Posts: 15,691
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
Well, I gave it a shot.
I opened it up, cleaned it (with alcohol - Varsol seems to be not readily available), used some DeoxIT Greenlabel (Fader Lube) on it.
Where it was the low volume sector, there was bad-bad-bad scratching and the volume would go up (I figured - bald spot), so after cleaning this remained unchanged. I can't have low volume on this thing. After opening, the element did show a large etched bald spot, so obviously through some weird pattern the wiper connects back to a higher resistance part of the scale, increasing the volume, and then, after some really bad scratchy zone, goes almost to zero.
Don't think much can be done.
So, anyone know off hand a replacement part that would mechanically be a good fit? It's a 20K potmeter (don't know linear or logarithmic), with SPST rotary switch.
I looked in Mouser, doesn't look like they have what would fit.
Posts: 289
Threads: 40
Joined: Oct 2011
City: Las Vegas, NV
You do have a good ground on the radio, right? My jr does the same thing if the ground wire isn't hooked up.
John
Las Vegas, NV USA
Posts: 15,691
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
Do you mean if I have the Chassis actually connected to the Earth GND, or do you mean a good connection of the Volume pot to the GND?
The latter I do.
The former I don't.
But the same exact principle (the pot dividing Antenna directly) applies across many Philcos, in my 20 in particular, and it works just fine, and I don't see why not. The divider is there.
Posts: 15,691
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
Just hooked the GND wire to GND in my outlet. Same thing, nothing's changed.
Well, I just paid a bit more attention. With or without GND connected there is a change in volume.
The problem is that where it would be an acceptable volume level while listening to the loudest station, this is where that bald spot is.
So the volume stays very loud, and then goes to almost nothing. But it does change.
I have to tune out a bit, and thus make the station less loud, and then the volume regulation works better.
But...still a new regulator would be better.
(This post was last modified: 04-09-2012, 09:31 PM by morzh.)
Posts: 7,283
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
Two thoughts come to mind. Try rubbing some pencil lead in the bad area of the control. This may restore the resistive path around the control. Or wire it backwards. As soon as you turn it on turn it all the way up and then turn in down to increase the volume. Works but is a little counter intuitive.
Terry
Posts: 15,691
Threads: 551
Joined: Oct 2011
City: Jackson, NJ
Terry,
The last suggestion (wire backwards) was my knee-jerk reaction.
Two cons: 1) the way pot is soldered to the chassis is through a riveted GND contact; wiring backward will be awkward. 2) Exactly what you said - counter-intuitive.
As for rubbing a pencil lead, it is an old technique of fixing potmeters, which I used in my young years (long time ago), but it did not last long enough. If there only were some simple process of graphite application the way they do it at the factory. How do they do it? So it actually bonds?
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
Jackson 715 not working
|
Now that you posted the schematic, I don't know why that Sprague electrolytic cap is across the meter, as it is not indi...MrFixr55 — 05:51 PM |
HiFi (Chifi) tube amp build - but my own design.
|
What may be lacking in the PP Tube amps may be the 2nd harmonics, which some, especially RCA back in the day called &quo...MrFixr55 — 05:32 PM |
Jackson 715 not working
|
Usually in an emission tester, the tube under test is measured as if it were a diode. So, some testers connect all the g...RodB — 04:17 PM |
Restoring Philco 37-604C
|
Yep. F5 is green, D5 is Red.
Red is Bad.
Green is Clean.morzh — 01:30 PM |
Jackson 715 not working
|
I did start to do that but I stalled out because I could not figure out how the grid and plate get voltage. In this diag...daveone23 — 11:52 AM |
Restoring Philco 37-604C
|
(Insert Homer Simpson "DOPF" Here.)
When all fails, look at the can. Took the Ron Ramirez advice, red Caig D...MrFixr55 — 09:23 AM |
Philco 91 Speaker Replacement
|
From your text I am not sure if you intend to use the existing speaker with a resistor instead of the field coil.
It wo...morzh — 08:44 AM |
Philco 91 Speaker Replacement
|
My field coil is bad. I am still hoping to find an original, but if I can't I will go with a fitting Philco speaker, 125...dconant — 08:34 AM |
Philco 91 Speaker Replacement
|
As Rod said, it is OK to use a fitting speaker, and then look for an original one.
If you buy a Hammond 125 output tr...morzh — 08:15 AM |
Philco 91 Speaker Replacement
|
Yes, I often have to substitute, then keep an eye out for an original. In the meantime, the radio is working and being e...RodB — 08:02 AM |
Who's Online
|
There are currently no members online. |
|
|