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;

Glad you managed to get the unit operational again. You do very neat work. The underside of the chassis looks very nice and neat. Like Mike, I approve of your original appearing resistors. It looks like a well preserved original, except for the few orange drop capacitors. Even the orange drop capacitors have been around since the 1950s.

Congratulations on a job well done!

Joe

[Jon Ketron]

Joe,

Thank you for the comments.  All tuner chassis dog bone resistor's are Scott originals testing between 10%-20% tolerance.  The only resistors changed were all located within the power supply.  My plan was to originally "re-stuff" and replicate everything.  It was decided early on to drop this idea.  Mike's chassis contains reproduction dog bones, they are done very well.  Thank you for the comment on the neat work.

Jon

[mike hadley]

Jon;

I have attached the method we use for cap testing, it allows for the slow application of dc and the whole thing is current limited by the lamps, there is also the facility to over volt the cap, this is a particular nasty thing to do to the cap but does provide the ultimate test if you like, do not exceed more than 10% higher than the working voltage when doing this otherwise the cap will act like a giant zener and may not recover.

the setup also allows for reforming if you wish to do that sort of thing, but I have never had much luck doing this.

all of the values are guestimated for uk mains, you will have to adjust values for your supply,

mind the fingers and have fun.

Mike

[Joseph W Strickland]

Mike;

Thanks for that information. It would be nice to combine that with one of the older capacitor testers made in the days of vacuum tubes, such as the ones by Eico and Heathkit with an eye-tube and variable control to measure the capacitance of the electrolytic under test. Some of those also had test ranges for film type coupling and bypass capacitors too.

Joe

[mike hadley]

Joe;

I forgot to include a scope across the cap under test to measure ripple,

half wave rectification is used as it gives far more ripple current than full wave,

this gives a better idea of the internal condition of the cap

Mike

[Jon Ketron]

Thank you Mike for the information and schematic.

Jon

[Jon Ketron]

I want to thank all members who were able to help with this restoration.  This AW-15 has been delivered back to the customer.  He is very thrilled to have the unit playing again.

I hope to have another E.H. Scott surface soon! 

Thanks,

Jon