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Ron's RCA T7-5 Electronic Rescue
#31

Thanks Ron - I missed the earlier notes.

The set I'm working on used 20 AWG solid for much of the point to point wiring. I could not find that with 600 V insulation (mostly to match the thickness and appearance of the rubber wire) anywhere. In the end I settled on stranded, as it was available. It looks well enough, and will complete the circuit just fine.

Cheers

Ed

I don't hold with furniture that talks.
#32

Ron;
  I see what you mean about the "J' hooks, actually to me the look somewhat like the "eyes" you buy from the hardware store for attaching the wire on the back of a picture frame, very interesting way to make a terminal for an IF can out of what looks like 16 gauge wire. When  I was speaking of "J" hooking I was thinking of that quick and dirty method of attaching new components to the lead of an old component, the leads that have 70+ years of dirt, wax, and oxidation on them, and are attached to a terminal with 70+ year old solder, which is a practice that I think is best avoided if you can.
   I must confess to one more thing, though I do like Philco radios I always preferred the construction practices of RCA (also G.E, RCA, and Westinghouse in Canada) over those of Philco for servicing. I am not including the 1931-33 RCA sets in this obviously, with their layered chassis, the Philco sets in that era have the RCA style sets beat in that respect.
Regards
Arran
#33

Old trick for soldering to just about any old terminal. also works for helping ancient solder melt for removal from terminals. Take some rosin, cheap violin rosin is fine, crush it up with a hammer, and dissolve it in 91% isopropyl alcohol. Using a little artists paint brush, apply it to the old solder, and give it a few minutes to dry. It acts like new rosin flux and makes the old solder flow like new. This makes it much easier to solder new things to the old terminal, or to use solder wick and / or a solder sucker to remove it. You can also apply it to solder wick to make it absorb the solder better. I always keep a little pimento jar with this mixture on my bench.
#34

Saturday's progress, Part I

Let's Make a New Speaker Cable

This technique is also applicable to 1938-1948 Philco radios.

Take a good look at the RCA's speaker cable.

[Image: http://www.philcoradio.com/images/phorum...-5_021.jpg]

Someone cut the original speaker wires and substituted AC zip cord for the original wires, joining them at each end with wire nuts and electrical tape.

I want the speaker cable to look original. So let's do this over and do it right.

You can see the new speaker cable in the background of the photo above.

The wire I used to make this cable came from Antique Electronic Supply. They sell 8 colors of cloth covered wire, each color in a 50 foot spool, for $10.50 per spool. In contrast, Radio Daze sells unrated cloth covered wire in 25 foot spools for $10.50 per spool or $68 for all eight colors.

Hmmm...$68 for eight 25 foot spools, or $84 for eight 50 foot spools?

Yup...Antique Electronic Supply won.

When I received this wire, I discovered that their wire is the thick 600V rated wire - thicker than the unrated Radio Daze wire, which is actually the correct size for most 1930s applications.

Am I disappointed in the thickness of the AES wire? Yes. Would I buy it again from AES? You betcha! Eight rolls with double the wire length per roll for only $16 extra is a no-brainer.

Anyway...

The hardest thing to do is to remove the insulator from the end of the speaker plug. That is, it is usually the hardest thing to do. Removal of this part often involves drilling out the center rivet and when finished, resorting to glue to hold the insulator in place when finished with rewiring the plug.

Fortunately in this case, though, both insulator and rivet merely popped off...

[Image: http://www.philcoradio.com/images/phorum...-5_022.jpg]

To be continued later. It's very late and it's way past my bedtime. Icon_yawn

--
Ron Ramirez
Ferdinand IN
#35

Ron;
  Got to love those wire nuts, wrong, but still better then just twisting the wires together and covering them with 1/2 a roll of tape. As long as the new thicker wire fits through the holes in the speaker socket it will be fine. Do you know what gauge the AES cloth wire is? I'm wondering how it would compare to the stuff that Tom's Engine Barn sells, I think that the smallest they sell might be 18 Guage, but they also have more variety in colours then most places offer, such as wires with tracers on them. With regard to the rivoted on insulator there is also the option of drilling out the Bakelite and tapping the hole for a fine threaded, flat head machine screw, if the rivot had not come out.
Regards
Arran
#36

> With regard to the rivoted on insulator there is also the option of drilling out the Bakelite and tapping the hole for a fine threaded, flat head machine screw, if the rivot had not come out.

That's a good idea, Arran. I will try that the next time I have to work on one of these.

Saturday's Progress, Part 2: Let's Make a New Speaker Cable, cont.

So now we need to get the connectors out of the plug.

You should do one wire at a time so you do not get confused on which wire goes where.

