EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

1934 AW 15 Electrical Restoration, Questions Please

Hello all,

I am new to this forum and somewhat new to E.H. Scott Radios.  I have about 10 years experience collecting, restoring, and rebuilding pre WWII radio's back to factory specs., or as close as possible.  I am excited to start an electrical restoration on this early version AW15.  My goal is to re-stuff each and every bathtub style capacitor which will include drilling out each rivet and re-installing new rivets.  I will also re-stuff all electrolytic cans.  The end goal of this restoration is to have an electrically restored factory looking set.  

Has anyone re-stuffed these bathtub style caps before?  Could you please give me any pointers or advice for this procedure?  What style of rivets are used for re-installation and what would be the best tool to use for this as there will be many awkward angles?

You may notice the Olympian cabinet this radio resides in has short legs.  Upon close examination, Norman and myself have decided this cabinet had a new set of legs and stretcher installed at some point during the radio's life.  Whether at the beginning or sometime mid point, I don't know.  The legs and stretcher look to be a custom job and the quality shows as this modification looks to be neat and very difficult to spot upon preliminary inspection.

I would like to thank all of you for any help provided, this looks to be an excellent forum!

Thanks,

Jon

 

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Understand, thanks Norman.  Appreciate both of you telling me more about the AW-27.  Were all the cabinet styles sold by Scott at the time able to support the AW-27 chassis?

Jon

No. The power amplifier was longer, the speaker was larger, and headroom was required for the indicator tubes. I am aware of original AW-27 chassis in the Waverly, Warwick, Warrington, and Rivinia cabinets.

I have officially started on the AW-15 amp chassis.  Here are three pictures of it's current status before I dig in.  My goal on the amp chassis is to replace all capacitors as well as resistors.  I have already replaced the fuse holder with a fresh 3 amp 250v fast blow fuse.  I have also already replaced the AC line cord and power switch with brand new rayon parallel cord that matches the vintage of the receiver.

What do you think the black #611 stands for on the inside of the chassis?  Are all three electrolytic metal cans that sit on top of the chassis original?  The center one looks like a replacement, other two are matching with a green dot on the protruding post inside the chassis.

As stated prior, it has been decided to not re-stuff the capacitors within this project.  I plan on re-stuffing all capacitors and re-creating dog bone resistors on the AW-23 project down the road.

Thanks,

Jon

Attachments:

Agree - the middle filter is a replacement. The other two appear original.

The "611" is likely someone's tracking number - maybe a repair shop. 

Sets sent back to the Scott for service are noted by brown paper packing tape around a receive top side filter,  or perhaps around coil can. Amps are seen with a grease pencil marking inside with the same letter/number format as the receiver serial number tag, but usually not quite matching the receiver's serial number.

The original power switch had a long shank to accommodate the cabinet side thickness - hard switch to find now. I have had success rejuvenating  the old switch with spray switch cleaner and even soldering new wire to the old switch. A "tired" switch my present enough resistance to become noticeable warm so  try contact spray to improve it.

-Norman - thanks for the detail on AW-27 control info. Did not realize the BFO was deleted in the AW-27. The separate radio/phono switch took care of a shortcoming of the early AW-23 (my opinion) and a radio/phono did appear on the revised 7 knob AW-23  introduced January 1936. 

Thank you Norman.

Jon
 
Norman S Braithwaite said:

No. The power amplifier was longer, the speaker was larger, and headroom was required for the indicator tubes. I am aware of original AW-27 chassis in the Waverly, Warwick, Warrington, and Rivinia cabinets.

Dave;

Is the power switch a toggle switch with a long shank? I ran into that problem on the Philco 40-201 that I restored. It had an outboard toggle switch that was hidden in the grille area of the front of the radio pointing downward.  The old switch in the radio was arcing internally and getting hot. I just did not trust it any longer.

