[462ron]

I don't understand why the electronics industry needs to make reading the value of a cap such a chore. I mean, what was wrong with the old way of writing .15mfd. on a cap instead of 154? This new way is more confusing, more chance of making a mistake! They have to print numbers on it anyway so why the need to complicate things? Just a pet peeve of mine!

Ron

[Jeremy S]

Thanks for sharing the brown hot glue stick source. In the past I used normal white hot glue and would top the end of the caps with a little bit of bees wax. I like your method much better!

For the butchered tube shield bases check with Gary at Play Things of Past. I had the same issue on my 38-116 and Gary had several of these bases at the time.

[rfeenstra]

Nathan, you're inspiring me to start the 37-116 I acquired in December as my next project.  I'm taking lessons.  Looks to be a fairly clean chassis.  Haven't look under the hood as yet to see if there has been any molestation. Don't know how much difference there is from your 38-116 but it looks very similar.

           

[Nathan Slingerland]

@r462ron  -    yeah not so easy for us poor humans. I imagine they did that due to space constraints. It also gets more error-prone to count zeros rather than significant digits + multiplier. Think trying to separate 0.00047uF from 0.0047uF - as opposed to 471 from 472. Of course they could label in units (pF/nF/uF etc.) which would make the zero problem better.

@Jeremy S - Yes! BTW - thank you for your great 38-116 restoration page. You really put in some work on that one and the result was amazing. I do have some replacement tube bases. On the RF subchassis I was able to bend them back into more or less original shape. I am still thinking about what to do with the bent bases on the main chassis - mostly the best way to attach them. I see you used 6-32 flathead machine screws which seems like a good choice. The only limitation I can see is for grid cap wires that pass through the rivets - would have to drill a new hole for those I guess.

@rfeenstra - That's the idea! I have been trying to document everything to help with your 37-116 restoration since you said you were thinking about starting it. I've previously restored a 37-116 and the two sets are quite similar although I would say the RF subchassis of the 37-116 is a bit more difficult (sorry!) as it has more caps buried in the middle of the bandswitch. The best advice is to just go really slowly and carefully and take a break if you're feeling impatient. The 37-690 uses the same RF subchassis as the 37-116 - so you can see pictures of that in my 37-690 restoration thread. There are a number of other good threads on the 37-116 - so be sure to read through as many as you can find. Your 37-116 looks to be in very nice shape.  

[Nathan Slingerland]

OK - Once more unto the breach, dear friends...

RF Subchassis

Step 1 - Label and Desolder Connections to RF Subchassis

[Image: https://farm8.staticflickr.com/7875/3169...1e57_z.jpg]

[Image: https://farm5.staticflickr.com/4862/3169...10ae_m.jpg] [Image: https://farm8.staticflickr.com/7847/4572...5ef9_m.jpg]
[Image: https://farm8.staticflickr.com/7809/4658...f8f6_m.jpg] [Image: https://farm8.staticflickr.com/7906/4663...d3cb_m.jpg]
[Image: https://farm5.staticflickr.com/4835/3967...29b0_m.jpg] [Image: https://farm8.staticflickr.com/7886/4572...a40a_m.jpg]
[Image: https://farm8.staticflickr.com/7851/3169...6363_m.jpg] [Image: https://farm5.staticflickr.com/4888/4658...9db3_m.jpg]

Step 2 - Remove Lights and Front Panel

[Image: https://farm5.staticflickr.com/4913/4658...d5cd_z.jpg]

[Image: https://farm5.staticflickr.com/4887/4658...3d7a_z.jpg]

[Image: https://farm8.staticflickr.com/7801/4658...b081_z.jpg]

Step 3 - Remove RF Subchassis

Remove the screw at the back of the RF subchassis.

[Image: https://farm8.staticflickr.com/7922/4591...2c02_z.jpg] [Image: https://farm8.staticflickr.com/7852/4658...50f5_z.jpg]

Now carefully (!) tilt the whole thing forward.

[Image: https://farm8.staticflickr.com/7809/4591...0310_z.jpg]

[Image: https://farm5.staticflickr.com/4817/3169...1109_z.jpg]

Step 4 - Remove Sides and Restuff Caps

[Image: https://farm5.staticflickr.com/4889/4591...4134_z.jpg]

On some of the RF subchassis sets the capacitors are so buried it's also necessary to slide out the shaft and work on each section individually.
Fortunately the 38-116 isn't quite that bad - all of the caps are accessible without fully disassembling the RF subchassis.