I found that using a tiny screwdriver to push the connector out of the plug worked fairly well.

[Image: http://www.philcoradio.com/images/phorum...-5_024.jpg]

Be careful doing this. There is a chance that you could break off the solder tab of the connector.

Once pushed free of the plug, things look like this:

[Image: http://www.philcoradio.com/images/phorum...-5_023.jpg]

Now pull connector and the piece of old wire out of the plug.

[Image: http://www.philcoradio.com/images/phorum...-5_025.jpg]

Unsolder the old wire from the connector and you are left with this:

[Image: http://www.philcoradio.com/images/phorum...-5_026.jpg]

The solder tab needs to be at a 90 degree angle to the connector; it gets bent when you push the connector out of the plug with your tiny screwdriver.

Take a pair of needle nose pliers and carefully bend the tab back to a 90 degree angle so it looks like this:

[Image: http://www.philcoradio.com/images/phorum...-5_027.jpg]

more to come...

--
Ron Ramirez
Ferdinand IN
#37

Saturday's Progress, Part 3: Let's Make a New Speaker Cable, conclusion

Now push your new wire through the hole in back of the plug where the old wire was.

[Image: http://www.philcoradio.com/images/phorum...-5_028.jpg]

Solder the new wire to the solder tab of the connector. Cut off any excess wire. You do not want to leave hardly any excess wire/solder here at all. Leaving a large blob will interfere with getting the insulator back in place on top of the plug.

[Image: http://www.philcoradio.com/images/phorum...-5_029.jpg]

Now it's time to push the connector back into the plug.

Note that the connector will only go into the plug one way. It must be oriented correctly to go back in. Push it back in gently and it will snap in place.

[Image: http://www.philcoradio.com/images/phorum...-5_030.jpg]

Lather, rinse, repeat for the remaining wires.

[Image: http://www.philcoradio.com/images/phorum...-5_031.jpg]

[Image: http://www.philcoradio.com/images/phorum...-5_032.jpg]

Finally, replace the insulator on the end of the plug.

[Image: http://www.philcoradio.com/images/phorum...-5_033.jpg]

Voila - new speaker cable! And it looks like it came from the factory this way. Icon_thumbup

--
Ron Ramirez
Ferdinand IN
#38

Saturday's Progress, Part 4

There was no grommet in the chassis where the speaker cable came through, which likely contributed to the demise of the original cable.

There is one there now.

[Image: http://www.philcoradio.com/images/phorum...-5_034.jpg]

I replaced some above-chassis wiring, three resistors, and two mica caps. I also cleaned the top of the chassis as best as I could using a can of the orange hand cleaner with pumice. It wasn't really rusty, but was very dirty/grimy/grungy.

I removed another electrolytic can as well. But try as I might, I could not get the nut of the third electrolytic to budge...so I made an executive decision to rebuild that can in place.

Here's how the top of the chassis now looks:

[Image: http://www.philcoradio.com/images/phorum...-5_035.jpg]

Most of the attaching screws for the coil/IF transformer cans are missing in the photo above. They have been sitting in Evapo-Rust overnight, along with the grid cap connectors. After their Evapo-Rust bath, I will reattach those screws and lockwashers.

Here's how the bottom of the chassis now looks:

[Image: http://www.philcoradio.com/images/phorum...-5_036.jpg]

I'm seeing the light at the end of the tunnel on this one. I still need to do the following:

Attach the wires of the new speaker cable to the proper points under the chassis
Replace the two-section Candohm
Replace one more paper cap
Restuff all three electrolytic cans
Add a new AC cord
Replace another wire or three
Do something about the broken-off Fahnestock clip/Phenolic insulator for the antenna terminal

...and that should be it other than the dial scale. It looks like the dial pointer is going to be fun to remove...not. It may very well be rusted in place. I'll try some PB Blaster and see if that will help.

--
Ron Ramirez
Ferdinand IN
#39

Looking good Ron Icon_thumbup 

I bought my first batch of cloth covered wire from Radio Daze, didn't think to look at AES back then.  Tom's Engine Barn may also a good resource to check out.

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#40

Thanks John. I bought some wire recently from Tom's Engine Barn for that 38-690 project and was very pleased with it. The smallest wire they carry is 18 gauge, though.

I was surprised to find that AES still sells cloth-covered wire. I was under the impression that they had switched about 99.5% of their business to the guitar amp crowd. It might be more like 85% guitar amp stuff now Icon_wink

--
Ron Ramirez
Ferdinand IN
#41

For openers today, I removed the two-section Candohm.

[Image: http://www.philcoradio.com/images/phorum...-5_037.jpg]

The rivets which held this on the chassis were very stubborn and difficult to remove. I ended up having to grind both sides to get them out.

