08-30-2013, 02:18 PM
Got a variac and a schematic and got into the guts of this yesterday. Three immediate problems:
1. Volume knob was scratchy. Needed disassembly to clean with DeOxit, that worked, but the power switch never worked again. I did get a modern replacement that went in fine.
2. The 0.01uf wax cap on the volume control fell off. This was replaced with a modern cap, all I had on hand was a mylar capacitor, should this be replaced with an electrolytic, or will this be fine?
3. A wire was dangling off of the I.F. trans assembly. After sweating over the schematic, I found its old location and reconnected it.
All else looked good, except one green wire started flaking off insultation material. Since I had it off anyway fixing the volume, I sealed it in shrink tubing.
The person who had this before me cleaned up the case real nice. They also replaced all the caps on the power side. There's still 3-4 wax caps in it that I need to get to.
I did bring it up on the variac slowly with no signs of a problem. At approx 80VAC the speaker started making static, a bit higher and a station was coming in loud and clear! It's not smoking either!
So I reassembled it and looked it over - it tunes great, sounds great except for some slight hum/buzz that changes with volume. I have it next to its sibling 39-6 I posted about earlier and know I know the speaker in the 39-6 needs to be re-coned.
Next up on this is figuring out what rubber spacers are needed for the pushbutton tuning assembly, swapping out the remaining wax caps. I also need to get a polarized plug and put a fuse on it.
Still, this is my first electrical repair and I'm quite pleased I was able to figure it out myself. After I wrap this one up, I'll tackle something a bit more difficult.
1. Volume knob was scratchy. Needed disassembly to clean with DeOxit, that worked, but the power switch never worked again. I did get a modern replacement that went in fine.
2. The 0.01uf wax cap on the volume control fell off. This was replaced with a modern cap, all I had on hand was a mylar capacitor, should this be replaced with an electrolytic, or will this be fine?
3. A wire was dangling off of the I.F. trans assembly. After sweating over the schematic, I found its old location and reconnected it.
All else looked good, except one green wire started flaking off insultation material. Since I had it off anyway fixing the volume, I sealed it in shrink tubing.
The person who had this before me cleaned up the case real nice. They also replaced all the caps on the power side. There's still 3-4 wax caps in it that I need to get to.
I did bring it up on the variac slowly with no signs of a problem. At approx 80VAC the speaker started making static, a bit higher and a station was coming in loud and clear! It's not smoking either!
So I reassembled it and looked it over - it tunes great, sounds great except for some slight hum/buzz that changes with volume. I have it next to its sibling 39-6 I posted about earlier and know I know the speaker in the 39-6 needs to be re-coned.
Next up on this is figuring out what rubber spacers are needed for the pushbutton tuning assembly, swapping out the remaining wax caps. I also need to get a polarized plug and put a fuse on it.
Still, this is my first electrical repair and I'm quite pleased I was able to figure it out myself. After I wrap this one up, I'll tackle something a bit more difficult.
