I was watching Firefly the other day, and noticed something interesting. Firefly is set in the year 2517 centered around a small smuggling ship named Serenity manned by a crew of mercenaries, former freedom fighters, a pair of escaped convicts, a high class prostitute, and a comparatively normal mechanic and pilot. On one of their adventures in the second episode of the series titled “The Train Job”, space gangster Niska contracts the crew to rob medical supplies from a train. In the background of his office, you’ll notice something interesting:

In the lower left corner of the frame, you’ll see a 1940 Zenith model 10-S-464. It looks like it’s in good shape for being 577 years old, too. I wonder if there are any tubes left.

I thought I’d start the weekend off with some more photos of butchered antique radios for your viewing misery pleasure. This is the second-round photo roundup. Check out the first set of ruined antiques here!

An aspiring artist thought this 1940s Philco radio would look better painted in a motif reminiscent of Starry Night. I don’t really agree.

Somewhat similar, a dealer is selling a Zenith tombstone radio that’s been decoupaged with magazine clippings. This was almost an interesting work of art, but because the magazine clippings aren’t from the correct period, it’s just tacky.

This late ’20s lowboy radio was stripped down into an end table. Cleanly done but it would’ve been more interesting with the internals, even non-working.

From Craigslist, someone turned what I suspect is a late ’30s RCA into a bar with a modern stereo built in. Turning radios into bars seems to be a popular thing to do with them.

Radio bar conversions have been going on for a very long time – almost as long as radios have been around – and some can be very interesting. It’s just that many are done without respect for what the radio used to be – and without regard for the shape of the cabinet. Most upright radios don’t have a flat inside space to place anything, making shelving difficult – and ensuring that it’s going to look ugly no matter where it’s stored.

Most similar-looking Post-War consoles with a record player are reasonably suitable for conversions. This one has been adapted into a cigar bar:

That’s not too bad, but radios with more square space inside are even better:

I’ll be converting one in this style to a bar myself, soon:

Back in the 1930s, radiobars were intricate pieces of high-end furniture in custom made cabinets for the wealthy and were produced by several major brands. This 1937 Philco radiobar has great folding out sides and mirrored backing, with period glassware:

They came in a few cabinet styles:

There were even models produced into the ’40s and ’50s, like this Porto-Baradio mantle-top bar:

If you’re looking for an antique radio bar, you might be better off shelling out for an authentic one rather than a conversion.

And finally, leaving you with one that looks deceptively like a ruined antique but is in fact very special:

While it might look at first glance like a 1930s RCA radio that’s been painted black and had 1970s chair rails stuck on the ends, this is in fact an original by famed industrial designer and RCA contributor John Vassos and is worth thousands. Its style is the sort of thing that could be easily overlooked, too!

In Season 2, Episode 7 of television program “Babylon 5” (1994-1998), you can see a few antique radios in the space station’s Earth History Exhibit.

With the help of some other radio hobbyists, I’ve identified the interesting ones. On the top shelf left to right, the wooden Tombstone radio is an unknown Wilcox-Gay model from around 1934; next is a Zenith 5G500 portable radio with Wave Magnet antenna, the Red square is an Emerson model 560, and finally the blue peaking out of the frame on the right of the top shelf is a 1960s GE radio in the C430A family. None of those are particularly special radios now, although they are nice and interesting, and in the ’90s they were probably easier to find for cheaper.

I recently had the privilege of working on this beautiful 1936 Zenith 5-S-29 tabletop radio. It’s a beautiful 5-tube table radio with a 6-inch speaker and the iconic black Zenith dial and lightning bolt Z pointer. This one is special, too, because it has a swept second hand to enable fine tuning.

This radio came to me locally from its owner who had purchased it on eBay a short time ago in “restored” condition. Unfortunately due to a memory issue with my camera the first set of photos was lost. The radio had definitely had some work, but this is definitely a case of “buyer beware” on eBay: it looked like the previous technician got bored half-way through and left most of the original capacitors intact. About 3 had been replaced with film capacitors, and the electrolytic capacitors had been replaced, but otherwise it was all original. The dial had some coloration wiped off the back, too, and a dried out rubber band instead of a proper dial belt. The zipties were there as well, although they appear to be serving their purpose so I left them alone.

