AW23 Power supply rebuild

[John Perry]

Greetings

Anyone know if I should replace the 4 .13 @200 paper caps with .047. It was recommended to use .047

to replace all paper caps on the AW23 rebuild. Does that include the power supply as well?

On my tuner most were already .05 but there was 2-3 that were .1. Connected to the pots I think. 

Thanks

John

[Thomas Day]

John:

When i rebuilt my first Allwave 23 I followed the schematic and replaced caps with .1 uf 600volt.  Except for the few that were .05.  I am working on a second Allwave 23 and replacing the caps with the values I find when I take the old ones out. This is a mix of .1 and .047.  I have a couple of resistor values (250K) that do not seem to be available now, so 247K to replace those. The originals are +/- 20%, so 3K shouldn't make much difference.  I am also replacing all the rubber covered wire, which is crumbling.  I found a company that sells this in 10foot lengths in both black and red. BTNECHGO. It is available in 18, 20, 22, and 24 gauge. $6.00 for two 10 foot lengths.  For the power supply, you should find either a single two section .25 1000 volt cap or 1600 volt caps.  My first radio had a bad power transformer which I was able to replace thru Heyboer transfomer co. in Grand Haven Mi.  I do not have a power supply or speaker for the second chassis, so will improvise.  One other point, there are .047 bypass caps on the filament leads of the oscilator tube. My early chassis did not have these, so I will add them at some point.  This later chassis does have them.  This is a pretty easy chassis to restore and well worth the results.

Thom

[John Perry]

Thom

I usually do 40s and 50s radios. This is only my 2nd 30s radio. Except for a Stromberg Carlson 225h I restored. I like the Scott AW23. Cant wait to get it powered up.

Thanks for your good input.

John

[Norman S Braithwaite]

The 0.13 mfd capacitors are part of a 10-khz filter.  Changing the value of these will change the frequency of the filter.  The filter was included to prevent the carrier of an adjacent station from causing a whistle when listening to experimental AM high fidelity stations, a feature that is practically useless today.  I know of one fellow who simply removes the entire filter.

Norman 

[John Perry]

Good to know thanks  Norman

[Kent King]

I'm going to add a VERY unusual problem I encountered today with an AW23. The set was playing well after recapping and alignment, except...every once in awhile, the dial light and all the tuner tube filaments would go dark. Usually after it ran a couple minutes, and when it "cooled", it would turn on again. But not every time - and I tried it on a couple amps, same result. So I concluded it had to be at the set end. Looked very closely at the set connector that plugs into the amp - and one of the two filament pins looks like it may be a cold joint. Wiggle a bit and sure enough, the one filament wire is loose in the pin. A careful resoldering resolved the winking filament problem. I've seen cold joints in Scott sets before, but never on a filament pin on the plug.

[John Perry]

Good info thanks. Are all of the AW23 Power supplies interchangeable? I have a Q458 and an N535 serial no.

Im rebuilding the 458 now. Im trying to decide if I should do some re-stuffing or just mount new parts where I can.

Curious to see how others did it. There is sure a lot of room in that double .25 black can. I do think I will re-stuff the double .01 input power caps mounted on the side with some new safety caps and remount. Also I pulled the 5mf sideways screw in can.

Think i will mount a terminal strip there. And use that for the new 5 mf and the 2 .25 @1250 caps.

John

[Kent King]

John - Yes, the AW23 sets are all the same, the power supplies are interchangeable. The set pins just need the 250v B+, the 20V bias voltage, ground, 6v filament and the two output Plate returns. That's the 7 pins...

Kent

[David C. Poland]

John, regarding rebuilding the dual .25 mfd unit ahead of the the 10 and 30 Henry chokes in the amp, be sure to use high voltage caps. 630 volts is not NOT high  enough. Scott used 1250 volts caps here in the dual unit. I suggest higher, upwards of 1500 or even 2000 volts depending on what is available.

[John Perry]

   OK thanks David