Next, I prepared two of the three electrolytic cans for restuffing.

[Image: http://www.philcoradio.com/images/phorum...-5_038.jpg]

[Image: http://www.philcoradio.com/images/phorum...-5_039.jpg]

Yes, the second one is a Philco part. The can that was on the chassis was a replacement, with wires coming out on the end. The original electrolytic had a solder lug on the end. This Philco electrolytic had a solder lug on the end and has a threaded stud for mounting, so this will result in an original-type unit. Once I polish the can, the lettering will disappear and no one will know the difference but me (and you guys reading this thread). Icon_wink

After doing all of this, I remembered the parts that had been soaking in Evapo-Rust overnight. I washed and dried them, and here are the results:

[Image: http://www.philcoradio.com/images/phorum...-5_040.jpg]

The screws look great, as do the lockwashers.

Unfortunately the grid caps still look grungy. There was a good reason for that - I discovered that just enough grunge had come off in the Evapo-Rust bath to reveal that the grid caps are brass, not steel.

So the grid caps are now soaking in ammonia.

I attached some more terminal strips to the chassis to replace the two-section Candohm.

[Image: http://www.philcoradio.com/images/phorum...-5_041.jpg]

[Image: http://www.philcoradio.com/images/phorum...-5_042.jpg]

I have a problem. I misread the value of R20 - it is 13K, not 15K. (I had ordered a 15K resistor.) Icon_sad I'm tempted to use the 15K anyway, but until I make up my mind, this is how it will remain.

My next job will be to restuff and reinstall the two electrolytic cans currently on the bench and waiting. As for the third can, I will have to rebuild it on the chassis as I mentioned in a previous post.

--
Ron Ramirez
Ferdinand IN
#42

Nice work Ron. Icon_thumbup  There is a lot of work and thought there, even if the chassis is fairly open.
#43

Ron;
  I don't know if this will work on electrolytic filter can #3 or not but I see that it has a stamped steel nut, sort of like a tinnerman nut. If it refuses to come off you should try prying the ears, on the inside of the nut, away from the threads by inserting a screwdriver or awl between the ears to lever away the tension, you only need to go about 1/2 way around to do it. It may not work but it's worth trying if it makes it easier to work on the can. With regard to the Philco can I would be inclined to save it for the next Philco that needs it, and find a generic substitute like an old Aerovox, or just leave the labeling as it is, it's part of the radio's history.
Regards
Arran
#44

No radio work last night, had to mow the grass.

Tonight, I managed to mostly get two of the three electrolytic cans restuffed.

Here's one:

[Image: http://www.philcoradio.com/images/phorum...-5_043.jpg]

and the other:

[Image: http://www.philcoradio.com/images/phorum...-5_044.jpg]

and now both, mostly finished save for allowing the glue to dry on the top caps:

[Image: http://www.philcoradio.com/images/phorum...-5_045.jpg]

It was tricky to figure out how to feed a negative lead through the bottom of the can so that the nut could still be reattached. The wires are rather close together, but at least the positive leads are well insulated so it should not be an issue. The negative leads are also insulated, but their insulation is not as thick as that of the positive leads.

Arran, I might try your suggestion of attempting to work something between the "ears" of the nut on the third electrolytic - if it doesn't work out, I will still rebuild it in place.

--
Ron Ramirez
Ferdinand IN
#45

Tonight I polished the two electrolytic cans and reinstalled them on the chassis.

[Image: http://www.philcoradio.com/images/phorum...-5_046.jpg]

One of them is even hooked up now - see lower left of the photo below.

[Image: http://www.philcoradio.com/images/phorum...-5_047.jpg]

And Arran, I did try your suggestion on the "ears" of the nut holding the third electrolytic. After considerable hammering and bending, I was finally able to remove both nut, fiber washers, and electrolytic.

[Image: http://www.philcoradio.com/images/phorum...-5_048.jpg]

[Image: http://www.philcoradio.com/images/phorum...-5_049.jpg]

As you can see below, the threads at the bottom of the electrolytic can are badly mangled. I know that I caused some of this damage, but I believe the threads were already bad - which is why the nut refused to budge previously.

[Image: http://www.philcoradio.com/images/phorum...-5_050.jpg]

After considerable searching through my stash o'stuff, I managed to find one more stud mounting electrolytic can so I will be able to replace the original can. This is C35, 18 uF. I'll save this can for future use in a Philco with clamp mounting, where the damaged threads will not matter.

Hopefully I can manage to squeeze both 10 uF and 8.2 uF Solen Fast caps into the replacement can.

We shall see...

--
Ron Ramirez
Ferdinand IN




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