[jerryhawthorne]

Have the radio working well but still a couple of problems. Let's start and focus on the first. The problem is that the muting switch well, doesn't seem to mute when pressing in on the new yoke assembly I recently received. I'm posting a picture of the old one without the yoke, exactly like the new one I put in. I'm making an assumption and you know what that means. As one presses in the speed dial and engages one of the preset screws part of the yoke assembly appears to also press in to the brass clip you see in the picture and if all works well, that clip presses into a connector tab on the yoke assembly that is connected to the yoke, and "grounds" it. Seeing how the nice spring piece is also connected to the shaft, how the hay does it do anything? It doesn't. Am I missing some isolating piece somewhere?
Anyone shed some light how this is supposed to work?
Jerry

[Image: http://i303.photobucket.com/albums/nn129...switch.jpg]

[jerryhawthorne]

Seems the posting is not generating much interest so I started thinking about it more. Could this just be a spring system to allow the speed dial lever to lift up? The station stop screws are very spring loaded which will lift the speed dial lever but perhaps this is to get it a little higher so it is assured of not dragging. Maybe I'm chasing a red herring here and the muting switch is somewhere else in the dial assembly? The schematic shows what I think is the muting switch and looks like it grounds out the center tap of the volume control. This doesn't appear to be able to do that. Is it possible that the switch is located under the back of the dial at the bottom where I can see two wires coming to what appears to be two leafs wanting to touch one another? I may have to look more closely at that. I did jumper across the two connections and no muting. May have to look at that closer. No idea what it does but if it is a muting switch, according to the schematic, one side should go to CT of the volume control and the other leg to the ground. Any experts out there?

Jerry

[Phlogiston]

Jerry,I was pretending that I did not see this
So I would not have to answer - there are a bunch of washers and an odd shapped insulator around that part.

Did you find the lever? the insulator sits under it - black, stiff paper with a tab that sticks out just as the lever does. Do you have those parts?

[Ron Ramirez]

Jerry, please, patience is a virtue. It's the weekend and a lot of us, myself included, are busy. And I have to work tomorrrow.

Anyway...

You are correct, the metal "ring" with the long tab as shown in your photo is part of the radio's muting mechanism. Normally there is another fiber insulator on top of the ring, with a very small tab which only covers the part of the metal tab closest to the ring part of the piece. Just as Phlogiston described, and I think he did a better job of describing it than I did. Without this insulator, the set will stay muted all of the time.

If it isn't muting, then something is keeping it from muting. Maybe some dirt or a foreign object keeping the muting circuit from grounding properly? Maybe it isn't connected properly? Just some random thoughts.

[jerryhawthorne]

Thanks Phlog and Ron. Sorry for being in a hurry, patience was never my long suit! Yes, with the new assembly I received from a phorum member I did receive a couple black "washers" with tabs that wanted to fit around the spring clip. I didn't realize they were fiber. Also I found a "ring" of insulating material that could isolate that spring tab from the shaft. I can disassemble the part and put it back in such that I think the spring part will not go to ground without being pressed down to contact the the rotating part with the yoke. I still don't see how that will mute the radio when it appears the switch should take the volume control center tap (if I read the schematic part properly) and short it to ground. How does that line get to the spring clip? Even now all seems to be grounded to the shaft and the radio is not in a mute mode.
Sorry, just confused in Arizona.

Thanks for the help. Jerry

PS: Phlog, I have not heard back yet on the process of making a few tube shield assemblies for the 111 and 112. Will let you know when I get my one back I sent for a "model".

[jerryhawthorne]

I thought I would add a little more food for thought. Attached is the schematic and what I think is the mute switch is item 86, from the CT of the volume control to ground. I could be wrong and often are. If it is true I don't see how the that springy thing is going to do it without some wire going to it attached to the CT of the volume control.
Jerry

http://www.nostalgiaair.org/PagesByModel...013235.pdf

[jerryhawthorne]

Well it is muting! I had the insulating washer on both sides of the spring clip. Took one off of the back so the clip would not be insulated on that side and I'll be darn, it's working. Now how it is working I'm clueless. I cannot see how that ring being shorted to ground is in anyway connected to shorting out the audio on the radio. Now call me curious, but it works!
On to the magnetic tuning and a little research on why it doesn't do what I think it should. We are muting!

Jerry

[Phlogiston]

The tuning shaft has a conductor, isolated from the shaft attatched to those 2 wires behind the dial on the right - - I think.

[jerryhawthorne]

I'll be dang Phlog, you are correct. I was wondering what those two wires going to perhaps some wiper to a insulated ring around the shaft. Put in the insulators in the proper position and it will now mute! On to the mag tuning issues and home free.
Jerry

[jerryhawthorne]

Now that we solved with a lot of help the question of muting, time to move on to the next question. First, remember I'm rather dumb about electronics but have figured out the usual stuff. I will post a link to the schematic of the 38-116. The one I have works quite nicely. The mag tuning does not work. Tubes test "fair" at least not shorted or dead. Transformer tests good for the mag tuner circuit. Problem is going through the alignment of it, neither the 53B or 53A alignment caps do anything! They will not change the 100KC signal although it runs through to the speaker nicely. Just no adjustment.
By the way, the cap in that dang RF unit I can't reach is the .05 listed as #7 on the schematic, in the antenna area. I suspect it doesn't see much voltage. I may leave it alone unless Ron holds his class on taking out the RF deck.

Can anyone out there suggest a trouble shooting sequence? I have a scope, generator, VOM and digital DVM. I just do not know how it is suppose to work. An explanation of that would help.
Jerry

http://www.nostalgiaair.org/PagesByModel...013235.pdf

[Phlogiston]

Pay attention to step G - "MINIMUM output".

And I tell you what, it seems to work good sometimes and not make much difference other times. If you turn Mag tuning on and have to move the dial to get a better signal from a station you already had set - you got it wrong.

[jerryhawthorne]

Thanks Phlog, adjusting per step g does not change the output of the radio at all. Seems to just blast through well. Perhaps you need a vacation to AZ? Can't seem to get Ron out here.

Jerry

[Phlogiston]

I would do it for you. We did get down there last spring. No way to tell yet this year.

If you follow the alignment steps carefully it should work. Don't inject too much signal.

[jerryhawthorne]

Well, kept my sig generator as low as possible and injected a 100KC signal with modulation into the antenna lug and "g" does nothing to the output (tone level sound) out of the speaker which is strong at max volume.
Not understanding how a signal (a tone AF) which I believe is going into that section is going to somehow alter the tuning of the radio I'm a bit stumped. A brief explanation of how it works would be helpful for troubleshooting it. I will check tube voltages tonight but would be nice to also use my scope to look at what is happening. I just don't know what is suppose to happen. There must be some feedback from the mag tuner to something. I just don't know what to look for. Any help please? I need a rough theory of operation of the circuit focused for the dummies.

Jerry

[jerryhawthorne]

I know all of you are looking so I thought I would add a little bit more. I set the 6j5 tubes, one at a time on my extender. This chassis is nasty to turn over! There is no plate voltage on either of them. Doesn't make any difference where the mag switch is turned. No listing what it should be but I suspect not Zero. Need help!

Jerry