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Radio Restore

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May 15,2010: It all started when it was time to clean out the barn. Sitting there, was this forlorn tube radio. Always the electronics junkie, I decided to migrate from old PCs to see if I could make this thing work again.

First things first, it was off to google for some background info. The most important thing is NEVER to power on the radio without first checking and replacing the capacitors and out-of-tolerance resistors. Failure to do this will probably let out the magic smoke and leave your wallet considerably lighter. While tubes are tough, too much voltage in the wrong place is deadly for them.
<Shameless plug> Thanks to the members of the AudioKarma and VideoKarma forums for their help and putting up with my relentless questions! </Shameless plug>

As you can see, the radio is a Fleetwood "Stereo Hi-Fi", made in the early 1960s. Fleetwood is not a widely-known brand outside of Canada; they were located in Montreal, Quebec. This particular set features a stereo turntable and AM-receiver. This was a cost-cutting measure, since FM did not take off in Canada until later.
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Finding background information proved to be difficult. While the back plate (left) has a model number (4068), there is absolutely no information to be found! A second paper label actually indicates the chassis No. and a model number of 2053. VideoKarma member electroking was able to find the schematics and tube layout diagram. The same diagram can be seen stapled to the inside of the cabinet in the next photo. There are, however, some differences with the schematic, leading me to wonder if the 4068 is a revised version of the 2053 chassis.
Here you can see one of the two 8-Ohm speakers built in to the cabinet. Fortunately, the mice did not damage them, but they did get everywhere else. The buggers gnawed through the dial string though, which means more work for me. (You can see it on top of the cabinet in the first picture above)
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May 16,2010:I decided to start with the easiest part; the turntable. There aren't many electronic components, only a motor and power switch- the rest is all wechanical. As you can see, it is in a sorry state. The tone arm hinge is broken, and it's just covered in dust. (I've removed the on/off switch for cleaning.) There's a lot of brown paint everywhere too; the last person to paint the cabinet wasn't too careful! The turntable itself is from England, a B.S.R. UA-14 with auto-changer. The deck will play 16, 33, 45, and 78 RPM records.
Nearly fifty years of dust... The switch knob has been cleaned, but the label plate has not. The parts all restore to a clean ivory white. The main problem with the mechanics is the gummed-up grease. This means a lot of cleaning and de-greasing to get everything running smoothly again.
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Here's a shot of the bottom of the deck; there's plenty of dried gunk to clean... lots of lithium grease and electric motor oil later, we're back in business. There were some issues with the automatic shut-off catch, but some lube and a spring adjustment later, all seems to be working.
May 17,2010:The cartridge itself is a Ful-Fi TC8S type, and crystal to boot. There are two styli in a turnover configuration. The TC8RS is for 78s, and the TC8G for LPs with smaller grooves. The problem with crystal cartridges is that the Rochelle salt crystal is hygroscopic; unless well-sealed, they absorb water from the air and deteriorate. The set was stored in a fairly dry location, so I'm hoping it may be OK... If not, the best option is to replace it with a ceramic model- these are more rugged and are usually drop-in; both ceramic and crystal pick-ups do not need a preamplifier.
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May 22,2010:I said that the tone-arm hinge was broken. The crack was not in a high-stress area, so I've pached it with epoxy and some pieces of scrap metal for extra support. Here's to hoping it holds...
The crystal cartridge was completely dead. While out and about, I managed to score a ceramic cartridge for the set. It's a Philips GP-815 (stereo). There's even a mounting hole in the top, making it a drop-in replacement!
Sorry for the picture quality- the distance is too small for normal zoom, but too far for super macro mode.
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June 19,2010:Now I had to balance the tone arm and set the tracking weight. This is a crude balance made out of LEGO and a very smooth metal rod. The coin is exactly 6 grams. The more observant will note a three week jump in time; I was taking some family time to visit relatives.
The tracking weight seems fine, since the needle sits firmly in the groove. Here it is playing a test an awful record (my tastes, at least) that I would't mind losing.
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The control knobs were really dusty. A quick polish and they look great again. Fortunately, wood paint doesn't adhere to plastic or metal!
June 20,2010:On to the chassis... There's a lot of work to be done here. You can see the power transformer and tubes, as well as the tuning capacitor. The tube lineup consists of a 6BE6, 6DC8, 6CA4, and two each of 6AU6 and 6AQ5 for a grand total of seven. All the filaments check OK with a DMM, and they still hold a vacuum, since the silvery ("getter") coating is still shiny. The tubes are a bit dusty and can do with a gentle cleaning.
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The chassis is fairly clean, and everything seems to be in good shape. You can see a few rust spots, which I've been treating to a good dose of rust-remover. There are some before and after shots below. Plenty of elbow-grease required, but it's well worth it.
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Restringing the dial was a challenge... There are many ways they can be strung, and I had no reference to go by. Fortunately, a common two turns around the tuning pulley, and one on the tuning knob axle left me with a taut cord. While there's no substitute for real tuning cord, some people have had success with braided fishing line. The two key points are the diameter and "grippiness" of the cord. Here, I've used cotton thread with a little candle wax on it. You need just enough to make the thread grip, but too much will make it slippery. Rosin might also work, but I don't have any on hand. The other issue is durability; the thread feels sturdy, but it is not as heavy-duty as the original. We'll see how it holds out.
While de-rusting, I found that the coil in the reciever's LC circuit was in bad shape... I will need to re-build it, since a replacement would mean having to re-align the set via the IF tuning slugs.
