The Fine Things are Always Hand Made
Good morning everyone,
This is my first time posting so please forgive me if I mess something up. I have recently purchased the radio stated in the subject line above and please see the attached pictures. Single tuner, Serial M-99, single speaker, and AVC with the Wunderlich tube. Before powering up the radio on a dim bulb tester, I notice the 80 rectifier tube was in one of the 45s' socket and the 45 was in the 80 socket. I decided I better start checking underneath the power supply before applying power. I noticed filter caps have been changed out in the past and some soldering on wires in different locations. I pulled the tubes out in the power supply and began tracing wiring and taking resistance measurements. The biggest GOTCHA so far is what I understand to be the audio interstage transformer. Please correct me if this is not the correct terminology. My Fluke meter shows an open circuit on all connections. I have never seen a transformer open like this. Anyway, I need a replacement. Performing research by looking at the grid and plate characteristics of the 45 and 56 tubes. I believe this transformer from Antique Electronic Supply could possibly work.
Any advice will be greatly appreciated letting me know if this part would work or I'm totally out in left field. I'm in and out of the house today so it may take time for me to respond.
Scott listed the ohms values of the primary and secondary sides of the transformer. This will probably work, so I would give it a try. Very unusual for both sides to be open, but I had to have a new power transformer built for my allwave 23 due to a shorted winding. Work done by Heyboer transformer co. in Grand Haven Mi. It took several months as they are a small company, may be worth a shot to see if they can rebuild or make a new one for you.
$150.00 for my new transformer is a very good price for a one off part.
Also, you can try to take the transformer apart and check the connections inside.
Good evening Thom,
Thank you for the reply. Yes, i plan to disassemble the unit in order to get lucky and find maybe several problems. You are correct on the unusual for both sides to be open. I checked several times and plan to check again once disconnected from the circuit. I believe some one may have moved tubes around which may have led to the demise of the transformer. I keep researching for more information concerning this chassis yet I only see schematics and not values. Do you know where I can find specific values on components such as this transformer? Thank you for the connection with Heyboer transformer. I believe I would have to know the specifications of the transformer before consulting with Heyboer.
Did you check on the files in the Scott Info Archive here? Click the link at the top of the page, go to Set Folders and Allwave Deluxe. I will check my supplies, I may have another AW12 interstage transformer laying around here. The transformer you listed will work quite well.
Advise you verify pin 6 of the set cable is not wired, the most commonly seen version.
The final version of the Allwave Deluxe AVC 12 tube had a revised audio path using pin 6 of the set cable plug.
The tube sockets should have the tube number embossed, except the Wunderlick socket just has a dark red center button.
Remember Scott was a custom set builder, and a model evolved with modifications during a production run, so your radio may not agree in every detail compared to the published circuit diagram. If you find a discrepancy, make a careful inspection to determine original workmanship.
You have the original speaker cloth.
Loose veneer on the front legs results from dragging the cabinet across carpet. Mine was missing some of the veneer, which is not too hard a repair being dark color.
Good luck with your restoration. Do replace the original caps with modern, except maybe the the larger bathtub type across the back apron which also have a coil inside.
