[numberdevil]

Greetings!

I am starting my first restoration project with a philco 39-7. I am going to replace the electrolytic capacitors, the paper/wax capacitors, and the power cord (It's toast). I will also be checking/replacing the resistors, and any wiring that looks bad.

My first question is how to replace the electrolytic capacitors. I would like to remove the can, but was unable to do so. Plan B is to replace the cap, but put the cap under chassis. The electrolytic has one terminal that extends under the chassis. How do I replace that with one that has the two leads?

Thanks in advance for your replies!

[Dave]

- lead should be attached to the chassis and the + lead should connect in place of the can terminal under the chassis. DO NOT connect the new capacitor to the terminal of the old capacitor.
Dave

[numberdevil]

Thanks, Dave! That helps a lot.

I did not remove the old cap, but I will NOT connect the new one to the old terminal.

As far as connecting the neg to the chassis, does it matter where? Could I attach it to the nut on the old cap?

Nicole

[DKinYORKpa]

I have frequently used this idea gleaned from another forum: solder a terminal strip mounting lug (w/o it having a solder lug on it) to the electrolytic terminal. Then all of the wires that went to the electrolytic will usually reach the new electrolytic mounted to that terminal strip. Getting creative with new filter caps (when not restuffing the cans) is always fun!

[numberdevil]

Thanks, DKinYORKpa.

I think I will try your method.

I wanted to restuff the cap, but I can't seem to remove the old one without risking damage.

[Radioroslyn]

Hi Nicole and welcome to the Phourm!!!

- lead should be attached to the chassis and the + lead should connect in place of the can terminal under the chassis. DO NOT connect the new capacitor to the terminal of the old capacitor.
Dave

Not necessarily so. Depends on which filter cap. If you look at the diagram http://www.nostalgiaair.org/PagesByModel...013301.pdf you'll see that the negative side of #25 does, but #26 DOESN'T. It goes back to the center tap on the HV winding of the power transformer. If you connect #26 to the chassis it will hum alot. There won't be any filtering for the grid bias on the 41 tube.
Terry

[numberdevil]

Thanks, Terry!

Yes, you are correct. One of the electrolytics is ground to the chassis, and the other does not. Thank you for reinforcing that for me, AND telling me what would happen if #26 was grounded.

Hoping to get started this weekend. Definitely will be posting more questions, I am sure.

Nicole

[ipwizard]

Pictures too. They help us see what your seeing..

[numberdevil]

Yes, Pictures! I know I need them.

Here is what I am looking at now.

[Image: http://i326.photobucket.com/albums/k432/...011029.jpg]

What I have determined so far is that the transformer has been replaced, and so has the rectifier tube. The 84 has been replaced with an 80 and resulting rewiring ... no evidence of anything burning up so my thought was to replace the paper and electrolytic caps, check/replace resistors, and resleeve wiring that is crumbling, and see what happens.

I have a question regarding grounding the neg on #25. there is a two lug terminal strip. on one lug, the .006 mf cap and the line is grounded, and nothing on the other. Can I attach #25 to the lug that has nothing?

[Image: http://i326.photobucket.com/albums/k432/...1029-2.jpg]

[Radioroslyn]

Yes.
Terry

[numberdevil]

Thanks, Terry.

I have replaced that cap, and am getting ready to replace the other electrolytic. I have some terribly crumbling wire that needs to be replaced/resleeved. I have resleeved a couple of them, and was wondering about replacing the whole wire. The wires I have resleeved are sold, and very thin. What is the appropriate wire to use as a replacement?

[Radioroslyn]

The wire isn't very critical something like 22 gauge and the insulation should be good for 200v or better. What I do sometimes is use the wire from an old computer power supply but I'm CHEAP. A friend repairs computers and he saves the power supplies for me. Along with the wire there are lots of little goodies on the circuit board. Diodes,bridge rectifier, and caps to name a few. It's not a bad thing if you can replace the bad wire with one that's the same color. Won't make it play any better but may make it easier to fix.
Terry

[numberdevil]

Does it matter if a solid wire is replaced with braided wire? I haven't done so, but was curious. Just in case I mess a wire up resleeving it.

Getting closer for a test. Have to replace the power cord next, then should be ready to test. I am sure I will be asking questions about that when I get there.

Thanks for the replies!

[Radioroslyn]

I think what mean to say is stranded or solid wire. Braided usually refers to the outside of the wire like shielded wire. Not picking on you but just want to use the proper terms. No the radio doesn't care.
Terry

[numberdevil]

thanks, Terry.

I did mean stranded. I had just been talking with someone about a fuel line for my bug ...