the broadcast  position need a little more help, I believe someone before me must have removed coil wheel, in the photo which one is the broadcast band coil?