The curved glass dial is held in place by a metal clip ring around the outside. Inside between the dial face itself and the glass was a ring of cork as a spacer.

In order to replace the dial belt it’s necessary to remove the dial ring.

The dials, side by side:

New dial belt slipped over both pulleys, and dial holder replaced:

I carefully re-glued the cork spacer (with its original gap in the ring) to the perimeter of the new dial face.

Dial pointers reinstalled on the dial:

I performed an RF and IF alignment to peak up the signal and really bring out the rich tone. Afterwards, 880 KIXI is coming in nearly spot-on. Prior to the alignment, it was coming in about 910. It tuned very well through all 3 bands – even bringing in 3 shortwave stations on Band C with the shop antenna! It’s that kind of reception that made Zenith famous with their “Long Distance” radios. Even an entry level set like this one was capable of excellent performance.

Reinstalled in the cabinet! Fully serviced and aligned, this radio will play beautifully in its owner’s home with a wonderful rich tone. Just in time for Christmas, too!

If you’re in the Greater Seattle area, I can help with new repairs and routine maintenance for your antique radio. Please contact me!

I recently got to work on something a little bit different – a tube hi-fi stereo console! This particular one, a 1962 Zenith MK2670, was a very high-end unit back in its day. It’s a dual-chassis unit with 19 tubes total, using the 12K25 stereophonic FM tuner and 7K31 stereo amplifier chassis with EL84 outputs. All housed in a beautiful mid-century modern cabinet with built-in stereo speakers featuring 12″ woofers and mid- and high-end compression drivers and horns.

With 19 total tubes, this model features hi-fi integrated speakers with high-efficiency 12″ woofers and mid and tweeter horns, push-pull EL84 output tubes for each channel, and built-in FM Stereo Multiplex decoding for true stereo hi-fi reproduction.

This hi-fi’s owner reported it was working well for several years but started to go downhill shortly before she got in touch to have it fixed. It was taking longer and longer to warm up and sounding more and more distorted, no longer delivering the rich warm sound of a classic hi-fi console. It was good she got in touch – waiting any longer could have led to catastrophic consequences such as component failure or even a fire. I visited her home to test the tubes and pull the chassis, then it was back to my shop for repairs. And what a job it was!

This unit had been serviced a couple of times in its life – there were some ’70s era film capacitors installed, and some of the output tubes had been replaced. Most of the tubes were original Zenith fittings and tested strong, though, so very little needed to be replaced. Since it came into the shop in working condition, too, it made the diagnostic process much easier!

The amplifier circuit is a bit different than most I’ve seen. The negative phase of the output transformers was connected to chassis, and there were two positive phased taps each connected to half of the speakers. It’s an odd arrangement, certainly, which would have let Zenith use woofers of different impedance then the mid/tweeter network without an expensive and complicated impedance matching network. Underneath, though, it’s pretty easy to work on:

Right away there’s some visible damage. This molded ceramic capacitor blew a piece of the ceramic clean off from overheating. It’s unlikely it was doing much of its job at this point. Despite a nice ceramic body and epoxy sealed ends, it’s still an acid-paper/foil capacitor inside subject to failure, and fail it did.

Many of these early disc capacitors were failing as well.

I tested and replaced resistors as necessary, and capacitors. Here’s an in-progress shot showing partial replacement complete. Even the resistors I did remove were very close to spec – Zenith clearly used high quality resistors in this hi-fi. All were shiny with intact bodies and paint, and none had the woody, chalky appearance of a tired carbon resistor.

With the amplifier chassis sorted, it was time to move onto the tuner. It’s nicely shielded on the bottom.

And there’s a lot going on inside.

