Started stuffing the electrolytics. I've stuffed this type before but the previous time they were missing the positive terminal lug. This time they are still intact so here's a set of photos for how I stuff 'em. This will be old hat to many but perhaps some folks haven't seen it done. There are other ways to do this I'm sure.
[Image: https://www.dropbox.com/s/l6w22ofjckfjgx....jpg?raw=1] I cut off the top of the can using a utility knife. I place the can on the workbench and roll the can under the knife blade working my way around the can. I places a dent in the can at first but after a few revolutions the blade penetrates the can.
[Image: https://www.dropbox.com/s/le3kgcaqgp6mzc....jpg?raw=1] Pull the guts out.
[Image: https://www.dropbox.com/s/r39zay9t06j4km....jpg?raw=1] Next I work the lug off of the aluminum rod. It is press fit on and with some effort you can get the utility knife blade worked in and pry it off. BE CAREFULL--easy to slip and cut yourself on this step!!! Wear leather gloves and safety glasses.
[Image: https://www.dropbox.com/s/qdgubf94lrkakm....jpg?raw=1] Pull the aluminum rod out of the can with a little twisting and pulling.
[Image: https://www.dropbox.com/s/sp88g2eo24x4vm....jpg?raw=1] Drill a hole in the bottom of the can to allow the negative lead for the cap to come through.
[Image: https://www.dropbox.com/s/4kgnlzdwbtrw5t....jpg?raw=1] Get your new cap, a piece of heavy gauge copper wire (or you can reuse the aluminum rod but you can not solder to aluminum so you have to use a screw to fasten the positive lead to the rod), and some hook up wire with about 2" stripped on one end and a 1/4" on the other
[Image: https://www.dropbox.com/s/u4dtilvftwuvmk....jpg?raw=1] Attach the electrolytic cap's positive lead to the copper wire and the negative lead to the hook up wire at the 1/4" stripped end.
[Image: https://www.dropbox.com/s/jc24j2d146t6a9....jpg?raw=1] I wrap the assembly with electrical tape to give it some stability and keep the wires steady. You could pot it as well. then feed the hook up wire through the hole you drilled and the copper wire through the center hole in the can. Wrap the 2" of hook up wire around the base of the can. This will make contact with the chassis for ground (or if the can connects to the transformer center tap there will be some rubber washers that keep the can off the chassis but the hookup wire will still be in contact with the can so you can connect the can as the cap negative to the center tap.) Then I recrimp the lug onto the copper wire. Needle nose pliers will start the crimping but I then used some wire cutters to press a deeper crimping indent at the top and bottom of the lug. Hopefully it will stay. Then I check the set up to ensure there isn't a short in the assembly. I'll glue the top back on the can with some JB Weld after the radio is working again.
I hate it when someone's been in the set and soldered over the little wire holes in the bakelite blocks. This one is the line bypass filter. The bumblebee cap will be replaced with a restuffed philco cap.
[Image: https://www.dropbox.com/s/q70fmaa8tfm87e....jpg?raw=1]
klondike98 Wrote:I hate it when someone's been in the set and soldered over the little wire holes in the bakelite blocks.
Philco did that at the factory from mid-1936 (1937 models) on. Right now I can't remember if they did that with the first year's "universal" bakelite blocks or not. Yup, it's a pain for us now, but the Philco people never envisioned anyone ever emptying and restuffing these blocks.
Yes, it was not in great shape but should come back to playing status. I debated on whether to restuff caps and make simulated resistors since I have to replace a moulded wirewound resistor that I won't try to reproduce but decided to do so anyway.
Not to hijack your thread. But I have a 39-30, and I'm just sort of curious if yours has the same factory changes as mine did.
I've seen at least 2 other threads describing this change (picture below). Basically it seems Philco took AVC off the IF grid. They disconnected the secondary of the 2nd IF from the AVC line, and instead tied it in to the CT bias voltage resistor via a 490k resistor and they added a .05uF bypass cap. If you look at the schematic for the 39-36 (which is almost the exact same circuit/chassis, but shoved into a console), the schematic documents this circuit from the factory.
The other 2 changes are in the tone circuit. I've seen one other post about R25 (hanging off the tone tap). It's listed as 32k. But in the radio it was 51k from the factory, as was mine.
And the other change is also in the tone circuit, but I haven't seen anyone mention. C39 on the tone control is listed as .006 uF, but was .008 uF from the factory. Although, that is probably such a small difference, it doesn't matter much. Edit: Actually, I now see this was the cap that someone put a bumble bee in on yours.
As for my 39-30, I'm chasing down a distortion issue. There is a thread over at ARF that some people have been helping me with, but no luck so far. I had a thread here too earlier in the year, but never got much traction. I'd love to compare some notes with you when you finish yours up to see if I can find any discrepancies on mine.
(This post was last modified: 11-16-2015, 11:45 PM by Nick3092.)
I'll have to check on the other changes you mentionef the next time I'm in the shop but yes R25 is a 51k resistor, I noticed it today and was all set to change it out because it was high, 50k....until I realized they had actually installed the 51k.
Have been recapping and recarbing. Had to replace the 280 ohm wirewound resistor (#45) which showed obvious overheating. The case was bulging and cracked (as was the 70 ohm (#46)). Surprisingly it still measured 304 ohms in the circuit and 340 after getting it out...incredible.
[Image: https://www.dropbox.com/s/8xbcc3d2yzu16u....jpg?raw=1]
Three of the 6 resistors are replacements and all the caps are stuffed. I lost all the printing on the one cap in the lower right as I was pulling the guts out. Here's the 70 ohm 1/2 watt replacement in the final stages of painting. I used the same steps as in the 39-25 posts.
[Image: https://www.dropbox.com/s/u34olqvh2ou8sm....jpg?raw=1]
Finished the recap, recarb and much of the rubber wire. Fortunately the power transformer was a replacement and had cloth wire. This isn’t the prettiest chassis but it’s better than it was. A 1 amp fuse was also added to the hot side of the power cord, seen in the lower left corner.
[Image: https://www.dropbox.com/s/wvzlrvay44tua5....jpg?raw=1]
After reinstalling the tuner cap with new rubber mounts, dial scale bracket, restringing the dial and putting the tubes back in she fired up and was able to pull in the local talk radio show on 630AM. The push button for that range was also able to be tuned to 630 so that is working as well. Needs alignment and I need to find some square tube shields as the ones on this puppy are missing but I’m tickled it’s working again. Thanks to Nathan, I was able to get a replacement speaker and not have to try putting a new voice coil/cone into the one that came with the set. Cabinet work will have to wait until spring time but that's a different thread.
[Image: https://www.dropbox.com/s/nm15ixb0tfw4ij....jpg?raw=1]
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