[Nathan Slingerland]

I've started in on the 38-116 that I picked up before Christmas.

Here's what it looked like to begin with:

[Image: https://farm5.staticflickr.com/4907/4635...0fba_z.jpg] [Image: https://farm5.staticflickr.com/4892/4459...fbbf_z.jpg]

Overall it's missing one acoustic clarifier but otherwise appears to be complete.
Also very little chassis rust (especially compared to the 37-690 I worked on this past Fall).  

[Image: https://farm8.staticflickr.com/7891/4569...51d9_z.jpg]

As someone has helpfully noted on the tube layout label this is a Code 125 chassis with simplified RF subchassis - more on that in a bit.

That means Philco Service Bulletin 286A. And for those who like to follow along at home:

Philco Service Bulletin No. 286A.pdf Size: 692.33 KB  Downloads: 237

Speaker

The first thing I did was to measure the field coil and output transformer resistances - all look good.  

Tubes

So there are 15 tubes on this set! That's another way of saying lots of points of failure I guess.  
After testing them on the TV7/A:

* 6L6 GC - GE - 12/25
* 6L6 GB - GE - 37/25
* 5X4 G - NU - 56/40, 55/40, broken key
* 6J5 G - National Union - 54/50
* 6J5 G - Philco - 70/50
* 6J5 metal - Sylvania - 87/50
* 6J5 metal - Raytheon - 48/50
* 6A8 metal - RCA - 48/29
* 6A8 metal - Sylvania - 44/29
* 6K7 G - Sylvania - 26/36
* 6K7 metal - RCA - 64/36
* 6K7 GT - Raytheon - 54/36
* 6U7 G - NU - 35/40
* 6N7 G/GT - Philco - 54/38, 57/38
* 6R7 metal - Philco - dead

I ordered another 6L6GB with similar test results off of eBay right away. The others that were bad I can borrow from other sets until I find replacements.

Tube Shields

Right away you can see that there are a bunch of metal tubes. The 6L6 output tubes are a GE branded 6L6GB and 6L6GC.

These 1938 tube shield bases (unlike on the 1937 models I have) are clearly designed to prevent metal tubes from being used...which just means enterprising owners / repair men hacked up the tube shield bases to allow for metal tubes to be seated anyway. Nice one Philco.

[Image: https://farm5.staticflickr.com/4886/4568...401a_z.jpg]

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[Image: https://farm8.staticflickr.com/7884/4656...c764_z.jpg]

After comparing my chassis with as many other 38-116 chassis as I could find on the Internet it's pretty clear that several of the tube shields on this one have either been...er..modified (read mangled). Or as in the case of the 6R7 and lower middle 6J5 tubes at the bottom left, removed entirely.  

For reference, here's a photo of another 38-116 chassis (someone else's) with all of the tube bases intact (missing the 6R7 tube shield):
   

Anyway, there should be a total of 11 tube shields - on all but one 6J5, the 6L6 output tubes and of course 5X4 rectifier:

• 9 square tube shields
  
• 1 large diameter round tube shield (on the 6N7)
  
• 1 aluminum tube shield (on the 6U7)
  

That last one really intrigues me. At first I thought that the one round aluminum tube shield had to be a non-original replacement. But in my search for chassis pictures I found the same round aluminum tube shield on most of them! Another clue: note that the tube shield base of the 6U7G (rearmost tube on the RF subchassis) is aluminum rather than plated tin like every other Philco tube shield on this chassis - or any other that I've seen. So I believe it's original (although was initially sitting on the wrong tube on mine). It's not called out in the parts list of the service bulletin. Perhaps someone here knows the answer to this riddle??

[Nathan Slingerland]

Here's the before picture for under the chassis:

[Image: https://farm8.staticflickr.com/7822/4651...5dc3_c.jpg]

The paper caps are almost all original. Several of the electrolytics have been replaced.

Phono Jack

Also note the addition of an after-market phono input jack (shielded wires). In order to make that work the magnetic tuning switch has been replaced with a three-position job. So Off-On-Phono. It's pretty well done actually - and finding an original switch is probably not going to happen - so leaving it in place might be the best option.

Dial Lamps

The first thing I did was to fix the dial lamps. I like to do those first so that they're not shorted - and because it's reassuring to see them glowing as I bring up a set for the first time on the variac.

[Image: https://farm5.staticflickr.com/4897/4584...7b42_z.jpg]

Electrolytics

Next I tackled restuffing the electrolytics. I used Solen film caps to replace the main filter caps parts 120 and 121 (both 8uF) as well as part 123 (8uF / 10uF). Part 70 (8uF / 8uF/ 6uF) was too small so I used Nichicon electrolytics.

