Need help...Scott Allwave 12 manual and schematic

[Mark Kaplan]

Hi all,

I'm very fortunate to have acquired a Scott Allwave 12 in decent shape.  I believe it is  a "transitional " model.  It has one dial, two speakers,  three 58 tubes and a Wunderlich tube for the detector.

I did find one schematic online but it doesn't seem to match my set.  In particular, the large power resistor (voltage divider?) mounted to the side of the chassis doesn't match .  There are five taps on this large power resistor.   Tap closest to front of chassis is ground.

The other sections read: 1080, 600, 1180 and 4300 ohms respectively.

I really really need a schematic which shows the values of the parts (resistors and capacitors) and possibly a manual.   An electronic scan would be super and I can print it out.

I've posted a few photos of the set.

Someone has removed all the wiring from the original electrolytic caps and there are a few new caps tacked in  various places and two or three other replacement capacitors but pretty much things look original.

I would appreciate any help or advice that can be provided.

[mike hadley]

Mark;
I have been thinking about your problem and maybe stating the obvious, to check cathode bypass caps and resistors on the output stage, but It looks like you have already done this,
On the restoration of my aw15 I had a peculiar fault that on short wave bands, there was a hiss like untuned fm between stations, but quiet when tuned in,
turns out that I had an intermittent 58 tube, checked ok in the tube tester, but a gentle tap with the handle of a screwdriver proved otherwise.
glad to see you're getting there, it looks like you don't have far to go now
Mike

[Norman S Braithwaite]

A little gas in the tube, perhaps to little to observe, can drag B+ down a lot.

Norman

[Mark Kaplan]

Norm,  I now realize that I did NOT check the two original 56 tubes for gas, just for shorts and quality.  The ones I substituted (which are now working fine) are two that I just got from you.   So thank you again.

Tomorrow I will try to tackle alignment of this beast.  It looks like there are four adjustable IF transformers with the last one being a bit different than the others.  I believe the IF frequency is about 465-470KHz although I'm not sure exactly where to inject the signal on this set....maybe at the first detector (57 tube) grid or the 1st IF grid?

This should be fun...

Mark

[Norman S Braithwaite]

Try the first detector grid. If you inject the signal to the first IF amplifier tube, you will not be able to align the first IF transformer.

[David C. Poland]

May not need alignment. See how it plays and tunes first before  trying to improve alignment.

And see if you can determine the current IF frequency by identifying what frequency it passes.

Do follow the instructions in the Scott tech instructions available in the SCOTT DELUXE set folder in archives.

Note - you need to have a coil can in place for each IF you want to try peaking. I drilled a 1/2 inch hole on the top of a rough  corroded  Scott coil  can that would press fit in position.

Consider starting with the 4 th IF and work towards the 1st IF. 

*

Incidentally, the Factory tech info says the long wire antenna including lead -in should be no longer the 75 feet, otherwise the set may tune too broadly (poor selectivity). 

Also note that in the cabinet, to minimize hum, place the amp to the left of the speaker(s)as you face the back of the cabinet.