[klondike98]

I took a break from the Z 8G005 I’ve been struggling with to take a look at the Philco 50 chassis (schematic link) that I picked up at Kutztown.  The speaker (an 8” S type) cone is in decent shape, but unfortunately the output transformer primary is open.  The voice coil and field coil both show continuity.
Power transformer also seems to be OK at least as far as continuity goes.
Leads 1 &2 = 12 ohms
Leads 8 & 10 = 540 ohms
Leads 6 & 7 = < 1 ohm
Leads 3 & 5 = < 1 ohm

The ON-OFF switch seems to be permanently open

[Image: https://www.dropbox.com/s/heydx7v48a06ht....jpg?raw=1]

The chassis is not as bad as I thought it was going to be; the tuning cap is a bit rusty, there are some chassis rust spots and it’s pretty dirty.  The usual mouse nest and sunflower seed shells were in the cabinet under the chassis.  

[Image: https://www.dropbox.com/s/wl12gx50jxma6r....jpg?raw=1]

[Image: https://www.dropbox.com/s/1doa8c7nq43fbk....jpg?raw=1]

[Image: https://www.dropbox.com/s/32avswvwlnecrw....jpg?raw=1]

[Image: https://www.dropbox.com/s/nosn6gdqh3fm8v....jpg?raw=1]
Next some general housekeeping and check the coils.

[morzh]

I wonder whose bright idea it was to put the power xfmr under the chassis.......gross incompetence.

Output xfmr bad is not too bad. I always take that vs field coil open.

[klondike98]

That design keeps everything nice and warm

[morzh]

Yep. Good unheated log cabin winter radio, will sure keep all the parts above freezing.

[Radioroslyn]

Did you say nice or mice??
I had one not too long ago. PT was replaced, nowdays that's a pain cause the set uses 2.5v heaters.  I think it has louvers cut into the wooden bottom to help air circulation and makes a lovely entrance for the mice. As for the open output transformer it needs to be about 7K (plate load not dc resistance) on the primary. If you have a junk Philco transformer that was used on a set with a single (not married) 47,42, or 6F6 any of these will work well. All have the same load resistance.

Terry

[klondike98]

No vents in the bottom of this cabinet...its the version that used a 70 cabinet with a front cut for the 50 chassis and the bottom redrilled to fit. The chassis itself has no sides and parts of the front cut out, I assume for ventilation....and it was mice ...

[klondike98]

Started into this set and with a liberal dose of deoxit I was able to bring the rotary ON-OFF switch back to working order  

[Image: https://www.dropbox.com/s/58ilyfziod892u....jpg?raw=1]

[klondike98]

I've stuffed several types of electrolytic cans but never this style of Sprauge.  What's the best approach to opening it up and after putting the new cap in, sealing back together?  There is no insulating sleeve to hide the cut you make so I'm assuming the best spot to cut is on one edge of the indented section.

[Image: https://www.dropbox.com/s/tgum1p0m9713gn....jpg?raw=1]

[KCMike]

I would try cutting it where the indented side closest to long /top side of cap is. That will give you some material to push up into the long part of can. You can also using a piece of pvc pipe on the inside to help glue the lower and upper pieces together, pushing a little of the indent part back into can to hide the cut.

[morzh]

John

One opened wnd gutted, vinegar cleans the oxidation well. I just immerse the can in vinegar and keep it there.

As for cutting.....pick one. I cut at the bottom, at the top edge of the groove. Then you can either 1) use a pipe of a suitable diameter to glue it back (groove will mask the cut somewhat) or 2)smush the groove a bit and push it inside the top part. This will result in no wide groove left with the faitly neat narrow separation of top and bottom.

This will also give you the ability to break the central post at the very base so you could drill through it. The post cannot be reused (aluminum) but a nice looking copper riveted push-on Quicker connect could be put in place and then inner cap's plus soldered to it.

[klondike98]

Thanks guys!  I also got some advice from Phlogiston and decided to try his technique.  Starts off by grinding the crimped end of the can.  This can is nickel plated over copper so its pretty soft.  Grind enough that when looking sideways on the can, the curved edges of the crimp are gone.  I used a Dremel tool.  [WEAR SAFETY GLASSES] Then using the large nut and locking pliers you work the plastic/bakelite base out of the can.  I had to put the nut on and also turn it with a wrench a bit to start the base moving in the can.  Then I was able to work/pull the base out with a little grunting...ok, a lot of grunting.  The center aluminum threaded bolt and electrode comes out of the bakelite and will be replaced with a modern bolt.  Now for the second one ....

[Image: https://www.dropbox.com/s/9tf3kn4lrmrn0l....jpg?raw=1]

update: after opening the second can, I'd suggest NOT trying to turn the bakelite piece with the wrench.  There are actually two pieces to that part and you can wind up turning the one with out turning the other.  You can see them in the photo above just beyond the lock pliers.  Just pull the bakelite out.

[KCMike]

  I like that idea. Have to try it next time I encounter those type of cans.

[klondike98]

Used a couple of 6.8uF Solen caps to replace the original 6uF.  Here's a pic of the new cap ready to get stuffed back in the can.  Solen's are not electrolytic so there is no polarity.  One side is threaded around the bolt head with a washer and nut tightened down and the other end (what would be the negative side) is a wire that goes through the bakelite and forms a ring around the base of the cap.  This will be what makes contact with either the chassis or the connector that is insulated from the chassis and goes to the B- transfromer center tap.  Russ had a way of connecting the negative lead to the can so its more original but I thought I'd give this a try.  Its still not visible when its all assembled.

[Image: https://www.dropbox.com/s/8z9sf14ubm2r41....jpg?raw=1]

Some epoxy around the edge of the bakelite and then put back into the can...ready for installation when I get to that point down the road.

[Image: https://www.dropbox.com/s/nbb166o5rdugpa....jpg?raw=1]

[KCMike]

 Nice job. Definitely going to use that method next time.

[klondike98]

Next up was the capacitor can (#15 on the schematic) which contains 5 caps.  At first I was puzzled since I could only find 4 leads coming out of the can.  After tracing them out I realized that the paper cap that was on Bakelite block cap #16, and which I had assumed was simply a repair for a bad #16, was actually the 0.1uF (#5 lead) on the #15 can....     Here's the tacked on paper cap and if you look real close you can see the stub of the lead that was cut off from the #15 can.

[Image: https://www.dropbox.com/s/946qxdbkzul118....jpg?raw=1][Image: https://www.dropbox.com/s/aaxyym9mbqok3v....jpg?raw=1]

There's another old rewiring repair job in the set .... but that's for later.

The actual can stuffing was very straight forward.  The surface rust on the can was removed by soaking in Metal Rescue for a few hours, rinsing and drying.  

[Image: https://www.dropbox.com/s/7crdn8uukiac2o....jpg?raw=1]
[Image: https://www.dropbox.com/s/vhzoesm686wjhd....jpg?raw=1]
[Image: https://www.dropbox.com/s/02m0y4wlow9pvo....jpg?raw=1]