And don't forget this guy!

[Image: https://farm8.staticflickr.com/7870/4663...6025_z.jpg] [Image: https://farm8.staticflickr.com/7834/3169...b089_z.jpg]

Step 5 - Bandswitch

While I had everything apart I applied some DeOxit to the bandswitch contacts.

[Image: https://farm8.staticflickr.com/7872/3171...f1d1_z.jpg]

Step 6 - Back Together

[Image: https://farm5.staticflickr.com/4834/3969...93b5_z.jpg]

Reinstall the RF subchassis. I also replaced the rubber mounts using replacements from renovatedradios.com.

[Image: https://farm8.staticflickr.com/7882/4665...ecc3_z.jpg]

And resolder all those wires.

[Image: https://farm5.staticflickr.com/4845/3969...6a40_z.jpg]

Step 7 - Power Up

Reconnect the speaker, power it up....and....it works!  

The bandswitch works much better.

---

The set is fully recapped now and is pulling in lots of stations but definitely will benefit from being realigned.

I probably should rebuild the linkage between the tuning condenser and the dial - it's quite stiff and unsymmetrical.

[Image: https://farm5.staticflickr.com/4917/3171...13f9_z.jpg]

There's also the mangled tube shield bases. Also need to clean and reinstall the dial.

And soak some parts in Evaporust.

[Image: https://farm8.staticflickr.com/7837/3278...4a1c_z.jpg]

[rfeenstra]

Nathan, the photo of the coupling shows a fair amount of "contamination" on the plates of the tuning cap.  Do you clean those?  If so, how?  If not, does it affect the performance of the radio?

[amptramp]

Excessive dirt, corrosion or stuff like tar from a smoker are bad for performance of a tuning capacitor.  There are small make-up applicators that are suited to applying cleaning chemicals in narrow spaces.  Even if you don't get it all off, it will clear dust bridging the rotor and stator plates and that may get rid of scratchiness during tuning.  Alcohol or various types of contact cleaner would work here.

After this, you clean off the bearings and lubricate them and then you clean the shorting fingers that ride in the groove in the tuning shaft.

Make sure you have contact across the straps that ground the shield sections between the capacitor sections.

Be sure the fibre pieces that hold the stator are free of dust.

[Nathan Slingerland]

Thanks for the info amptramp. And please don't worry guys - I'm on it.

I would say that it looks worse in that pic than it really is. Performance also doesn't seem to be affected. But I'll see what I can do and report back.  

[Nathan Slingerland]

I've been working on repairing the dial. Here's what it looked like:

[Image: https://farm5.staticflickr.com/4827/4565...8f07_z.jpg]

You can see the previous repair to reconnect the inner ring to the dial using some glued on paper strips. The inner ring is also broken.

Goo Gone is my go to for cleaning dials. It was also good for removing the prior repair:

[Image: https://farm8.staticflickr.com/7831/4594...97b6_z.jpg]

My plan was to use epoxy to repair the inner loop first - then attach it back to the main dial.
I used sandpaper to roughen up the edges where I would glue things.

[Image: https://farm5.staticflickr.com/4894/4596...f011_z.jpg]

[Image: https://farm5.staticflickr.com/4804/4668...4345_z.jpg]

I then used push pins to position the pieces to be glued.

[Image: https://farm5.staticflickr.com/4826/4577...83f1_z.jpg]

I let the inner loop set for an hour (this is 5-minute epoxy) - then I glued it to the main dial in the same way:

[Image: https://farm8.staticflickr.com/7886/4668...006e_z.jpg]

I'm happy with how it turned out as the repair seems sturdy and less obvious than the prior repair.

Tonight I reassembled everything.

[Image: https://farm5.staticflickr.com/4888/3175...d195_z.jpg]

[sam]

nice work Nathan

[tbone]

I love how your radio turned out. It’s nice to watch someone take their time and do a top notch job. Nice job on restuffing the caps,just like new only better insides

Fixing the dial is something I’m all too familiar with. My 38-690 dial had a crack on the inner ring and the dial was free spinning when I got it. I super glued mine. Then I found that someone made another notch to situate the dial differently on the assembly instead of repairing the mechanism properly.
The factory notch was chipped so the dial would not stay on the mark. I used a couple of thin strips of a paper material between the dial ring and the drum to hold it in place better. A little more tension was all it took to keep the dial in place.

[Nathan Slingerland]

Thanks Sam! Thanks Tony!

