Philco 20

 


Home Up Antenna Rotating Antenna Philco 20 Model 45 90 37-61 Philco 39-30 40-150 40-150 #2 40-150 #3 40-180 40-190 41-221 41-290 42-350 46-421 48-1256 Service Bulletins

 

 

 

 

IM000001.JPG (143296 bytes)

This Philco 20 must have manage to irritate the owners dog one day.  So it took a chunk out of the grill lattice work.

IM000093.JPG (77064 bytes)

The flash brought out the wrinkle in the grill cloth and illuminated the backing board.  these are not visible with out a flash.

IM000094.JPG (71873 bytes)

There are multiple layers of  lacquer  and hand rubbed paste wax.  

IM000095.JPG (74997 bytes)

Nice interior shot.  Don't worry.  My repair sticker is on a magnetic sticky card.

Before

After

Philco Model 20 (1934 vintage) is a TRF (not superhetrodyne) radio.  It has all tuned circuits to receive and detect the audio from the air.  Here are some pictures of the restoration. 

Electronic Restoration

The only restoration challenge is restuffling the large multi section capacitor.  There in which the real challenge is minimizing the melted tar or pitch.  I held the capacitor in front of a LP space heater and kept it moving.  Softening of a layer that contacts the inside of the can is the goal.

I removed this capacitor from the chassis.  I was later told this is unnecessary.  You only have to unbolt the retaining screws and pull up on the can while gently restraining the bottom cover.  It separates.  The bottom is not affixed to the upper can.  Then clip the wires, clean out the can and add new capacitors. 

 The smallest electrolytic that I had on hand was 10 uf.  They work fine.  10 uf is well with in the capacitor specifications of the #80 rectifier tube (I always check).  I used a Polypropylene 0.1 uf 630 volt as well for a direct value replacement of .13 uf across the choke.  Riders Vol 2 page 2-3,4 Vol 1-6 from Nostalgiair.org

 

IM000002.JPG (137570 bytes)

IM000003.JPG (135785 bytes)

IM000005.JPG (268979 bytes)

 

This radio seems to have been stored near a coal shed.  Typical seventy years of dirt.

IM000008.JPG (249775 bytes)

IM000007.JPG (348111 bytes)

IM000004.JPG (255674 bytes) Bottom view of multi section can capacitor.

 

IM000016 crop.JPG (7206 bytes)  A fully restored, operational chassis!

 

Resistors

I found all but two resistors out of tolerance.  Most beyond 100%.  I replaced the resistors with two 1/2 watt in parallel to obtain 1 watt dissipation.  Of course the individual resistors wattage are double the needed value.  I have saved the original resistors in the event that someone would later intend to make reproduction "dog bone" resistors to maintain the vintage look. 

 And how about those Dog gone Dog Bone Resistors?  Try Syl's web site.  

Bakelite Capacitors

After removal, clip the lead wires exiting the rivets, heat with a 40 watt focused spot light, and push the insides out with a small stick through a rivet.  I have broken a case before, by using a screw driver.

Clean with contact cleaner and solder in new caps.  Season to taste and Replace.  Check your schematic or see, http://www.philcorepairbench.com/partinfo.htm and select the Bakelite Blocks for what is inside.  Thanks to the Philco Repair Bench  for maintaining such a valuable Resource!

Alignment

Alignment is simply putting the RF generator on 1400 khz, setting the dial on 140 (1400 khz), placing a loop of wire near the antenna (a length of wire) and adjusting the three compensating capacitors mounted on the variable air capacitor.  Some models only have one or two.  

If tracking is off, bending of the outer most disc of the air capacitor is needed.  This radio tracks accurately.  No adjusting is needed.  However, several, not all, bent plate sections were apparent on the center section rotor.

 

Cabinet

IM000017.JPG (285088 bytes)   IM000018.JPG (294058 bytes)   Before stripping.  This is the condition as originally found.  Normally I try to save the original finish.  But as you see there was little to salvage.  This radio was destined for the dumpster.

IM000072 crop.JPG (33653 bytes)New arch added.  Veneer, removed from under a trim strip did not match.  A new piece of wood backed veneer was used in the final repair. It was quite hard to color match this new veneer.

 

IM000072.JPG (220769 bytes)   IM000073.JPG (267770 bytes)  After stripping.  

If you look close the toned wood filler can be seen.  It is not as red in sunlight and interior lights.  The camera's flash seems to bring out the Red tone of the filler.

Finished radio.  The tinted wood filler takes the color matching markers well.  Better than stain.IM000094.JPG (71873 bytes)

The Tan knob felts have been changed to Dark Brown.  They no longer contrast with the finish.

Hit Counter

 

 Contact me including your thoughts and comments. 

Please see the LINKS page.  I have collected many resources over the years.

135,912 unique web site visitors (14,499,000 hits) from October 2004 through August 2011.

Copyright 2004 - 2012. All rights reserved.