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Philco Canada 35A or 41-712 Tropic - Printable Version

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RE: Philco Canada 35A or 41-712 Tropic - Jeremy S - 11-25-2014

I just recently started replacing most of them as I go through a set. For years I only replaced those that were out of tolerance. Replacing them all doesn't sound like a bad idea.

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 11-25-2014

No, it really isn't - after all, these radios and the components inside aren't getting any younger, and as they continue to age, more problems develop that would not have been considered even ten years ago. Mica capacitors are one example. Until recently, you wouldn't even think of replacing a mica unless it was proven to be bad. Now even mica caps are sometimes starting to "show their age." And this will only get worse over time.

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 11-25-2014

...to paraphrase an old hit song...

What A Diff'rence An Alignment Makes...

[Image: http://www.philcoradio.com/images/phorum/41-712/Image00013.jpg]

Philco apparently expected the service man to align the set inside the cabinet. But there is a problem with that - when in the cabinet, it is difficult if not impossible to reach all of the adjustment screws.

So I improvised - I took a photo of the front of the radio, focusing on the dial scale. Then, using Paint Shop Pro, I made a negative image of the scale, printed it, and temporarily taped it to the dial back plate for alignment purposes. This really made performing the alignment much easier. Icon_thumbup

The alignment was way off. Once the IF transformers were adjusted back to the proper 455 kc frequency, the AM band was then way, way off. A local station (WITZ, 990 kc) was coming in around 650. I could no longer hear my SSTRAN which is set at 660.

But once I went through the entire procedure, I not only managed to get the AM band more or less back on track (pun intended), the problems I initially experienced with very broad tuning at 660 and oscillation from 670 to about 750 kc disappeared. All three bands really came to life once the alignment was completed. As with every Tropic I have worked on so far, this one is very sensitive and is now an excellent performer.

Now I still need to clean that switch, and replace the antenna and ground leads...

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 11-25-2014

Antenna and ground leads replaced with new cloth-covered wires that are the same color as the originals (green for antenna, black for ground).

Off-on-tone switch cleaned. Using my DMM, I can see that the tone control is functioning as it should, yet I still hear no difference in tone when switched from "high" to "low". Possibly a bad cap or two in the tone control circuit?

Whatever. I've buttoned it up, put it back in the cabinet, and set it aside until the better speaker arrives. At that time, I will revisit the tone control circuit.

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 12-10-2014

35A Revisited:

Sam was kind enough to send along a 41-240 speaker that is in excellent condition. Many thanks, Sam! Icon_thumbup

[Image: http://www.philcoradio.com/images/phorum/41-712/Image00014.jpg]

[Image: http://www.philcoradio.com/images/phorum/41-712/Image00015.jpg]

The 41-240 speaker is part no. 36-1510-4 while the 35A speaker is part no. 36-1504-something. Both appear identical and are electrically identical as well.

So after a few minutes of surgery, the transplant was complete:

[Image: http://www.philcoradio.com/images/phorum/41-712/Image00016.jpg]

The "new" speaker sounds excellent. Mind you, the original speaker looks bad but also sounds good, so I'll hold it for future use.

While I had the chassis out, I did take another look at the tone control. Even manually shorting out the junction of caps (40) and (41) (on the 41-712 schematic) had no effect on tone, so I'm thinking either (40) or (41) is open. But I decided against going any further - the radio plays very well as is, so I put it all back together and placed it back on the shelf with its Tropic brethren.

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 12-11-2014

After I had it put back together, something I had noticed about one end of cap (40) kept bothering me, so I took it back to the basement workbench, took it apart again, and had another look.

You guessed it - I did not have the end of (40) that goes to the plate of the 7B5E output tube connected correctly. DUH! Icon_crazy

Once that end of (40) was soldered to the plate of the 7B5E, the tone control began working correctly.

So now the 35A is back together again, back on the shelving unit in my home office again, and is totally complete. Icon_thumbup

RE: Philco Canada 35A or 41-712 Tropic - Eliot Ness - 12-11-2014

(12-10-2014, 12:04 PM)Ron Ramirez Wrote:  While I had the chassis out, I did take another look at the tone control. Even manually shorting out the junction of caps (40) and (41) (on the 41-712 schematic) had no effect on tone, so I'm thinking either (40) or (41) is open. But I decided against going any further - the radio plays very well as is, so I put it all back together and placed it back on the shelf with its Tropic brethren.

(12-11-2014, 07:42 AM)Ron Ramirez Wrote:  After I had it put back together, something I had noticed about one end of cap (40) kept bothering me, so I took it back to the basement workbench, took it apart again, and had another look.

You guessed it - I did not have the end of (40) that goes to the plate of the 7B5E output tube connected correctly. DUH! Icon_crazy

Once that end of (40) was soldered to the plate of the 7B5E, the tone control began working correctly.

So now the 35A is back together again, back on the shelving unit in my home office again, and is totally complete. Icon_thumbup

I knew you wouldn't leave it on the shelf in that condition Icon_wink

Glad you got it taken care of.... I've enjoyed your work on the Tropics, a set I was previously unfamiliar with, thanks!

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 12-11-2014

Thank you, John! Icon_biggrin


Yes, after I had reassembled the set and put it back on the shelf, I started thinking about cap (40) and my thought was, The other end of that cap didn't look like it was soldered in the right place. So I disassembled the set again to find that, yes, I had made a mistake. Icon_eek It happens to all of us from time to time. Now the chassis is all done and all correct.

Well, I misspoke when I said it is totally complete. Someone painted the cabinet ivory. While it actually looks neat like this, it really bugs me because it isn't correct. I wouldn't mind it being ivory if it were, say, a Philco 41-230T or one of the farm sets like a 41-90CB or 42-121CB.

Hmmm...I have a 41-230...maybe a cabinet switcheroo is in order... Icon_idea

RE: Philco Canada 35A or 41-712 Tropic - Ron Ramirez - 01-09-2019

Just over four years on...

I was just looking at this thread and I see that I never did tell you what I ended up doing about the cabinet.

I found a 42-121CB at an antique shop in Corydon, IN a year or two after I finished the chassis of the 35A/41-712.

The 42-121's cabinet was in good shape. I did switch cabinets between the 42-121 and the 35A, so now the 35A has a nice looking, polished cabinet. I gave the 42-121 with the painted cabinet to Sam a couple years ago.

Here's the 35A as it has looked since the cabinet switch...

   

RE: Philco Canada 35A or 41-712 Tropic - Greggshere - 01-09-2019

Looks really nice Ron.