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38-3 Dial question - Printable Version

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+--- Thread: 38-3 Dial question (/showthread.php?tid=976)


38-3 Dial question - gary rabbitt - 02-18-2008

Hi guys,
I rcently bought a 38-3. The dial scale had broke at the point where it attaches to the inner ring of plastic. That is repaired now.
I make a detalied set of notes and assembeled the dial assembly back.

My question is, did the dial touch the place shown on the photo? As I didn;t see it originally, I don't know if it should be in the center of that part, or if felt was added to guide the dial through.

As it is, the part ( it is the auto tuning selector) had felt, but is rotting away. Maybe the dial touched the area shown and the felt was gone. Leaving it as is, the dial woluld get srcaped by the metal. WOuld felt wear off the paint on the dial?

So, should dial be centered in that space?
By the way the selector is in the exact spot where it came off of the shaft.
Thanks!
[Image: http://aycu04.webshots.com/image/46083/2005672917348562774_rs.jpg]

[Image: http://aycu19.webshots.com/image/44418/2005670365559537670_rs.jpg]

- Ron Ramirez - 02-18-2008

Hi Gary

Very interesting...I have never seen one of those parts that HAD felt on it! Only bare pot metal.

The dial scale should be centered in that space; if it rubs on bare pot metal, then yes, it will damage the dial scale sooner or later. But I would think that felt would protect the dial scale to some degree?

- gary rabbitt - 02-18-2008

Hi Ron, thanks,

I may try to see if I can move the selector outboard just a bit, but that would not be where it was originally. I can see where the set screw was.
The rest of the dial assembly is where it should be and there was no other way to make the dial move inboard.

The felt would protect the dial but over time I think it would wear off the markings, and we don't want that Icon_smile
I will have another look and see what I can do.
Take care my friend,
Gary.

- BDM - 02-19-2008

If I remember correctly, you can move the spool that the dial mounts on. You loosen that screw for dial scale calibration, and you should be able to move it in or out as needed.

- gary rabbitt - 02-19-2008

Hi,
I will have a look and see where that is. I tried to not move anything and mark it all when I took it off.

All it needs is a 1/8" clearance.
Last night I rotated the dial and it only touched slightly. I installed a thin piece of flannel (felt was too thick) on both sides, just in case it touched again. I may be good to go.
I'll have a look at that adjustment later on today. Going to test the trans today , I think it may be ok. Then, on to the recap (restuff of course Icon_smile)


Take care,
Gary.

- planigan - 02-20-2008

grayrabbit, the dial scale may be warped. See if you can put one of the self adhesive felt dots in a place where it will not wipe over the printing, blank area. That should hold it away from fitting but not wear off printing.
PL

- gary rabbitt - 02-21-2008

Hi Planigan,

Thanks for the tip, I didn't think of using the dots.
I did use a piece of thin flannel. Regular felt was too thick.
You're right, the dial was slightly warped, and as I tuned, it would move to the center and back. I think there was not that much pressure, so now, the felt will protect it.

The original stuff looked like the flocking on turntables.

Now that probem is solved, I am on to the recap.

New issue, the on off/Tone switch (4 position ) is broken. The wafer that makes the contact to select the tone is missing, including the ball bearing.

I have found a NOS Mallory switch that attaches to the bottom of the selector. I am halfway there Icon_smile

I am in contact with Mark Oppat, he might have a broken one I can repair. The switch is no problem, but the 4 position switch is what I need. It would be almost impossible to recreate one.

I think the replacement was a Centralab 1465, which is no doubt obsolete.
I'll work on the recap, while trying to locate the switch.
I realy don't want to add in a modern switch , that would be a last resort.

[Image: http://aycu11.webshots.com/image/45770/2005936197095870675_fs.jpg]

[Image: http://aycu16.webshots.com/image/45775/2005901644171305338_fs.jpg]

Take care,
Gary.