[Image: https://farm8.staticflickr.com/7836/4566...4b7d_z.jpg]

[klondike98]

[rfeenstra]

I'm going to follow your thread closely cuz I'm close to starting the 37-116 I recently obtained.

[Nathan Slingerland]

Success! I brought it up on the variac and after futzing with the bandswitch a few times (probably dirty) it received decently on the broadcast band - especially considering nothing but the electrolytics have been replaced.

[Video: https://youtu.be/-1IGAtIgdIQ]

Next step will be to go through the paper caps.

One hopeful bit - the code 125 RF subchassis looks almost reasonable - I think all of the paper caps might actually be accessible enough to replace them without taking the whole thing apart!

[Ron Ramirez]

At first I thought that the one round aluminum tube shield had to be a non-original replacement. But in my search for chassis pictures I found the same round aluminum tube shield on most of them! Another clue: note that the tube shield base of the 6U7G (rearmost tube on the RF subchassis) is aluminum rather than plated tin like every other Philco tube shield on this chassis - or any other that I've seen. So I believe it's original (although was initially sitting on the wrong tube on mine). It's not called out in the parts list of the service bulletin. Perhaps someone here knows the answer to this riddle??

It is original. Why did they do this? I don't know. You would have to ask a Philco engineer of the time - and he won't answer, because dead men tell no tales.

Oh, and good luck with that RF unit. I hope you don't have the trouble that I did with the 38-690 I used to own. I went through three RF units before finding one that would work. Since you're already receiving the AM band, though, you're ahead of the game.

[Nathan Slingerland]

Today I started working through restuffing the tubular paper caps. I don't always restuff caps but on a fancy set like this I like to do it if there's a reasonable percentage of original caps present.

Here's the process I use:

1. Desolder capacitor

[Image: https://farm5.staticflickr.com/4856/3274...8eba_z.jpg]

I do them one at a time so as to not get confused.

2. Remove old capacitor from paper shell

I use a heat gun on the first setting to melt the wax. There's usually wax on the outside of the cap that will liquify while doing this - I wipe that away with a paper towel.
It's usually necessary to heat the entire capacitor - but focus most of your attention on the ends - in order to remove the old contents.

[Image: https://farm8.staticflickr.com/7880/4656...d95e_z.jpg]

[Image: https://farm8.staticflickr.com/7816/4662...c2cf_z.jpg]

I use an old glove to hold the capacitor while doing this - and pliers to pull on the leads.

3. Find a new capacitor

I generally restuff with 630V axial film capacitors that I get from renovatedradios.com or radiodaze.com

[Image: https://farm8.staticflickr.com/7921/4662...47f4_z.jpg]

4. Refill the ends

I use a foam block to hold the capacitor and place the shell around it.

[Image: https://farm5.staticflickr.com/4824/4589...d106_z.jpg]-

I use brown colored hot glue to fill the ends. I get it off of eBay shipped directly from China (link).
This hot glue is actually made for attaching hair extensions but it looks even better on a Philco radio.
It's good for this application as it's fairly low temperature and a reasonable color.  

[Image: https://farm5.staticflickr.com/4853/4662...2c33_z.jpg]

I use a cheap mini hot glue gun and fill up the end of the cap. Sometimes I use some of the old wax as filler so as to conserve hot glue.

[Image: https://farm5.staticflickr.com/4877/3965...8ec9_z.jpg]

5. Ready for another 80 years!

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I try to reinstall so that the cap is in the same orientation (outer foil notation) as original and as shown on the schematic - even though it doesn't seem to matter (and no way to tell) for modern caps AFAIK.

---

Here's the chassis after I finished restuffing (almost) all of the tubular paper capacitors on the main chassis.
I replaced the few non-original caps from earlier repairs with Philco spares that I had.

[Image: https://farm8.staticflickr.com/7865/3168...2ce8_z.jpg]

Tomorrow I'll restuff the bakelite blocks.

Initially I thought that I might be able to access all of the RF subchassis capacitors without removing it - but I later noticed that there is still one buried quite deep.
So I plan to take it all apart as per usual on these 1937/1938 sets. I'll tackle that tomorrow too.

[sam]

looks great Nathan

I did my 37-116 took apart
but folded and I got sub chassis caps  2 were a pain but doable with out unsoldering sub chassis  

sam

[Paul Philco322]

You are a perfectionist and I applaud your fine effort, I feel inadequate...................

Paul B.

[Nathan Slingerland]

Thanks Sam and Paul.

Sam - Interesting. I've heard about that method for working on these RF subchassis sets but have yet to try it. This is the link I've seen:

http://johnjeanantiqueradio.com/philco37-116.htm

Looks kind of scary to be honest! I worry what it might do to any brittle wire insulation if you're not real careful.