This radio was build very, very densely and in layers. It’s also a modern hi-fi instrument sensitive to wiring changes, so I had to work without disturbing most of the arrangements. Fortunately, Zenith specified high quality carbon film resistors and they were overwhelmingly within tolerance, so it was just a straightforward capacitor replacement.

Even film capacitors are much different these days. The ’70s 0.47uF 400V capacitor, top, was replaced with a 0.47 uF 630V capacitor about 1/4 the size. Working with a needle-nose pliers in each hand, I was able to thread capacitors into the proper location under component networks without disturbing the top layer.

Now it was time for a power-up test. This particular radio uses an odd multi-tapped output transformer arrangement with drivers hooked up to both taps in the cabinet, so I ended up hooking up 4 distinct speakers for testing.

It fired right up and sounded great! There were a few minor issues to resolve, though. For one, there was a bad volume-invariant hum on the AM band only. This was due to a small short which was corrected. The volume controls were behaving pretty erratically, though, which took some investigation.

The unexpected behavior turned out to be due to a control scheme I hadn’t run into before. The “balance” control isn’t an actual fader; instead, the volume controls for the left and right channel are ganged together with a friction clutch. Turning the outer ring turns both together – but turning the inner ring adjusts the friction clutch allowing one to be turned independently to achieve the left-right effect. At the new set point, then, the outer ring will turn both volume controls together to adjust the loudness equally after the fade is applied. It wasn’t a popular control scheme, being replaced after a couple of years, because many consumers found it to be annoying and counter-intuitive.

After understanding how it worked, however, it turns out that it wasn’t gummed up, it was actually working properly. So, on to the next steps! Adjusting the bias on the channels:

RF and IF Alignment:

Lots of parts came out of this one!

This radio is going to continue to serve faithfully for many years, pumping out a warm and rich hi-fi sound and be a beautiful family heirloom to pass on. They just don’t build them like they used to!

If you need your antique radio repaired, I can help.

I’ve had the opportunity to work on several very nice Zenith radios lately and this one is especially interesting. It’s the Zenith 5-S-220 Cube. This is the first time I’ve seen one of these in person, they’re somewhat uncommon. Electrically, it’s a nice 5-tube radio with a broadcast and shortwave band, and the cabinet is very compact with the speaker firing vertically through the top of the cabinet. The black dial in the face is very easy to fine-tune.

It was sold as in running condition, and it worked okay on the standard broadcast setting, but with the switch on the Treble Cut tone setting the set picked up bad warbling low-frequency interference, called motor-boating. It also just didn’t sound that good, and Zenith radios are known for their excellent tone even from their small radios.

The chassis is supported on small risers to replace compressed paper spacers. It’s fairly cramped in there,but the chassis slides out easily when the spacers are pulled out and the speaker socket makes service easy.

Underneath, the solder joints were all very good in fact. Mostly original resistors retained.I tested the resistors and many were well outside of their specifications; there were several other problems as well.

The previous service had replaced all but one of the original vintage tubular capacitors that are candidates for replacement in any vintage radio.

The resistors were all original. This frequently isn’t a problem – vintage resistors can still test within tolerance, and if so, don’t need to be replaced – but these were almost all bad. I found some which measured as much as 250% of their marked values. The radio actually played like this, it just goes to show you how robust these tube circuits were. They’d tolerate a lot of abuse and still sound passable.

I replaced the vintage capacitor and many resistors but the motor-boating persisted. Throughout all of this, the volume is lower than I’d expect, too. I went about replacing the Micamold capacitors which can frequently go leaky and exhibit odd symptoms. These are in fact paper capacitors in a molded package – not true mica capacitors which tend to hold up well even today.

While poking around at those connections, an entire solder blob moved – the ground connection had broken off entirely:

I replaced this one with a true mica capacitor and a solid ground connection. A few tweaks to the alignment later, the motor boating was gone, but the low volume persisted. Even on the normal position it was still lower than it should have been. I examined the tube line-up versus the schematic. This radio had a 6V6GT tube installed when the radio was designed for a 6F6G tube.

