Time for another update. I got the band switch reassembled after freeing it up. I had to push the shaft back in partially, and that allowed me to still rotate it around while popping the contact springs back on the tabs. Once I figured it out, it went pretty quick, and I was able to button up that part.
Next was replacing cap 22, which was bakelite block 4989Z. It had been removed, and a couple black bumblebees put in its place. I bought one from a friend, and re-stuffed it.
Next up was the dual electrolytic, cap 62-63. It had also been replaced at some point with a triple cap can. I gutted it, and put the new 10ufd, 450v ones inside.
Can anyone confirm if the correction I made to the schematic is in fact correct?
My 1st power up is in the following video. There is a loud hum. I'm still investigating the source, and I'm wondering if it has to do with the correction I made, or if it's another problem altogether.
Yes, it is correct. Without that dot where you drew your red circle, the 75 tube would be receiving plate voltage, but the plates of the other tubes would all read 0 volts. And there would be 0 volts on the screen grid of the 42 output tube as well.
That is a junction point for the B+ line of the set, which distributes high voltage to all four tubes in the set (I am not counting the rectifier, obviously). If you study the schematic carefully, you will see this clearly.
(08-04-2016, 07:08 PM)Ron Ramirez Wrote: [ -> ]Yes, it is correct. Without that dot where you drew your red circle, the 75 tube would be receiving plate voltage, but the plates of the other tubes would all read 0 volts.
Thanks for the confirmation, Ron. Much appreciated. I'll keep looking.
Well, I did some investigating. I thought the problem was either in the audio section, or the main filter dual capacitor. It turned out to be the dual neg common from the filter cap. The solid wire was broken inside the insulation. I just didn't see it or notice it while going over everything.
(A pic is included in the following video.) New replacement wire is now in, and she sprang to life.
While uploading this to YouTube, I performed an alignment by ear, and both bands are performing nice and strong.
All buttoned up and back in its home cabinet.
It's been running well for over an hour now. I took the grill cloths out, carefully pulled them off the backing boards, and soaked them in the sink with hot water and Woolite. Didn't completely get them clean, but it brought the shine back to the gold in the cloth. Re-mounted them using 3M 77 adhesive spray, and reinstalled.
I'll post a video soon.
Thanks for following along, and the comments.
Sorry Jerry Hawthorne, this is in my permanent collection. Better luck next time.
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Jeff, a lovely radio and I'm glad that it back and singing. Congrats on your hard work. As far as I'm concerned the nicest style Philco table top made and looks great setting there around period stuff. Great job.
Here's a short video of it all back together and working.
Very nice job Jeff and vintage music as well.
Jerry
Here's a quick update to this thread. I bought some grill cloth for another Philco, and decided to put new cloth in this one. What a difference it made in the appearance!
Here's an updated "studio shot" of the "butterfly".