1934 AW 15 Electrical Restoration, Questions Please

[Jon Ketron]

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

 

[Joseph W Strickland]

Jon;

That is a beautiful cabinet. The finish looks pristine from what the photographs show. I suppose it is possible that the customer may have had the legs replaced with shorter ones, however it may have been a custom one-off unit at the customer's request. We may never know. Do you have any of the original owner's documentation?

Joe

[Joseph W Strickland]

Jon;

I have an 800B model that I am in the process of restoring. It also had bathtub capacitors in it. All but one were the typical wax paper & foil types embedded in more wax within the enclosure. There was one oil-filled capacitor in the FM IF/Audio Output/Power Supply chassis. David Poland here mentioned that he used a dremel tool to cut into the capacitor from its bottom side and then removed the old parts and installed new ones. That is the method I used and it worked well. I did discover that someone had apparently repaired a single one earlier by using either a large soldering iron to remove the bottom cover and then resoldered it or may have used a small propane torch. That one had some burned discoloration on its sides. I did not want to destroy the printed part number and capacitance values etc. on the outside, so I used David's method.

Your set likely uses the dog- bone resistors in many areas. Mike Hadley in this group recently posted some details on how he encapsulated modern resistors in a workshop created set of molds and then paints the body and adds the needed end color or dots to duplicate the OEM appearance. If you contact him I imagine he can fill you in on the details of just how he made the molds etc.

Joe

[Jon Ketron]

Hello Joe.  Thank you for the reply and appreciate your comments on the cabinet.  The original finish has been very well persevered all these years, a feature difficult to come across on sets of this vintage.  The leg job is so well done, I though it was original when I first looked it over.  Very difficult to tell.  I am afraid I do not have any original documentation.

Jon

[Jon Ketron]

Joe,

Thanks for the tips on the bathtub caps.  As to the dogbone resistors, I have come across many in my restorations and have seen several methods on how to re-create them.  I have read the posting by Mike Hadley, excellent results!  I will perform this feat on this restoration.

Thanks,

Jon

[David C. Poland]

More than one highboy and lowboy cabinet was evidently dragged one time too many. I have an early Warrington highboy missing the Queen Ann legs (sawed off sometime past). I bought it for the nice 2-DIAL chassis. I knocked the damaged cabinet apart for transport - it is possible to buy Queen Ann legs in 3 heights, so maybe some day I may try a rebuild, taking measurements from my good example.

Dragging cabinets on carpet can also rip off veneer - Today, I use sliders if dealing with carpet.

[Jon Ketron]

Hi David,

Thank you for your input.  I too use carpet sliders for all my consoles.

Jon

[mike hadley]

Hi Jon

Be careful with the bathtubs and don't get them too hot, I used soderwick to get the backs off, inside the cap is made from foil paper and pitch, getting the pitch too hot will make it stick and more difficult to get the contents out, when putting them back together you only need to solder the corners, good luck finding rivets, I ended up using pop rivets,

I used Polypropylene caps in mine, good esr, low noise and very stable,

motor run caps are superb for the main smoothing caps, you can rate them at 1.5x their ac value when running on dc.

I found an item on dogbone resistors the other day, worth a look.

Mike

[Joseph W Strickland]

Mike;

I agree about the motor run caps for the B+ smoothing. The new polypropylene metal film types are excellent choices and as you mentioned the DC voltage rating is higher than the actual AC voltage rating. I used a 16uF cap rated at 470VAC that I bought through Allied Radio and it works fine in my 800B. It does raise the DC voltage by about 22VDC. One thing I discovered by doing so is that what residual hum I was hearing from the speaker was gone with the 16uF in parallel with an existing 4uF cap. I had already done the tone control modification on my 800B which reduced its tendency to have 60Hz induced hum.  20uF is a common input capacitor value on many products using 5U4 tubes as their rectifier tubes.

I dealt with the wax/tarry substance in a Philco I restored and to get the residue out of the case, I used some mineral spirits to soak the shell in and it dissolved the rest of the substance so that it made a complete clean-out easy. It was squeaky clean when I installed the replacement capacitors.

I would love to hear from someone who has found and used the right kind and size of rivets for the capacitors and tube sockets etc. in these radios. In particular, what kind of tools and techniques are used to install them.

Good luck Jon!

Joe

[Jon Ketron]

Mike,

Thanks for the pointers, I will use them for this restoration.  Did Scott use oil filled bathtub caps on a regular basis?  Are the oil filled type common on these sets?  I imagine you just used a common drill tool to drill out each rivet?  Could you please share more on the dogbone procedure?  Polypropylene caps are great to use and the only kind I use on electrical restorations.  I will most likely go with Sprague brand orange drops on this restoration since all caps are of the bathtub style.

Thanks for your response,

Jon
 

[Jon Ketron]

Joe,

I have had the same great results when using mineral spirits to clear the tar on Philco Bakelite capacitor boxes.  Thank you for sharing how Polypropylene's have helped on your current restoration project.  As to the rivets, I had seen a picture of Norman's Scott Special restoration.  In one of his pictures he had mentioned the correct style of rivets were used upon re-assembly after his chassis was re-chromed.  I hope he comes across this thread and shares more on his procedure.

Jon

[mike hadley]

Hi Jon

The caps are not oil filled as far as I'm aware, the 8uf smoothing caps in my set were foil and wax paper, bathtubs paper and pitch.

The cases of my smoothing caps were badly damaged and I had to resort to modern cap cases salvaged from my works scrap, restuffed with new caps, nice thing is they look original but have no markings,

next time i'm working on the set, (I have only owned for about 6 weeks) I will post a few images of these with the process I used to make them,

Nice to see you have a Jensen speaker with an early cast basket, I had to make a new voice coil and recone for mine, well worth the effort, there are a few posted images of this.

Mike

Jon Ketron said:

Mike,

Thanks for the pointers, I will use them for this restoration.  Did Scott use oil filled bathtub caps on a regular basis?  Are the oil filled type common on these sets?  I imagine you just used a common drill tool to drill out each rivet?  Could you please share more on the dogbone procedure?  Polypropylene caps are great to use and the only kind I use on electrical restorations.  I will most likely go with Sprague brand orange drops on this restoration since all caps are of the bathtub style.

Thanks for your response,

Jon
 

[Jon Ketron]

Mike,

Thank you for your comments.  I appreciate the help on the bathtub cap information.  Looks like all electrolytic capacitors are still present with their original cans.  Someone has performed electrical work in the amplifier sometime during the past.  I will post more pictures of the chassis and underside as soon as I can get this set up on the bench.  I also read your excerpt on the resistor method.  Very nice, I will have to try this method.

Jon