In general, those tubes are “fairly” close and you can often plug them into each other’s sockets. The radio will play, but with more distortion and lower volume, as they do have distinct design characteristics. The mismatch will get you significantly lower volume as a result, too. I had a 6F6G which tested like new in stock and made the exchange:

With this, the radio roared to life with perfect volume. It sounds absolutely fantastic, especially for such a small cabinet and speaker. It also goes to show: be cautious buying radios on eBay. They might even work, but often may have hidden problems like this. It’s worth it to ask for under-chassis photos to check the amount of work that was done.

With the feedback problem corrected, I performed a precision alignment and the dial tracks in perfectly.

Overall, to bring this radio up to standard I replaced many resistors, replaced several capacitors with modern technologies, repaired a broken ground connection for the capacitors, aligned the radio using a standard signal generator,  and replaced a wrong tube. Now it looks as good as it sounds – practically brand new.

Antique and vintage radio inspections and repairs.

Other radios

A local client just brought in a very interesting Zenith tabletop radio from just after WW2, the 1946 Zenith 6-D-029 Consoltone mantle radio. This is one of the iconic “boomerang” dials Zenith produced for a couple of years after the war. A variety of sets were made with similar styling; in this case the 6-D-029 is a 6-tube AC/DC radio with a combination of octals and loctal tubes.

This radio was repaired in the ’90s by a radio shop in Portland, OR but came to me in non-working condition. That’s not unreasonable for a radio to need another round of service after 20 years, and it looks like they did good work last time.

Checking out the tubes, other than one which was conveniently labeled (and testing confirmed) “weak”, they all had good filaments and good emissions. Something else was clearly the problem. Given the set’s owners don’t own a tube tester, the tube labeled “weak” must have been from the last time the radio was serviced; this one was the RF amplifier front-end tube.

It’s been pretty well cared for – the cabinet is in solid shape and there’s only a tiny amount of dust inside. Underneath, however…

There are several things going on here. Number one is somewhat obvious: something has released some smoke inside. In addition to that, the electrolytics used in this repair were different ages. There’s the blue CDE dual-section capacitor, and a Jamicon 33uF 450V capacitor hooked up as the second filter. Time to start pulling parts.

That Jamicon capacitor is visibly bulging from one side, and testing confirms it’s definitely dead. Of the CDE dual cap, one section was badly out of spec, and the other section tested open as well.

One of the ceramic disc capacitors blew itself apart – rather violently damaging a mylar capacitor near-by and generally making a mess of things. I replaced all of the same model of capacitor with new 630V film capacitors just to be safe.

After replacing the components it was time for the first power-up. No smoke! But, no sound either. Checking around on the voltages, something wasn’t quite right. B+ on the output tube was about 50% high, and there was no voltage on the screens of any tube.

Careful inspection and wire tracing got to the root of the problem: the wire between two tie points, supplying high voltage to the screens of the output tubes and the plate and screens of the RF and IF tubes, had broken at some point – likely from 68 years of metal fatigue. This was likely the root cause of the original failure: the ceramic disc capacitors were rated at 100V. With 4/6 tubes not conducting, the power supply was delivering over 160V when the nominal operating B+ was about 100V under load. This is well over the rating of those ceramic capacitors and could have caused the violent failure which took the radio out of service.

That’s more like it! A jumper confirms the issues has been located. The new capacitors are rated 630V, so should have no trouble with voltage spikes.

I soldered a 2″ segment of wire to make the connection permanently.

With that repair made, the radio fired up loud and clear!

Time to adjust the alignment a bit:

Then finally, back into the cabinet and ready to go home.

With all new film and electrolytic capacitors, and a replacement tube, this Zenith table radio is going to last a very long time before it needs to be serviced again and sound great the whole time.

If you need your antique radio repaired, Rain City Audio can help.

