AW23 Tuner rebuild.

[John Perry]

Hello all
I am picking back up on on a project from a while back
I have a Tasman fully populated with tweeters S#N535
An extra tuner,PS and speaker S#Q458
I am rebuilding tuner Q458 first.
Pulled the antenna coil to replace the rotor area wiring.
The inner coil with the 2 fine wires fell out of the tube. It tugged on them a bit but they didnt break.
I put a small piece of painters tape on the sides of the wooden plug and shoved in back in the large coil tube.
It fits in snug now. It ohms out at around 50 ohms for the inner coil. Hopefully thats OK.
One question on the N535 is the large coil tube trimmer behind the large tuning condenser.(fig 3 Part 296) Is missing the screw on the trimmer and bent wide open. Anyone seen this before? Dont know if it was done at the factory or tweaked for some reason.
Thanks John

[John Perry]

Thanks David for the input. I had oxidation and wasn't getting good continuity. I lightly cleaned with a fiberglass pencil. Dont think I removed much. If I had to I could re-plate the silver. Hopefully its OK. There is a wear line on the wiper at the point it goes in between the pinch contacts. I hope there is enough silver still left since that is the main point of contact.

My worst fear is braking the contacts so far Im OK.

[David C. Poland]

Yes  -replacing all those receiver caps with .047 caps at 600 (or today, 630 volts) is correct for an AW-23. Scott switched to 600 volt .05 caps sometime in 1936 production. There is a Scott service bulletin during any service to replace the original 400 volt .05 caps of earlier production sets with 600 volt caps.

Treat the coil wheel floating contacts with great care!! They are silver plated and Scott instructions say clean with alcohol. You do not want to risk contact surface damage with any kind of abrasive!!

[John Perry]

Hi Scott

Yes that sounds reasonable. Not sure how it will act after a rebuild. Also All my wax/paper caps are being replaced/upgraded with  .047s Not sure what effect that will have on the trimmers.

John

[Scott Seickel]

I have an AW23 that has the trimmer screw missing and it is bent open.  I have not worked on it yet, but I'll bet that they needed to lower the capacitance more than the screw adjustment would allow. 

[John Perry]

Antenna rotor contacts.

Some of my contacts are not getting much movement or none are the wiper goes through. Same with the ball that wipes across the bottoms. I am making small adjustments being very careful. I am happy with how it is now except one contact has quite a bit of flex as the wiper goes through. maybe a little over a 16th on the questionable one.

Any thought on how much the contacts should move as they are engaged. My thought is just a noticeable movement  like maybe a 32nd of an inch. I have cleaned the contacts and wiper with a fiberglass pencil. And then DeOxit F5

[John Perry]

Thanks for the info
Dont see any other paperwork inside but that sounds about right.
There is a notice sticker on the bottom plate (English,Spanish and French)as well . Its says it was calibrated at the factory and if removed warranty would be void and you would be charged a whopping $2.50 per hr labor fee.
It has pencil writing at the top of the sticker says Dec 10-38 -R.62
Ill check the manual on the tweeter plug.
John

[Kent King]

John -

You can run them without tweeters, but be sure to move the "dummy" speaker plug to the opposite side of the speaker base. The plug adds a resistive load when the tweeters are not used. Leaving it on the "tweeter" side will cause problems. Do not run the power supply unloaded, all 3 pieces need to be cabled together to keep voltages and such from going too high. 

The date and notation sound like a service visit to the factory, 8578 might be the invoice or tracking  number for the repair. Is there a band of paper around one of the tube shields on the tuner? (or was there?). That was commonly done to track repairs internally. I leave the paper bands on my sets - part of the history, it went back in for service. 

If you need info about running the speaker without tweeters, the manuals in the Scott Info Archive cover it.

Kent

[John Perry]

Thanks Kent
Interesting thing the N535 Has writing in pencil on the bottom of the tuner pan
3/24/1937 N-535 then underlined 8578 not sure if thats from a tech or factory
Sounds like it was later.
Also do you know if its OK to test the unit without the tweeters.
I would like to test the PS as well but assume it needs the tuner and speaker load.
Thanks John

[Kent King]

John -

I had the same thing happen on an AW15 I worked on not too long ago. The inner coil fell out of the outer coil. Like you, I put it back into the tube and secured it, set restored just fine. Regarding the trimmer being wide open - I haven't seen that before, but if the set works well, I wouldn't worry about it. 

I appreciate the serial numbers, both are new to me. I have a good date on N-537 - Mar 23, 1936, so that gives you a very close date for your N-535 set.

Kent