Joe

Joe,

You are correct.  This is the proper switch Dave is talking about and original to this AW-15 project I am working on.  I went ahead and worked it over with Deoxit D5, one example of a great contact cleaner.  I get proper continuity when manipulating the switch, should be good to go.  A good contact cleaner can usually solve intermitted switch problems.  The contact cleaner works to clean the corroded or oxide contacts.  I make sure after spraying to work the switch back and forth 50 times or so.  I had this issue with a 1929 Voxola I completed several weeks ago.  Toggle switch was dead, had no continuity.  After a spray of contact cleaner and working the switch back and forth, she worked fine.

Jon

Thank you Dave for your input and the info on the 611 number.  On top of the service number discovered, it is obvious someone did minor work on the amp chassis a long time ago.  I have yet to crack open the tuner chassis.  Do you think the speaker has been re-coned? (on the first page).  If it was, I commend the individual or company that performed the repair.  It's flawless workmanship.

Jon
 
David C. Poland said:

Agree - the middle filter is a replacement. The other two appear original.

The "611" is likely someone's tracking number - maybe a repair shop. 

Sets sent back to the Scott for service are noted by brown paper packing tape around a receive top side filter,  or perhaps around coil can. Amps are seen with a grease pencil marking inside with the same letter/number format as the receiver serial number tag, but usually not quite matching the receiver's serial number.

The original power switch had a long shank to accommodate the cabinet side thickness - hard switch to find now. I have had success rejuvenating  the old switch with spray switch cleaner and even soldering new wire to the old switch. A "tired" switch my present enough resistance to become noticeable warm so  try contact spray to improve it.

-Norman - thanks for the detail on AW-27 control info. Did not realize the BFO was deleted in the AW-27. The separate radio/phono switch took care of a shortcoming of the early AW-23 (my opinion) and a radio/phono did appear on the revised 7 knob AW-23  introduced January 1936. 

While studying the parts list of the AW-15 amp I noticed several discrepancies within the schematic regarding the amp chassis.  This AW-15 I am working on is an early version verified via the Wunderlich tube and antenna posts set up.  According to Riders volume 15, the schematic/parts list pictured above would be the early version.  All 8 components circled in white and red above are not labeled anywhere on the schematic.  Are there several revisions on the early versions?  Where would I find these changes that show the components in question?  It would seem the AW-15 info within the archive matches the schematic above.

I have already changed out several components, so this should not be a show stopper for me.  It would be a nice luxury to verify with the schematic though before the post-restoration power-up.

Thanks,

Jon

Jon -

The AW15 is quite probably the most unstable Scott chassis of all the models. Even in the late 1930s, Scott referred to Type I, II and III AW15 sets. I don't think that any two sets I've seen are identical, and I have probably a half-dozen chassis here at the moment. My recommendation: since the P/S is pretty simple, just sketch out what you have in your chassis and see if it makes sense. If the components are original (or appear so) and the resulting diagram seems reasonable, I'd try to operate it.

Kent

Jon,

For what it's worth, if you watch the video on youtube about making the aw15, you will notice that in one shot the chassis has the one cap and two filter setup like mine, in a later shot there are clearly four bathtub boxes fixed to the rear of the chassis, so this means that they were probably making changes on an almost daily basis,

not an easy thing to deal with eighty years on, use the circuit diagram and a pencil I think is the best method.

Mike

Thanks Kent.  I will double check my work.  The current placing of all resistors looks to be factory and it appears the two bathtub caps along the inside wall of the chassis do not go to ground.  I have already replaced all but both 2 watt resistors and capacitors, which is today's project.  I will do as you say, Mike might be helping out as well.

Jon
 
Kent King said:

Jon -

The AW15 is quite probably the most unstable Scott chassis of all the models. Even in the late 1930s, Scott referred to Type I, II and III AW15 sets. I don't think that any two sets I've seen are identical, and I have probably a half-dozen chassis here at the moment. My recommendation: since the P/S is pretty simple, just sketch out what you have in your chassis and see if it makes sense. If the components are original (or appear so) and the resulting diagram seems reasonable, I'd try to operate it.

Kent

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