I just finished a new project over at Rain City Audio – 1938 Zenith 7-S-363 Repair

This Zenith radio was brought in by its second owner after original parts catastrophically failed. It took a while, but after an extensive electrical overhaul and locating some replacement parts, it looks and sounds fantastic and will play beautiful music for many years to come. “Zenith, the quality goes in, before the name goes on.”

Check it out at http://www.raincityaudio.us/blog/1938-zenith-7-s-363-repair!

This 1936 Zenith 5-S-29 was in the shop for a complete overhaul with all new resistors and capacitors, a new dial lamp socket, tube testing and alignment. After all that service, it looks and sounds fantastic and is going to last for a long time to come in a local collection.

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Check it out at Rain City Audio

This radio repair is cross-posted from Rain City Audio

This classic 1959 Zenith C845M radio came into the shop for a full repair after sitting unused for some time. It has the classic late ’50s styling, and a dual speaker high-fidelity design.

It’s an 8-tube radio with a 35C5 output tube good for maybe 3W of maximum output, but it has great sound quality.

Inside, it’s covered in a lot of original dust, and is missing about half of its tubes:

Here’s a good shot of the two speakers, with a single capacitor high-pass filter on the tweeter.

Underneath it’s mostly original although saw some service at one point. Very unfortunately, it’s a series-string radio; otherwise it’s quality construction. There was plenty of room under the chassis to work,  too. Zenith used precision resistors in this build and they were all within tolerance. After the film capacitors, the electrolytic capacitors were replaced.

Component replacement complete:

Time for a first power-up!

And immediately, one of the tubes that had tested earlier immediately blew its filament. So, it was time to replace that tube and for good measure the other two as well, so it received a fully new tube compliment.

Finally, time for an alignment. Using the alignment tool, I adjusted the cores inside the IF transformers. This cleaned up some of the remaining distortion and increased the volume a bit.

The components have drifted a bit so the dial tracking isn’t perfect, but it’s close. Looking carefully, one of the IF transformer has a manufacturing error – the label stamped into the top of the can has an inverted “F” when a technician set the stamp incorrectly.

Back in the cabinet!

I took a video of it tuning through the range on both bands:

This is going to sound great for a long time to come. It does have a phono input on the back where you could connect an external input, but, due to the series string construction it’s not safe to connect anything modern to that input as it’s a shock hazard.

This does justice to the High Fidelity label, it sounds great with the large speaker and dedicated tweeter, and it plays loud and strong on both AM and FM. On AFC, tuning between stations is very crisp. This should be a great daily driver!

Rain City Audio Vintage Radio Repair

More Rain City Audio Projects

Original Article at Rain City Audio

This 1958 Zenith Hi-Fi came into my shop for a full overhaul including an electrical repair, dial re-stringing, and some work on the turntable. These vintage hi-fi consoles are some of the best sounding pieces of vintage gear around, and this one’s no exception with a pair of 12″ woofers and a pair of electrostatic tweeters. Read more for details!

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Check it out at Rain City Audio

From the Rain City Audio Repair Blog:

This very nice Zenith 5-S-126 came through the shop a little while ago. It was originally purchased by a local collector from eBay already restored and playing, and served well for a couple of years, until it started having some trouble.

The 5-S-126 is a 1937 Zenith radio, with 5 tubes and a 6″ speaker firing up through the top of the cabinet. It receives the AM broadcast band and two shortwave bands. The owner reported that it used to have great reception, but it had slowly picked up a bit of hum, as the reception faded to nothing.

The previous technician did a workable, if not especially pretty, repair job. I cleaned up some of the wiring, moving the two filter capacitors to more secure tie points and replacing them with brand new units for long life and reliability; the installed ones were starting to wear out. The radio then received an IF alignment which was pretty significantly off, but there was still no over-the-air reception.

That would be why! The 6A8 converter tube was dead, showing no emissions at all. Replacing it with a new old stock 6A8G tube brought the radio to life right away with great sensitivity and tone. Then it was back in the case and back home!