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STRANGE

Post by denver on Mon Apr 26, 2010 10:30 pm

Answer me this . My set will pickup good turn off wont . Decided to check plate voltage on oscillator good 65 volts.
Was checking other voltages touched where plate of oscillator goes to osc coil started working .
Have to do this almost every time i turn it off and back on. What would cause this just by touching this wire set works.? Rolling Eyes Mad OH philco model 111.
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Re: STRANGE

Post by Resistance is Futile on Tue Apr 27, 2010 8:17 pm

My set will pickup good
You mean that this radio works well?
---------------------------
turn off wont
You mean you can't turn the radio off?
------------------------------------

plate voltage on oscillator good 65 volts.
Should read
osc filament volts= 2.1

plate-volts = 45
control grid = .7
cathode volts = 7
-----------------
to much feedback in oscillator due to higher voltage???, start checking resistors for value change. If caps are failing they would allow AC freq to either short to ground or be open and bandpass frequencies not be filtered.
Not much experience here with this. It sounds like you are upsetting the voltage by touching and may be due to capacitance or frequency change as it is unstable tank circuit. Could be the tube? Suspect
And of course check wires for bad connections.
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Re: STRANGE

Post by sprman on Tue Apr 27, 2010 8:46 pm

Check the resistors and replace any caps that have not been replaced.Get the voltages where they need to be,try a diffrent osc tube..Sprman : )

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Re: STRANGE

Post by denver on Tue Apr 27, 2010 8:59 pm

I was tired when i typed the post. Wink Everything checks out okay resisters ,ect . I mentioned this once in another post .
The micas from osc to osc coil should i replace theses ? The only caps i did not replace in the set . What do you think. Reason i asked was checking voltages on other parts touched where the micas are wired from osc to osc coil started working. Have to repeat this when i turn it on . Rolling Eyes . Thanks Denver. Very Happy
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Re: STRANGE

Post by Resistance is Futile on Wed Apr 28, 2010 6:54 pm

Well the Variable Micas can have silver migration and make for a ghost electrical path. Remove, disassemble, dip into silver cleaner, rinse well in distilled water, dip in Isopropyl Alcohol to remove moisture, reassemble, connect and see if that makes a difference.


Last edited by Resistance is Futile on Tue Aug 10, 2010 2:38 pm; edited 1 time in total
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Re: STRANGE

Post by sprman on Wed Apr 28, 2010 8:37 pm

Now theres a tip i remember..Wonder if it does help to do that...Thanks..Sprman : )

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strange

Post by denver on Wed Apr 28, 2010 9:27 pm

Sorry . But the mica caps iam talking about are hearhttp://www.philcorepairbench.com/micacap.htm
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Re: STRANGE

Post by GaryRabbitt on Tue Aug 10, 2010 1:31 pm

I remember a video on Youtube from Allamericanfiveradio that shows the same problem..
He just touches a wire in the right spot, and the radio will play fine from then on.

Supposedly, it gets the oscillator working.

Permanent fix was to replace a cap. Could have been a mica.

EDIT>>> OK I found the link to the video. This is probably what you are dealing with.


I have had that happen to me too and a mica cap was to blame..
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Re: STRANGE

Post by Resistance is Futile on Tue Aug 10, 2010 2:35 pm

Very good demo!
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Re: STRANGE

Post by GaryRabbitt on Tue Aug 10, 2010 2:47 pm

Hi,
Yep, Rick has a lot of great videos. Ranging from cabinet refinish, to mechanical repair, scope work, all kinds of electronic goodies.

This type of problem plagues me once in a while. I don't have reception, then probing around I accidently spark something ans the set begins to play. Usually in the osc circuit.
Hope the OP can find exactly what cap(s) need to be replaced.
Take care,
Gary.
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Re: STRANGE

Post by denver on Tue Aug 10, 2010 7:03 pm

That is what i found out . a mica off the osc circuit. Just touch it it will spark and work . Strange indeed.
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Re: STRANGE

Post by Resistance is Futile on Wed Aug 11, 2010 2:03 pm

Ok start looking at bad solder connections. The Video mentions this (even though they look good).
could be the wire underneath the solder is oxidized, or a hairline crack between the wire and solder from repeated heating and cooling, or a cold solder joint. Also a wire or resistor or cap that appears good but isn't making good electrical connection Ive seen this happen to where the wire looks solid but in fact just butts up to the case of the passive component. Also check all electromechanical connections too. Use an ohmeter to check continuity from each and every wire.
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Re: STRANGE

Post by denver on Wed Aug 11, 2010 6:56 pm

I watched the video very interesting. Wink
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Re: STRANGE

Post by GaryRabbitt on Thu Aug 12, 2010 12:07 pm

I think more often than not, it is internal in the cap.

Of course the basics like solder joints should always be checked, prodded, pressured, and the old "wiggle test" Smile

In the video, he ended up replacing parts in the osc section. He might not have needed to replace all those parts, but he did anyway.
You might want to carefully replace a mica cap in that section. If no change, do another. When replacing micas, part value is important, and the leads should be exactl where the old leads went. (Lead dress.)
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Re: STRANGE

Post by denver on Tue Nov 16, 2010 10:00 pm

Ok . Finally got back too this set. A mica cap in the oscillator circuit was leaking. When i ordered caps for another set . Got one close too original value of mica cap
piggy backed it across the mica, Works like a new set now.
Before had to just touch the mica cap radio would work awhile then quit. Strange watch the video in this posting.
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Re: STRANGE

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