Thursday, December 6, 2018

The Trans-Oceanic Project

If you're reading this, there's a pretty good chance that you've got a soft spot for Commander MacDonald's baby: The Zenith Trans-Oceanic.  I certainly do: When I was about eight years old, my family took holiday at a cabin on Hubbard Lake in rural Northern Michigan.  At that time, there were no TV stations covering that portion of the state, but the cabin came equipped with a glorious model G500 Trans-Oceanic, and the sounds that came from it made enough of an impression on my pre-adolescent psyche that I became obsessed by all things electronic.  Eventually, this hobby became a career in radio from which I recently retired after close to 40 years.  Soft spot indeed.

Earlier this month, while on vacation in Florida with my wife and friends, I came across this very neglected model G500 at an antique festival.  The picture above really doesn't do it justice - this thing was totally trashed; the famed "Black Stag" covering was torn in several places and appeared to have been gnawed on by mice, as had some of the wiring.  The hinges for the rear panel had rusted completely through, the cover being held in place only by the rusted spring clips.  And the smell... Trans-Oceanics have a unique, friendly aroma, but this was a different fragrance: Mildew, rotted wood and mouse pee. 

But, the set appeared complete, including the coveted 1L6 converter tube, and the seller was willing to deal, so we agreed on a very low price (a fraction of what the airline charged me to check it as baggage) and the derelict became mine.

Things didn't get any better when I returned home and got the set on the bench and found that someone who should not be allowed anywhere near a soldering iron had attempted to repair the radio.  The underside was covered in soot; the power-supply section had lost its magic smoke in a big way.  My heart sank thinking about the rather delicate 1.5v tube filaments.  Had they also been damaged?    If so, my equity in this set would be in the red.

Fortunately, when I measured across the filament string, I got a nice, low resistance.  Holy crap, had the tubes survived?  I had to know!  So, I started undoing the previous work to see what all was wrong.  

My theory is that someone attacked the set based on "internet knowledge" that says selenium rectifiers are ticking time bombs, but without the understanding of what the rectifier does or how to replace it.  Equipped with this lack of knowledge, they bypassed the selenium with a silicon diode.  That probably went OK, but things went awry when they got to the filter capacitors... I'm not sure exactly what went wrong, but it's obvious that something was dead-shorted to ground at the input to the "candohm" resistor, vaporizing the diode and dropping resistor but not damaging anything else.  So, while it must've gone up in a glorious shower of sparks and smoke, the carnage was surprisingly minor.

Ironically, the selenium rectifier checked good, so the carnage was totally unnecessary.

Carnage removed.

New parts, including 1N4007 diode, mounted to added terminal strip.
Once the damage had been, um, rectified, the rest of the electrical restoration was uneventful.  The electrolytic and "Bumble Bee" capacitors were all replaced, as was the 3V4 audio tube, and the set roared to life.  Success!

But, cosmetically, the radio was a mess, and the only way to deal with it was going to be to strip it of it's upholstery, repair the damage, and recover it with new Tolex.  I wasn't looking forward to this part; I've seen reupholstered TOs before and you could immediately tell that they weren't original by the grain of the Tolex.  So, I scoured the web until I found a pattern that, at least in the photos, looked passable, so I ordered a couple of yards of "Black Bronco" from Parts Express.  When it arrived (in a very large box!), I was stunned - it was nearly a perfect match!

Thus, I set about the task at hand, photo-documenting every flap and fold of the old material as I removed it, and using each piece as a pattern from which the new pieces were cut.  Then, each piece was reinstalled exactly as the original had been by the factory.  Well, all but one - I goofed.  Still, it looks OK so I may leave it.

In addition to replacing the fabric, I polished and relacquered all the brass bits and installed a replacement dial lens (from Mark Palmquist - Excellent!), gave the set a final alignment and buttoned it all up.  

 Was it worth the effort?  Not economically, but I can't put a price on the rewarding feeling I got from bringing this beauty back from the brink. 

I'm still as enamored by these radios as I was back in 1970, they really are fantastic pieces of radio history.  It's unfortunate that so many international broadcasters have abandoned shortwave, but there's still a lot to tune in and nothing better to do it with than a Zenith Trans-Oceanic.

For anyone interested in learning about these sets, I highly recommend Bryant and Cones' book The Zenith Trans-Oceanic: The Royalty of Radios  from Schiffer Publishing.  It may be out of print, I don't know, but used copies are readily available through Amazon.  But please, don't be like the previous owner and attempt to service your TO without understanding what you're doing!

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