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June 22,2010:Sourcing replacement wire isn't easy... Fortunately, I had some CRT yokes in my parts box with the right kind of wire.
Here's a snapshot of the coil while it is being wound. I've tried to match the original winding pattern as closely as possible- the original coil was so damaged that it wasn't possible to count the number of turns, only the total length of wire used. The logic is that the same total length of wire wound in the same pattern will give the same number of turns.
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Here's the rewound and re-waxed coil back in place.
June 29,2010:After removing all of the rust from the transformer, I gave it a new coat of paint. All I had was red metal paint, but it is coincidentally the same color as the dial pointer. You can also see the filter capacitor that has been removed and gutted in preparation for re-stuffing. I nearly lost a tube removing the capacitor- the bloody thing wouldn't come out, but when I tipped the chassis to see what was stuck, it came loose and hit the rectifier. After some colourful language and a close look at the tube (looks OK, not cracked),I immediately removed the tubes and put them in a safe place to prevent a catastrophy.
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The original loop antenna was mounted on a crappy piece of cardboard. I made a better wood frame and fixed the antenna to it.
June 29,2010 (well, actually, June 25, but I took the photo on June 29):Once again VideoKarma member Electroking came through- He pulled together a complete set of tubes for the console and made me an offer I couldn't refuse... Two days later I had a full set of spares. If he keeps this up, I'll need to get a plaque for the set that says "This restoration made possible by Electroking" :-)
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July 6,2010:My replacement capacitors arrived! I bought these from the folks at JustRadios- it's nigh impossible to get the exact same types at any place other than a specialty dealer. Even they didn't have the 6 μF electrolytic ones I needed, but there were more than enough others to choose from, so I just ordered 1 and 5 μF models, and installed them in parallel. The big filter capacitors are the most expensive part of the order. They came in at about $5 each(!!)
Here's a snap of the bottom of the chassis after replacing all of the smaller capacitors. Some of them were completely buried, and I had no choice but to clip the leads and attach the new to the old. The same held true for leads soldered directly to the chassis; the metal frame requires a lot of heat to solder to, so it was much faster (and easier on the soldering iron) to clip and solder to an existing lead, which will heat up faster. You can also see the piggybacked electrolytics and the new line filter caps.
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I ran in to some problems installing the new filter capacitors. They were just too big to fit in to the original can, as I had hoped. I chose to install them under the chassis, and put the original filter capacitor (now empty) back in place just for looks. The more observant among you may notice that there are now two ground wires coming from the negative terminals of the capacitors. I had to re-route several ground wires that were soldered to the ground lug of the filter can. The other ground wire runs off to the top-left corner of the chassis, and serves more to hold the "three-pack" of 40 μF capacitors in place than anything else.
While waiting for the capacitors, I also rigged up a simple switch so that I could also use the phono inputs for an external source (such as a CD player or reel to reel deck). It's nothing more than a dual-pole dual-throw push button, and some RCA jacks and plugs. I plan to mount it on the back of the cabinet to fill a hole in the particleboard backing where the mice chewed at it.
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July 12,2010:Now the time has come for preliminary testing... I borrowed a variac from work to help ease the set back to life- first tests are just checking the power transformer and the tube filaments. Here, you can see that the set is at about 1/2 of the normal operating voltage; the target filament voltage is 6.3v. Despite the light, you can see the dial lights are lit up.
A shot of one of the 6AQ5 tubes warming up, at about 1/2 the normal filament voltage. The light in the background is from a dial light.
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Here's the same tube at full operating voltage... it looks rearing to go! Tomorrow's another day, and that's when we put in the rectifier and fire up the set for the first time!
July 19-26,2010: Not much photogenic going on, really. I've been working on adjusting the set's AM circuit. After some adjustments and a re-connected coil, I was able to receive some AM stations. Hacking a 50' piece of CAT5 to the antenna termnial via an RJ-45 jack pulled in a much cleaner signal. At this point, I had to adjust the trimmer screws on the tuning capacitor, and found that there's an error in the layout diagram linked earlier; C1 and C2 are mislabeled. The first step was to fix the station position on the dial, followed by the signal clarity. The picture is a 10 second exposure of the two 6AQ5 tubes while tuned to a station; there's some healthy blue flourescence!
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A 15 second exposure this time. All of the electrical work on the set is now complete; the next step is refinishing the cabinet.
A fair amount of time with scrapers and a paint stripper (heat gun) is in my future. Here's the cabinet in an intermediate stage as I'm working on removing the old paint. The brown is not original; the original was a light yellow/tan coloured "paint-on" veneer where the wood grain is faked by the brush strokes. We're going right down to bare maple and varnishing it. (No, we're not defying gravity, just a change to portrait mode... but it looks funky - wall-mounted console, anyone? - so I left it)
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Uncovered this while scraping off paint; it appears to be a lot number tag or so; anyone know what "2 E13" might mean?
The entire cabinet stripped of paint and ready to varnish. The lid has been removed in order to make access easier.
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The varnished cabinet. Note that the hardboard sections have been left bare because they will be covered with veneer.
August 10,2010: All done! Finished veneering and varnishing the cabinet.
The first two pictures are sans lid because it was still drying. Gallery below:
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