Automatic Tuning Flex Coupling

I've been working on rebuilding the automatic tuning flex coupling.

[Image: https://farm8.staticflickr.com/7839/4584...0bb9_z.jpg]

Here it is removed from the tuner:

[Image: https://farm5.staticflickr.com/4852/4603...0998_z.jpg] [Image: https://farm8.staticflickr.com/7920/3181...59a8_z.jpg] [Image: https://farm5.staticflickr.com/4865/4603...3504_z.jpg]

You can easily see that the old one is stiff and cracked. That makes the tuning mechanism hard to turn unless the RF subchassis and automatic tuning dial are perfectly aligned along their axes. There needs to be some flex in the system in order  for the dial to always tune smoothly.

The first stop was to visit the excellent article in the Philco Library's tech section on exactly this topic. It was a great source of ideas and inspiration - but I ran into a few things that prevented me from just doing things exactly the same.

I disassembled the coupling by drilling out the rivets:

[Image: https://farm5.staticflickr.com/4888/3181...8ddb_z.jpg]

The resulting pieces:

[Image: https://farm8.staticflickr.com/7891/4603...6af8_z.jpg]

Hmmm... a few too many pieces actually! The metal parts are made of a pretty brittle material and I broke the thin center piece while I was trying to push out the rivets.  

[Image: https://farm5.staticflickr.com/4834/4670...5ed3_z.jpg] [Image: https://farm5.staticflickr.com/4822/3184...de1d_z.jpg] [Image: https://farm8.staticflickr.com/7829/4676...a57c_z.jpg]

In the mean time - ordering the cloth impregnated neoprene sheet. I found a sheet with similar specs from zoro.com - actaully eBay.

[Image: https://farm5.staticflickr.com/4894/3288...1bca_z.jpg]

What I didn't think about too carefully ahead of time was the following:

After disassembly the next step was to cut new rubber disks from the sheet of material. This was done with a gasket circle cutter and a punch for the rivet holes.

I don't own either of those tools. Always on the lookout for an excuse to buy a new set of tools I researched it but it looked like nice gasket circle cutter (especially 2" diameter) would set me back some $$$. So I decided instead look around for a similar precut circular gasket. I should've done that first as I found just the thing at my local hardware store!

[Image: https://farm5.staticflickr.com/4816/4586...7743_z.jpg]

While it's not reinforced with cloth like the original it looked robust enough to give it a shot. I went with the 1" ID, 2.25" OD neoprene washer. It's about the same thickness as the original.

I picked up some 5/8" long screw posts (aka Chicago screws) to replaced the long drilled out rivets:

[Image: https://farm8.staticflickr.com/7837/3981...3a3b_z.jpg]

I used one of the old rubber washers as template and drilled holes in the new ones:

[Image: https://farm8.staticflickr.com/7835/3290...544d_z.jpg]

I attached the outer set screws pieces with 3/16" x 3/8" pop rivets:

[Image: https://farm5.staticflickr.com/4901/4678...4a08_z.jpg] [Image: https://farm8.staticflickr.com/7896/3184...51f5_z.jpg]

I used finishing washers as the spacers which keep the two washers apart (part of the original piece that broke).

[Image: https://farm8.staticflickr.com/7862/4586...c89e_z.jpg]

and recreated the middle piece from aluminum stock (~0.060" thick).

[Image: https://farm5.staticflickr.com/4851/4585...0a90_z.jpg]  [Image: https://farm8.staticflickr.com/7854/3183...eecb_z.jpg] [Image: https://farm5.staticflickr.com/4848/4678...a5c7_z.jpg]

And all the pieces put together:

[Image: https://farm8.staticflickr.com/7823/4605...09d6_z.jpg] [Image: https://farm5.staticflickr.com/4873/4673...9d11_z.jpg]

And reinstalled:

[Image: https://farm5.staticflickr.com/4808/4673...0fee_z.jpg] [Image: https://farm8.staticflickr.com/7880/3184...8cd8_z.jpg]

It seems like it works quite a bit more smoothly and the tuning mechanism turns easily. We'll see for sure once the dial is reinstalled.  

[klondike98]

Excellent!!

[EdHolland]

It is a pleasure to read and view this excellent work, presented in such great detail.

Hats off to you, Sir!

[rfeenstra]

Well, you inspired me to start my 37-116!  Decided to start the sub-chassis first and have that finished.  Had to disassemble to get to all the caps and check the resistors.  I'll start another thread to note the progress.