Rebuilding a Philco Tropic 42-730EZ - Printable Version
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RE: Rebuilding a Philco Tropic 42-730EZ - Arran - 10-17-2014
I think that the last time I needed some rubber mounting strips for a dial glass I cut up an old bicycle inner tube, rubber bands have a habit of drying up and rotting around here. In any even it looks like the metal backing plate needs to be taken out, derusted and painted, (or is it rusty brown flocking?) but that is a cosmetic job that Ron can handle later.
Regards
Arran
RE: Rebuilding a Philco Tropic 42-730EZ - Ron Ramirez - 10-18-2014
I t ' s A l i v e . . .
[Image: http://www.philcoradio.com/images/phorum/42-730EZ/Image00013.jpg]
This afternoon, I hooked up the speaker connector, tested all seven tubes (only had to replace one - a 7C6), connected my temporary in-basement antenna, and fired it up.
It sounds good, and is receiving signals on all but one of its five bands. Band 4, the 25-31 meter band (9.3 to 12 mc) is dead - no sound, nothing.
But it is nice to hear my SSTRAN playing music through the 42-730.
RE: Rebuilding a Philco Tropic 42-730EZ - NostalgiaRadioTime - 10-18-2014
That feeling you get when you first power up a radio after an electronic restoration never gets old and never varies. There's always that nervous anticipation followed by excitement and a sigh of relief when it finally comes to life receiving stations! Congratulations on another job well done, Ron!
RE: Rebuilding a Philco Tropic 42-730EZ - Ron Ramirez - 10-18-2014
NostalgiaRadioTime Wrote:That feeling you get when you first power up a radio after an electronic restoration never gets old and never varies. There's always that nervous anticipation followed by excitement and a sigh of relief when it finally comes to life receiving stations!
Absolutely right, Greg. And thank you!
Epilog:
The 42-730EZ is aligned and plays very well on all bands save for Band 4, "25-31 Meters" (9.3 to 12 mc, the second band from the top on the scale). I will deal with that later. Since the same coils that are in use on Band 4 are also used with Band 5, I do not believe it is a coil issue. Looking at the schematic, there is a mica cap - (27), 375 pF, that is switched in with the oscillator coil (25) on Band 4. On Band 5, a different cap, (26), 80 pF, is connected to this coil instead.
Oscillator coil (25) is also the oscillator coil for Band 3. And Bands 3 and 5 work. A preliminary look at the schematic seems to point to cap (27) as the possible culprit, although it could also be trimmer (19D) but I would suspect the mica cap (27) before the trimmer.
I hesitate to dig into mica caps such as (27) because it is sort of buried between oscillator coils under the chassis, which is the main reason why I'm stopping work on it for now.
Anyway, here's a shot of the radio, reassembled and playing merrily away:
[Image: http://www.philcoradio.com/images/phorum/42-730EZ/Image00014.jpg]
This table model radio has surprisingly good tone and sounds great.
I think that's all for now on this one, folks. Next case.
RE: Rebuilding a Philco Tropic 42-730EZ - Ron Ramirez - 10-18-2014
(10-17-2014, 11:45 PM)Arran Wrote: In any even it looks like the metal backing plate needs to be taken out, derusted and painted, (or is it rusty brown flocking?)
Forgot to mention: Yes, Arran, that is flocking that has a rusty brown color. I carefully cleaned the glass before reinstalling everything in the cabinet; the photo just above shows the clean glass and you can see the dark brown color of the flocking on the backing plate.
RE: Rebuilding a Philco Tropic 42-730EZ - sam - 10-19-2014
ron great work
now put on ebay say that Remirez guy recapped for big bucks
RE: Rebuilding a Philco Tropic 42-730EZ - Arran - 10-19-2014
If that 375 mmf mica capacitor C27, is really the problem, and it is buried, it may be easiest to remove the band switch assembly to get at it rather then trying to get a soldering iron between the coils. If this is the case then it would be best to drill out the rivets holding the trimmer capacitor bank in place, and desolder the end grounded to the chassis, rather then to remove each wire going to the band switch assembly, then you can use some small machine screws, nuts and washers to reattach. Trimmer 19D should be easy enough to test on it's own by disconnecting one end, it's possible that it may be the culprit if some garbage like solder or a strand of steel wool got into it, leakage is not very likely since it uses a mica sheet.
Regards
Arran
RE: Rebuilding a Philco Tropic 42-730EZ - varrojames - 10-20-2014
very nice job
RE: Rebuilding a Philco Tropic 42-730EZ - Ron Ramirez - 12-11-2014
Revisiting this topic to add a little new info.
Today I decided to pull the chassis again and remove that 375 pF cap (27). As it turns out, it wasn't buried too badly and I was able to remove the original with little difficulty. It appears that 375 pF is no longer a standard value, so I paralleled a 270 pF and a 100 pF to get 370 pF, and installed that in place of the original.
Result: Band 4, "31-25 M" is now working, but refuses to align properly - the oscillator trimmer for this band will only allow me to raise the 12 mc test frequency as high as 10.6 on the dial before tightening completely. As you folks may recall, I have a Canadian 51A which is very similar to this 42-730EZ, and which has the same problem.
Any suggestions? Should I try changing that homemade 370 pF cap with a 350 pF (250 pF and 100 pF in parallel)? We can't go too low, else the frequency will be way off in the opposite direction. Band 5 has an 80 pF cap in series with the oscillator coil instead of a 375 pF cap; and both bands use the same coil.
RE: Rebuilding a Philco Tropic 42-730EZ - mikethedruid - 12-12-2014
You might want to try a 330 pf and a 47 pf in parallel, since the original was 375pf, more than the 370 pf you made, if the 350 pair you make doesn't work. Looking at the schematic it seems that might be the way to go. Good luck.
RE: Rebuilding a Philco Tropic 42-730EZ - Joeztech - 12-18-2014
Ron;
I had a similar experience with the IF transformers in my Philco 40-201. Those spring loaded nuts that hold the transformer inside the cans are a real bear to remove without damaging the can. The can metal is so thin that it is easy to cut or slice with tools or the spring loaded nut when removing and installing. The wires in my set were quite brittle and the insulation was crumbling away. That fact plus the general condition of the top surface of the chassis was one reason I removed the IF transformers for wire replacement and all parts from the top of the chassis for cleaning and then priming and repainting of the chassis with the brushed nickel paint you recommended.
Great job you have going there!
Joe
RE: Rebuilding a Philco Tropic 42-730EZ - Ron Ramirez - 12-21-2014
(12-12-2014, 01:16 AM)mikethedruid Wrote: You might want to try a 330 pf and a 47 pf in parallel, since the original was 375pf, more than the 370 pf you made, if the 350 pair you make doesn't work.
I don't have a lot of values in mica caps, so today I went back inside the set and replaced the homemade 370 pF cap with a single 270 pF cap. No change. (well, 12 mc did go up maybe 100 kc.) So I replaced the 270 pF with a 390 pF and called it a day. I'm not going to mess with it any further.
I added the same type of LED lamps with flexible leads as I installed in a couple other Philcos, and the dial really looks great now. Sorry, no picture. Maybe some other time.