Philco 45 tone control caps.
Posts: 15,704
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
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?
Posts: 15,704
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
OK, found my answer here
My values were close
http://philcoradio.com/phorum/showthread.php?tid=729
Good!
(This post was last modified: 06-28-2014, 06:07 PM by morzh.)
Posts: 4,686
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
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
Posts: 15,704
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
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.
Posts: 4,686
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
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
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
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!
--
Ron Ramirez
Ferdinand IN
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
Philco 91 Speaker Replacement
|
The spider is glued on the cone and so is the voice coil. I think you can use a cotton swab dipped in acetone and carefu...RodB — 02:42 PM |
Restoring Philco 37-604C
|
Yes I saw that. If I knew, I'd probably try to arrange for getting it myself. But I have just got one.
Which does not m...morzh — 01:44 PM |
Philco 38-2 Automatic Tuning
|
When you push the lever, you are supposed to rotate the disk to the desired station.
Then the magnetic tuning will acqu...morzh — 01:42 PM |
Philco 38-2 Automatic Tuning
|
I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push...dconant — 12:11 PM |
Philco 91 Speaker Replacement
|
How would I go about removing the spider from the cone?dconant — 12:04 PM |
Philco 38-2 Automatic Tuning
|
Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to...dconant — 10:51 AM |
Does anyone make photofinish replacements?
|
Here’s the link to the DIY photofinish section of our site:
klondike98 — 09:46 AM |
Delco car radio Peko vibrator converstion issues
|
Hi Richard,
Thx for posting the schematic. As I remember as a kid, these were great performers for the time, likely...MrFixr55 — 08:56 AM |
Delco car radio Peko vibrator converstion issues
|
hello mr Fixr,
The Electro Powersupply that I am powering the radio with has a huge choke plus a 10,000ufd electrolyti...radiorich — 10:58 PM |
Delco car radio Peko vibrator converstion issues
|
How about putting a choke in the power supply?
The big cap was likely an attempt to stabilize the DC. Kids who cre...MrFixr55 — 09:19 PM |
Who's Online
|
There are currently no members online. |
|
|