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Old 05-14-2018, 11:24 PM
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Zsuttle Zsuttle is offline
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Philco Model 70 Restoration w/Pictures

I was lucky to pick up this Philco Model 70 off of craigslist for a reasonable price from a family that had owned it since new.
70frontoriginal.jpg
First photos of the chassis indicated that it was well loved by the family, having been recapped in the 1950s or 60s.
70chassisundersideoriginal.jpg
I began removing the caps, which luckily had been placed on the original Bakelite blocks.
Rebuilding was fairly straightforward, though the blocks do break easily if pressure is applied to the sides when trying to remove the old caps.
Note for anyone rebuilding, one of the capacitors has a resistor inside
70undersiderecapped.jpg
I then made notes that the 80 rectifier and the 47 audio output tubes were bad and replaced them.

It seems most of the 70's suffer from an open coil or two, citing the early plastics as the culprit. Tons of people had previously published data on what gauge wire to wind with, making it relatively simple. I used 32 Gauge enameled magnet wire with 69 turns for the primary and using a piece of plastic to wrap the new wire around. Boy is hand rewinding fun!
70NewCoil.jpg

After I cautiously powered on the set, and used a short 6ft wire for the antenna. I was able to pick up stations with relative ease, though the volume pot needed to be cleaned.

Proceeding to the worst part, Someone had dumped lacquer all over the cabinet and let it run, It looked good from a distance, but it sure looked ugly.
I began stripping the finish off, not something I wanted to do, but the cabinet needed it.
70firstsand.jpg
Notably, the front panel had warped away from the cabinet causing all of the pillars to crack.

The right center pillar was completely missing the wood, with only the backing remaining. After a few test trials, I fabricated a piece of mahogany to match the arch and glued it in place. Someone had stained the backing so It would look OK from a distance, which can be seen in the first photo.

After a final cleaning, I began sanding the cabinet to begin for lacquer spraying. Although it was difficult to tell exactly how the original Philco Cabinet looked, I elected to go with some of the popular designs I had seen, though not original.

The final product came out after 3 coats of lacquer, a little bit of light sanding and a 4th final coat. I hand painted the darker edges around the radio and the base.
70finished.jpg

I had to rebuild the cutout for the speaker panel after mine disintegrated, using two picture frame mats glued to each other, tracing the pattern onto it. It's a pain to cut out, but well worth the effort.

I've yet to reinstall the chassis, namely for letting the paint dry, but I was too excited to finally put the speaker and new cloth in to wait till later.

This was definitely a fun project, though with the radio lacking the Automatic Gain Control, it can be quite annoying to tune, with the local stations overwhelming the more distant ones. Overall, a great project and another radio I hope someone can enjoy for many years to come.

~Zach
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Old 05-15-2018, 12:03 AM
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Electronic M Electronic M is offline
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Those replacement caps look more like late 30's to mid 50's. Even by the early 50's repair shops were starting to favor the plastic shell types over the paper cased caps, by the 60's orange drops were becoming the repair shop favorite.

Those coils tend to go open from corrosion of the windings I don't think the material in the forms had anything to do with it. The 60 chassis and the 80 both tend to have open Ant. and or Osc. coils.
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Old 05-15-2018, 06:19 AM
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Zsuttle Zsuttle is offline
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Quote:
Originally Posted by Electronic M View Post
Those coils tend to go open from corrosion of the windings I don't think the material in the forms had anything to do with it. The 60 chassis and the 80 both tend to have open Ant. and or Osc. coils.
I had tended to hear that the secondary winding was made from enameled copper wire whereas the primary was cloth coated. A few sources stated that the celluloid plastic was the culprit for dissolving the primary but not secondary windings. But yes, corrosion of any sort was the cause of the open coil(s)
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Old 05-15-2018, 11:26 AM
Titan1a Titan1a is offline
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It looks nice so far. I look forward to seeing the finished radio.
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Old 05-15-2018, 04:11 PM
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Well, I'm extremely happy to report that the radio is now back in the cabinet and fully functional. I'm still waiting on a proper knob for the power switch, but I used one off a similar Philco model 77. The chassis was so rust covered that I've elected to not to clean too much of it, maybe I will one day.

20180515_162833.jpg
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Old 05-15-2018, 07:45 PM
WISCOJIM WISCOJIM is offline
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That is the proper knob for the power switch, depending on when your Philco was built.

https://groups.google.com/forum/?hl=...no/Iz3Lqr9qv5o

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Old 05-16-2018, 10:53 AM
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decojoe67 decojoe67 is offline
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Very nice work and it's great to have another one of these classics saved. I have a 70 too and enjoy playing it very much. It may not be as impressive as the 90, but with it's straighter, more simple lines, it's a beauty on it's own. I had researched the proper knob set and in period literature you will find both the small rosette tuning/three small plain knobs, and the large rosette tuning/2 small rosettes/one small on/off knobs (like the 90). I also chose the latter.
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