Rebuilding a Philco Tropic 42-730EZ
Posts: 4,639
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
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
(This post was last modified: 10-17-2014, 10:45 PM by Arran.)
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
I t ' s A l i v e . . .
[Image: http://www.philcoradio.com/images/phorum...e00013.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.
--
Ron Ramirez
Ferdinand IN
Posts: 1,521
Threads: 240
Joined: Sep 2012
City: West Bend, Wisconsin
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!
Greg V.
West Bend, WI
Member WARCI.org
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
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...e00014.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.
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
(10-17-2014, 10:45 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.
--
Ron Ramirez
Ferdinand IN
Posts: 2,570
Threads: 336
Joined: Jun 2013
City: lawrenceville nj
ron great work
now put on ebay say that Remirez guy recapped for big bucks
Posts: 4,639
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
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
Posts: 10
Threads: 8
Joined: Oct 2014
City: CA
very nice job
The thankful receiver bears a plentiful harvest.
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
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.
--
Ron Ramirez
Ferdinand IN
Posts: 1,824
Threads: 114
Joined: Jul 2014
City: Sneedville, TN
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.
Posts: 348
Threads: 48
Joined: Oct 2013
City: Tioga, Texas, USA
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
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
(12-12-2014, 12:16 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.
--
Ron Ramirez
Ferdinand IN
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
bridkarl
|
I have two PT-6 chassis. On both there is a blue wire that runs from the above chassis transformer to pin 6 of 7C6. So t...bridkarl — 07:23 PM |
Cannot Adjust an IF Transformer’s cores
|
Joseph, now you are an engineer!!RodB — 06:37 PM |
PT-6 antenna connections
|
Hi, reading your explanation I can see the confusion. If you take it one connection at a time it should result in a desi...RodB — 06:34 PM |
Cannot Adjust an IF Transformer’s cores
|
It works! I received the PCBs this morning in the mail, and put everything together. I reused the base from the original...jrblasde — 04:32 PM |
PT-6 antenna connections
|
I seem to have lost my way on this PT-6.
I see the antenna aerial transformer schematic - I’m reading pins 1 through ...bridkarl — 12:30 PM |
40-150 General questions
|
Good thing you're a good electrician ... the pictures show a lot of rewiring in your future! Take care and BE HEALTHY!...GarySP — 11:52 AM |
40-150 General questions
|
I think RobB has it right. It is a part number and looks like its stamped on the chassis and that wasn't something you ...klondike98 — 11:41 AM |
40-150 General questions
|
It's most likely a part number. Most of Philco part numbers are in that format. I looked at the parts list for this mode...RodB — 08:10 AM |
40-150 General questions
|
Hi Kevin,
No, I don't but I like your Quote about being a good electrician. The way I look at it is "The fact ...MrFixr55 — 08:06 AM |
Philco 38-7 Speaker
|
7K should be fine. While not a perfect match (This transformer is meant for 6V6 tubes), Antique Electronic Supply (AES)...MrFixr55 — 08:03 AM |
Who's Online
|
There are currently 2455 online users. [Complete List] » 2 Member(s) | 2453 Guest(s)
|
|
|
![>](https://philcoradio.com/phorum/images/bootbb/asb/right_arrow.png)
|