Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Philco 45 tone control caps.
#1

The 45 (butterfly) tone control's caps values are not shown in the BOM.

Typical values for several Philcos are 10nF,10nF and 15nF for three stage ones.
I inclined to think these are the same, 10nF and 15nF.

Another matter, I noticed that when using these values, the first stage takes out most of Hi and then the to others almost don't matter anymore.
Has anyone found optimal values?
#2

OK, found my answer here
My values were close Icon_smile

http://philcoradio.com/phorum/showthread.php?tid=729

Good!
#3

Mike,
I don't know why Philco insisted on using switches for their tone controls, it rather limits your options, in this case three positions but some only have two. The way they work is strange, they typically have three or four caps, one always stays in series, the other two or three are connected in parallel and are shorted out as you rotate the control, or vice versa. The one on my Philco 3118 has the shaft broken off so I have two options, replace with an aftermarket rotary switch and recreate the original hookup, or just junk it and put a proper linear pot in there.
Compare this setup to a Canadian Westinghouse console I have, it has a tone control pot, and a tone control switch. The switch gives you three ranges bass, medium and treble, and the pot allows you to adjust it anywhere in between. Did I mention that this was also a five tube console, shame on you Philco!
Regards
Arran
#4

The way Philco does it is the caps are put in parallel to the primary of the interstage or output transformer, adding the next cap in parallel to the previous one. A bit of a brute force approach, I agree. The pot regulator should be in the grid circuit, not plate.

Anyway, I have rebuilt the regulator. Same thing as in 90 or 111, just no backelite box.
#5

Mike;
That's a very common setup even with a linear pot tone control, which is one of the reasons why you should always replace the cap connected to to the center tap of the pot used in such setups. I've ended up with more then one set where the tone control pot burned up because that cap shorted to ground resulting in the full B+ flowing through it. One was so bad that it even burned up part of the Bakelite the resistive element was mounted to.
In the case of Philco if any of those caps on the tone control were to short it may take out the rectifier tube, field coil, output transformer, and even the power transformer since there isn't even a resistor in series with them. So basically what Philco did in this case is they substituted their three position switch ans caps for what would be the tone correction capacitor in another make of radio. Caps are cheap, inductors are expensive, change the caps.
Regards
Arran
#6

Arrran Wrote:I don't know why Philco insisted on using switches for their tone controls

Marketing, I think. When Philco introduced their (four position) tone control in the 1930 models (June 1930), they made a big deal in their advertising of their "four point tone control...Brilliant...Bright...Mellow...Deep."

Quote:The switch gives you three ranges bass, medium and treble, and the pot allows you to adjust it anywhere in between. Did I mention that this was also a five tube console, shame on you Philco!

Icon_lol

--
Ron Ramirez
Ferdinand IN




Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
HiFi (Chifi) tube amp build - but my own design.
Tim, nice write up and thanks for sharing !! Sincerely Richardradiorich — 02:47 AM
HiFi (Chifi) tube amp build - but my own design.
Well, this was a real "Hum-Dinger" :lol: ! This will be kinda long, but hopefully it will help others having t...TV MAN — 01:55 AM
Shadow Meter Bulb
Phorum members, I am trying to find the bulb # for PHILCO Shadow Meter part number 45-2180 that is from a 37-640 chassis...georgetownjohn — 06:53 PM
Philco 41-608 changer coupler
3D-printing...short of machining, of course. Or molding.morzh — 05:20 PM
Philco 41-608 changer coupler
Thanks, Morzh. That solves the issue of the rubber pieces. Now, I need to find a way to replicate the pot metal piec...alangard — 05:07 PM
12' Philco
If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel. Kareem would have an e...morzh — 01:48 PM
12' Philco
And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM
Hickok AC51 tube tester
I think they have only shown the secondaries of the transformer. Two of them feed the rectifiers' filaments.morzh — 12:58 PM
IF can wire size and Rubber mounts?
Arran If the wire inside cans is the gauges you mentioned, the sole reason for that would be mechanical, to stiffen t...morzh — 12:56 PM
12' Philco
Rod, Yes, I know, but the Giant Philco is not around anymore either, so I go by whoever was alive fairly recently. H...morzh — 12:54 PM

[-]
Who's Online
There are currently no members online.

>