[KatRadio]

Hello, I am new to the site, but I remember seeing some posts about the two radios that I am currently (trying) to restore. I have had the 125 for years, and finally dug it out of storage. It didn't power up, and somebody had chopped the wires on the speaker. The 120 I found at a bargain store had a AC hum. Easy i thought, filter caps, when I opened it up, what a mess!! My question is about the molded mica caps, and the color code not matching what is on the schematic. Like I said,  I had seen something on here about that.
I figure since the 120 had the hum, and the wiring has all of the old insulation flaking off, it wasn't gonna work anyway,so it's a learning experience. The 125 wiring is in the same state.
I spent a couple of days drawing out a wiring diagram for the 120, showing the locations of all of the snakes nest of wiring, and the caps and resistors, this being easier to follow than the schematic.
I had to replace the leads on the 2nd IF can, and RF transformer coil,  which I had a really bad time getting one of the fine coil wires back to where it should be. Checking the connections, and going by what I saw on YouTube University, the resistance matches what the guy on the video had. The oscillator coil is next up to rewire.
If there is something I need to look out for while I doing these restorations I would really appreciate any help.
Thanks!

[morzh]

Welcome!

Now, your first mistake was powering the radio up.

Rule #1 of teh radio restoration: do not power an unknown radio up. You do not know if thera shorted wires, shorted tubes, shorted capacitors. You are in fact lucky it did ot go up in flames.
Restoration takes patience and time.
Otherwise any 5-year-old would be able to fo it.

Rile #2 (well, I am improvising here, but I kinda followed it when I started. And I am pro EE). Having no experience, find he / a forum that has people who do that stuff and ask.
Then some one would at least give you this link

https://www.nostalgiaair.org/pdfs/Philco...40-120.pdf

and you would kill two cats with one dawg: 1) you would not have to spend a couple of days drawing the diagram, and 2) you would become aware of what Riders / Nostalgiaair.org is. They will have most of the schematics you will ever need.

Now. I would strongly advise to not powering this radio up until you

- Check the power transformer. For this, remove all tubes, disconnect bad wiring, and make sure your transformer works.
- Rewire. All bad wiring has to go. Some advice: don't remove wiring and then use the circuit diagram, which could have mistakes. Remove wires one by one, replacing as you go.
- Recap. All capacitors other than mica and trimmers/padders have to go. Whether you decide to replace or restuff - up to you, but do not proceed until done with the full recap.
- Check all resistors, replace thos that are close or outside 20% of the declared value.
- Check all tubes, preferably not just for emissions. Also for shorts. And, if possible - for mutual conductance.
- Replace the cord.
- Check for shorts at the power supply before installing the tubes.

Once done with all this, you could start powering up. Some people use dim bulb, I am a staunch opponent of this and recommend Variacs.

[klondike98]

Welcome to the Phorum!


Our digital library also has those schematics and are usually a little sharper than the one on nostslgiaair.
https://philcoradio.com/library/download...20Book.pdf

Here is an article from the library on the rubber wire insulation problem you are seeing:

https://philcoradio.com/library/index.ph...2-philcos/


The mica caps usually do not need replacing while all the tubular paper caps and electrolytic filter caps do.

Most folks find it helpful to take photos during the restore to help you remember how things go back together. To the extent possible, replace one component at a time to avoid miswiring something, although you often need to remove several components at a time simply for access to a spot.