My 153B Hepplewhite

[19&41]

I found my favorite Magnavox on Craigslist. The price was $50, tax deductible to the local breast cancer association. It was pretty dirty and had the odor of little rodenties living amongst the tubes and IF transformers. I balked at first, but then the husband of the couple offered to transport it to my house. Sold! I sat it in my living room and started taking stock of what I would need for it. I bought 2 resistor assortments, 2 electrolytic capacitor assortments and ran off copies of the necessary service guides. This console had one thing extra: a "record box set" containing an FM tuner covering the post-48 band configuration. After my items arrived, i put the resistors into plastic cases with divided compartments and unmounted the receiver from the cabinet and put it on the front porch to brush and blow off. I saw then some components that would need to be replaced due to P damage.
To Be Continued.

[electra225]

That's a mighty handsome instrument! The FM tuner makes it fairly rare for its day and time. I look forward to following the project.

[William]

I too am looking forward to the "rest of the story". Is the Magnavox you are referring to the one in your Avatar?

Bill

[19&41]

That's the one.

[electra225]

Do I remember your doing some work on it at some earlier time? Do you still have the little Magnavox stereo you were working on a couple (?) years ago or so?

[William]

I like the cabinet, the extra shelf area for records or other stuff. Your FM tuners is sitting on that shelf, correct? Behind a door? Except for the FM tuner, is the rest an all in one chassis, or is there a separate amp? I'll shut up now and wait for the "to be continued".

Bill

[19&41]

The "record case" is a metal cabinet holding a horizontally oriented FM tuner. The panel you see below it is a AM broadcast/ shortwave receiver with a 6L6 push/pull amp driving 2 10 inch field coil speakers

After getting the components together I started studying the chassis, trying to identify and correspond the components for replacement. There were a few problems. The chassis had a number of production modifications with components having been replaced, to include a few phenolic overmolded paper capacitors. They used the old color dot identification and between darkening, yellowing and fading, I couldn't identify their value as shown. SO, I made the investment in a capacitance meter and physically checked values as I pulled the old components to replace them with new. A few years back, I had purchased a D550 magnum soldering gun and it came in quite handy in the replacement of the multi section capacitors, attaching the new, smaller caps in obsequious areas under the chassis, soldered grounds directly to the chassis, leaving the old cans in place, undisturbed. I had given the tuning mechanism and the capacitor a good cleaning with 91% IPA, cleaning P stains from that area. I went through and made a cursory check of resistance values, replacing a few. At this point, I removed the speakers from the cabinet, to make sure there was no deterioration. When I got the radio, I had noticed a torn dimple in the grille cloth when purchasing it, I found it was the entry point for an arrow. There was a hole in the cone about 2 inches in diameter. I went to hobby lobby and got some assorted construction paper I then got some flowable silicone sealant and saturated a small piece of black paper with and applied it to the cone and fabricated a pretty nice lightweight patch. To Be Continued.

[William]

Thanks for continuing your restoration Rex. I look forward to part three.

Bill

[19&41]

While doing the restoration work, I found a reasonably priced RF signal generator that fit my budget. After putting the speakers back in place, and performing QC on the receiver/amp, I acquired a nice wooden TV table, just right to hold the boatanchor next to the cabinet and brought the unit slowly on my variac. It came up nicely, with just the good old P aroma. With the attachment of the loop antenna, it brought up some broadcast traffic. I started through the alignment steps and things went well until i got to a ceramic adjustable capacitor associated with the shortwave portion. It was positioned face up in a hole in line with a P stream. After finding it's value and examining it, I looked up and found 2 caps that appeared to be potential replacements, at the surplus center of Nebraska. They stock NOS pre-1965 replacement parts. I chose the closest dimensionally and installed it. That allowed me to continue the alignment, and I repeated it 3 times to make sure everything was tweeked and peeked. The unit had an old variety of audio input connection. I went ahead and replaced it with an RCA female bulkhead. Jumping ahead, I replaced the FM tuner's audio connector with an RCA female bulkhead Each of those allowed for the greatest flexibility in using audio devices as inputs for the unit. Having completed the alignment and a 3 hour burn in, I reinstalled the unit in the cabinet. I then began the FM tuner. It too was loaded with phenolic overmolded paper caps too. There had been 3 in production manufacturing changes, so a number of the capacitors were not even identified in the manufacturer's spec folder, so I had to use the capacitance meter to identify the components and replace each to the tie points not indicated in the layout. There were a number of roasty and toasty resistors in the tuning indicator circuit that I replaced. I pulled it's tuning scale window and cleaned it also. The alignment procedure given in the manual, printed in 1946, was interesting and effective, as FM signal generators were few and far between then. It is performed using an AM signal generator with an audio carrier. I went ahead and burned it in for 3 hours and realigned it. I finished things up on new years eve. The next morning, I turned on the unit, switched it to FM, turned on the FM receiver and tuned in the Vienna new years broadcast on PBS. It brought tears to my eyes. The clarity of the broadcast and the dead silent noise floor amazed me. I could hear tiny background sounds, like a step on the podium. All that from a 50 buck mouse house. I've burned a lot of the P smell from it. In the first 2 years of having it, I was able to bring in Radio Australia regularly til it signed off. I also was able to get a QSL from Radio New Zealand International. I set up a 50 ft wire antenna and an 8 ft ground stake tied to a coaxial feed into the house. I wanted a proper antenna like old times. It has been a fun toy.

[William]

Thanks for sharing Rex, you definitely spent a lot of time but it was well worth all your efforts.

Bill

[19&41]

Thanks,Bill!

[TC Chris]

Yeah, your project can inspire the rest of us! My '51 Maggie has those molded caps. It was giving some oscillation with the bass advanced last time it was on (20 years ago) so they have likely died just as quickly as if they had just been paper with wax. But your example shows it can be done.

Chris Campbell

[19&41]

Thanks Chris. I'd also like to recommend Sal's Capacitors, He had most of the caps I needed to get the job done, with fast service and a great selection.
http://www.tuberadios.com/capacitors/

[William]

I like Sal's too and buy most of my caps from him.

Bill