Anyway, I think I'll still do it the way I know for this set. At this point I've done it the desolder everything way enough times that I don't even really mind. It hurts but at least I know what to expect.  

[klondike98]

lookin good nathan

[Radioroslyn]

+1!
Tnx for the tip on the brown glue. I had looked around for some awhile back but it's was kinda pricey and didn't like the available colors. Just ordered 36 sticks for abt $7.

I did a 37-116 122 back in the mid '80s (the radio not me) didn't remove the sub chassis but got most of the caps replaced. The set worked well for several years but eventually it died. Turned out to be an unreplaced cap the the oscillator circuit has shorted. Was able to get it out with out a lot of disassembly and was restored to operating condition. Years later one of the filter went leaky and I haven't gotten around to having a look at it.

[Nathan Slingerland]

Today I restuffed all of the bakelite blocks.

Bakelite Blocks

I took some pictures of what I do - which is to desolder the block entirely. Other people work on the blocks in place. Everybody does things differently and that's OK.
I guess I prefer to remove the block in order to make it easier to install the new components and clean it up a bit. When everything is unsoldered it's also a good opportunity to check the values of any connected resistors.

Also - for working with these block I highly recommend Steve Davis's tools.

[Image: https://farm5.staticflickr.com/4827/4663...9288_z.jpg]

Step 1 - Desolder and Mark Connections

Desolder the connections to the block. I use desoldering braid to soak up the solder and wire markers to keep track of how things are connected.

[Image: https://farm8.staticflickr.com/7847/4572...7e97_z.jpg]

[Image: https://farm8.staticflickr.com/7899/3967...2122_z.jpg]

Step 2 - Disconnect Caps

Each terminal of the bakelite block is attached with a brass rivet. Wires connecting to the capacitors in the block pass through the rivets.
The blocks on this set are the variety where the rivet holes have been filled in with solder. Maybe Philco did this in an attempt to slow down the eventual degradation of the caps? Who knows.

I use a 1/16" drill bit to drill them out. If these were the blocks that have rivets that aren't filled with solder I would instead just use the screwdriver handle with a drill tool to cut the wires.

[Image: https://farm5.staticflickr.com/4908/4658...e9e3_z.jpg]

Step 3 - Heat and Remove Tar and Old Caps

Heat with heat gun (low setting) and push contents out with tool:

[Image: https://farm8.staticflickr.com/7859/4663...4dbb_z.jpg]

[Image: https://farm8.staticflickr.com/7850/4572...c20b_z.jpg]

Step 4 - Clean Up

As you can see this block is pretty dirty.

I use desoldering wick to remove any remaining solder from the terminals and also the connection points for the contents of the block (middle of each terminal).
Next I use a brass bristle brush to clean any dirt and flux off of the terminals.

[Image: https://farm5.staticflickr.com/4840/3276...4360_z.jpg]

Finally I put a small amount of Goo Gone on a paper towel to wipe off the sides. The block is almost like new at this point.  

Step 5 - Restuff With New Caps

I rely heavily on Ray Bintliff's Philco Condensers And More book (4th edition). More info can be found in the Philco Bakelite Block Condenser Data post in the Tech Section.

Just look up the part number in the index - that tells you which page the block's diagram can be found on.

[Image: https://farm8.staticflickr.com/7823/4658...81c3_z.jpg]

[Image: https://farm5.staticflickr.com/4882/4572...37d0_z.jpg]

Great! It's a dual 0.09uF block with connections as shown. I'll use 0.1uF 630V radial caps to restuff in this case.

[Image: https://farm5.staticflickr.com/4860/4572...95a9_z.jpg]

[Image: https://farm8.staticflickr.com/7904/4658...1fd0_z.jpg]

[Image: https://farm8.staticflickr.com/7875/3169...a7ff_z.jpg]

Step 6 - Reinstall

[Image: https://farm8.staticflickr.com/7818/3967...f702_z.jpg]

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The other blocks were pretty much just rinse and repeat.

[Image: https://farm8.staticflickr.com/7906/4572...ae07_z.jpg]

The only special case are the 0.015uF capacitors across the AC line to chassis where you need to use Y2 rated capacitors. They're designed to 'fail open' rather than possibly shorting out when they eventually fail. There's some good info on justradios.com.

[Steve Davis]

I would like to mention, if anyone would still like to buy the condenser block tools or an alignment tool, I can sell them directly and save you the cost of the ebay fees. They were listed in the Phorum For Sale section, but the add timed out and went away. If interested, send a PM.

Steve

[Nathan Slingerland]

Good to know Steve! Thank you again for making these available.