- planigan - 02-21-2008

grayrabbit, are you sure that switch is missing a wafer? I see the wafer with the three terminals. Do you mean the rotating contact disk is missing?
If you can feel three positions click in when you rotate it, it should work.
When you say four position I take it that one position is off, second on, third one tone position and fourth second tone position. The wafer switch would really be a spdt switch. As you turn from off to on the wafer would turn but make no contact, next turn would make first contact on wafer and next turn would make second contact. I have not seen schematic but would guess switch places one cap in a curcuit and then either adds second cap or disconnects first and supstitutes second. Did you check for continuity between the three terminals on wafer? Wafer will not be electrically connected to on/off. Only physical connection of rotors on shaft between them. If you get continuity between one terminal and then one or both of the other terminals switch is OK. If ball bearing missing
(which gives switch the "click" and locking effect) you may be able to replce that. They are usually held in by tension of metal wiper. PL

- gary rabbitt - 02-22-2008

Hi Planagan,
Thanks for getting me to think. I guess when I meant wafer, it was the rotatable contact that is missing. Or so I thought.

Your post made me think though. The diagram shows the switch connected to ground, and NOW, I see that there is a small tab on the shaft that will pass through those contacts. Yes! (See pic)

So, I think that the switch would do it's switching task.
(I think the worst is over. Icon_smile

Two problems remain. The actuator on the AC switch, one is indeed broke off. I can manually turn it to ON, and the shaft will rotate to trun it off.

1. I have a NOS switch assembly I will un-rivet and add back.

2. The spring tab that held the ball bearing in. I can see where it had broken off the shaft. (See pic) So I need to create the spring device to hold the BB in. I have some old switches, so I can either rob one, or make another from scratch.

I will have to disassemble the switch anyway to add the AC switch on, then remove the shaft, then add in the ball bearing retainer. It may an hour or two if all goes well. I hope that I can take off the stack of a contact and the spring, (off the shaft) and get it back together.

The stack might be pressed on, or maybe held in by the shaft retaining ring. The Rabbitt will find a way..

Will let you know how the surgery goes, I am up to the challenge so to speak.
Take care my friend,
Gary.
[Image: http://aycu17.webshots.com/image/46496/2004545271702064043_rs.jpg]

[Image: http://aycu11.webshots.com/image/45290/2004576474211993887_rs.jpg]

- planigan - 02-22-2008

Gary, thats some project your taking on. Your worse problem is the broken spring type part that held the bb in. Also it looks like that assembly is rivited together. If you can't find a replacement for the spring type piece you could still operate that switch but no "click to let you know when your in each position othere than the on/off "click". I'd recommend that you try to locate a used switch. If you can not locate a new switch you might be able to duplicate it with a two wafer switch. By wiring some terminals together and wiring from one wafer to the other it can function the same. The only draw back is the on/off switch. Wafer switch may not handle power and it would not make/break as quickly which would tend to let it arc. Which ever way you decide, good luck with it. PL

- gary rabbitt - 02-22-2008

Hey there Planigan.
Un-riveting is no problem at least for me Icon_smile I can use a thin bo;t/nut to reassemble.

I have taken apart the unit, and fitted the NOS AC switch. It works correctly.
Now, ad you can see the spring steel BB retainer is the problem.
I was hoping that the "stack" of items on the shaft would come apart. But they are pressed on the shaft.

I will see if Mark Oppat has at least the shaft with the spring on it, that wouldd save me some time.

But if not, I will indeed disassemble that shaft's elements then ( I have already marked them) install in their original position, and tap down the smashed part on the shaft, thus holding the elements back on the shaft.

I have got some spring steel shim material that I can make a retainer with.

Planigan, I am the kind that if I can see something can be saved, I'll try it. But I am hoping Mark will have a shaft from a broken switch.

PTOP has a NOS Centralab switch that has the AC option, so that would be a last resort.
Will let y'all know how it comes out.
Take care,
Gary.

[Image: http://aycu38.webshots.com/image/44477/2005513355422358610_rs.jpg]

[Image: http://aycu39.webshots.com/image/44598/2005524626293770652_rs.jpg]


[Image: http://aycu38.webshots.com/image/44477/2005579552769063570_rs.jpg]