Good evening Kent and David,
Kent, yes I did check the Scott info archive and unless I'm missing something, I only see the schematic diagrams from riders and alignment information. Thank you for checking your supplies and I appreciate you stating that the transformer I listed will work well. If I have no luck at fixing the existing unit and no luck acquiring a NOS unit, I was contemplating removing the guts from the existing unit and mounting the one I listed inside the metal box. Hello David, pin 6 is vacant and I did see somewhat of a red dot on the center metal part of the tube socket. All other sockets have the tube numbers. I assume the speaker cloth is original, I have the original speaker, and I temporarily placed fish paper around the veneer held on by packing tape. The objective here is to keep the veneer from pulling off of the wood until I can have the cabinet restored. At one time, what i claim as shiny varnish was sprayed all of the face and cabinet with RUNS. I have someone who custom builds furniture and cabinets and would be great with the restoration of this cabinet. It will not be cheap. I do plan to replace the caps in the power supply. The large outside cans have seen better days with dents and aftermarket replacements. On the subject of the large bathtub type on the back apron with an installed coil, what is your experience with the fix for these caps. Can you disassemble the bathtub and replace the cap without damaging the coil or are they okay to leave alone? I have attached pictures of my poor capacitors and the speaker front and back. What is the round circle on the front of the board? Another strange thing. The speaker and wooden board that is attached to the speaker was never hard mounted to the cabinet. It practically fell out during the disassembly process. Thank you for the luck with the restoration. I will be posting for awhile with many questions for the professionals. IMG_1235.jpgIMG_1236.jpgIMG_1237.jpg
I did not rebuild the bathtub caps on the back apron of my AW-12 AVC. Otherwise it is extensively recapped and works great. A very sensitive radio with very decent sound for the era. The dial lamp also projects the tiny pointer of the tuning meter onto the dial strip.
Your old filter caps should be left for appearance sake when you hide modern electrolytic in the amp. I would remove the Aerovox labels. Then polish the filter caps with Mothers Mag Polish (auto parts dept of most stores) as the aluminum will shine up almost like chrome. Your radio likely dates from sometime 1933 as the special Jensen pedestal speaker was Scott's Spring 1933 speaker upgrade, replacing the twin speaker set used since mid 1932.
The round 12 inch violin like device mounted on the front of the speaker board is a Tauscher Sound Board, offered by Scott starting about 1940. Should have been mounted between the speaker and cabinet speaker board. I have both 12 inch and 15 inch versions but do not use them as I would expect it to muffle the sound a bit.
My Napier cabinet also had a rough history including a varnish/shellac coat with runs which I smoothed out with a scraper before brushing several coats of thinned shellac, followed by fine sandpaper, then rubbing compound for a near piano finish.
Good Luck on your restoration.
Since I gather this is your first Scott restoration - schematics are guidelines when working with Scott sets. As a custom builder, sets were constantly changing and they did not update schematics very often. There are variations of the AW12, not as many as other models, but treat the diagram as a guide only, not as the law. If you encounter a circuit area that doesn't match, draw it out. If it makes sense, it may be right - I look at solder joints and other clues to see if it looks "factory" or not. I've encountered two variations in my last 3 restorations, and I'm not far enough into the 3rd to say I won't find another one!
Thank you David and Kent for the prompt and wonderful replies. I plan to keep the capacitors top side on the power supply and was thinking about rebuilding them as I have had success on other electrolytic capacitors on other radios. I have had success on rebuilding the bathtub caps (without coils) on one of my 800B6 units with three more to go plus my allwave 23. All are strictly chassis units and hope to track down cabinets for them in the future. I thought I was going nuts because I could not track down resistor or capacitor values. I took the schematic files to Staples and had them blown up so I could read them. Comes with age 54. Anyway, great ideas gentleman. I plan to pull the inter stage transformer out and verify open circuits on both coils. If so I will attempt to track down a NOS part or pull the guts out of the metal box and mount the newer unit shown in my link. I will update when progress is made and look forward to your comments. Have a great week.
I'll try to check today to see if I have an interstage transformer for the AW12. I also see this is not your first Scott restoration, sounds like you have several. You are right, all windings open is very unusual. I strongly recommend going over every wire in that amp, get it back to what it should be! I'll let you know if I find an extra transformer.
I do have a transformer, PM me if you are interested and we will work something out.
Good evening everyone! Kent, message sent. I cannot wait to respond later with more updates. Have a great evening.
Good evening everyone,
Well responding sooner than expected. Thank you Kent for the help with the transformer. Next issue is the field coil section of the speaker. It is open. So far, other sections of the speaker assembly seem to be okay or not open except for the field coil section. Does anyone know where I can ship this coil to be rebuilt? I see several places on the WEB who perform speaker rebuilding but I want to get everyone's opinion of who they may have used in the past with great results. All I need is to have this coil rebuilt. Thanks again. IMG_1252.jpgIMG_1253.jpg