Transmitter Capsule Disassembly and Refilling

[rp2813]

I did some searching and found a few posts that reported success with bad transmitter capsules being refilled with carbon granules.  I presume there are specialized tools suited to this process, but in my reading I didn't see any references to the type of tools that were used.

I bought a 9/37 F1 capsule on eBay recently (no subsequent dates on it) and it was bad.  No noise when I shook it, no amount of rapping/tapping loosened things up, and when I tried it out, I got complete silence.  No static, no sidetone.   The seller promptly issued a refund without requesting that the bad capsule be returned.

Yesterday I figured I had nothing to lose, so I took a crack at opening things up.  The tools I used were:  Channel locks to remove the entire transmitter base, a small screwdriver to pry off the filler cap, a plastic funnel for refilling, and needle nose pliers to re-crimp the cap.

Backing up a bit, when I removed the base, I found a neat cone-shaped mound of carbon.  I was expecting to find perhaps nothing, or a caked up consistency.  I dumped the mound of carbon into a small container and proceeded to tap out the remaining carbon inside the capsule until I heard nothing when shaking it.  The granules looked fine, although I had nothing to compare them to.

I reassembled the base and positioned the small plastic funnel over the fill hole.  The funnel was slightly larger than the hole but I held it firmly in place and tapped the side of the capsule to coax the carbon into the hole.  Those granules are jumpy!  Everything went back except some residual dust in the bowl.  I crimped the cap back on so it was tight enough not to turn.  I shook the capsule and it sounded like it should.  I was hopeful, but skeptical at the same time.

Amazingly, when I tried the re-filled capsule out in a 302, it sounded clearer than the existing capsule in that phone (an 11/39 that has been tested twice but never refilled). 

I guess the carbon was indeed caked up inside the capsule and simply needed a way out to disperse itself again.

I'm no longer afraid of this process after what seemed like a failure when trying something similar on a "bullet" type transmitter quite some time ago.  I guess I should have blamed the transmitter itself, since that type is so very inferior to the later F1s. 

My question is, are the correct tools out there that would make this operation more professional and easier/safer to perform?  I'm sure what I did yesterday was a vulgar insult to Bell System Practices and I'd like to do it the right way if there's a next time.  I have some other early F1s that could probably stand to have this same procedure performed on them, but I don't want to butcher them up in the process.

Thanks for any guidance or suggestions.

[poplar1]

I doubt that this was something techs did in the field, so it's probably not covered in the BSPs. It might be in the BSRS (Bell System Repair Specs) that were used in the WE Repair Shops--but so far these specs seem to be impossible to find.

[Matilo Telephones]

LOL rp2813 you seem to have the almost exact same experience as I had.

Simply the act of emptying out and putting back the granules makes the transmitter sound better than ever before.

Although I worked on a different type.

Does anybody else have experience with this? How long does such a repair hold?

[BDM]

I've never taken one apart for repair (a couple just to have a look around). But I have had experiences many times with low or non-working capsules. All of them F1s (6 or 7 of them in the last 20+ years). The ones that didn't function at all or very very little I would give a heavy "rap" on the side several times (not too hard so as to shock-damage the capsule or dent it). Then lightly kept tapping around the perimeter of the capsule. I remember one I must have spent 10/15 minutes doing that and it started working and worked fairly well. I've always assumed moisture had some how entered over time. Just enough to cause serious packing. Glad you had success trying this and thanks for posting your results.

P.S. I have one S.C. cartridge off a model 1243 I never could get working. Also several AE cartridges off AE40 models that never worked or were very poor/low sound quality. No amount of anything I did solved those issues.

[TelePlay]

I was just thinking, dangerous, I know, of what affect a ultrasonic cleaner would have on the carbon in the capsule if the transmitter module were placed in a water tight bag into an ultrasonic cleaner bath for 5 or 10  minutes, if that would have enough power to "sonicate" the granules enough to break them apart without having to take the transmitter apart? Anyone have a bad F1 and an ultrasonic cleaner to give that a try?

[BDM]

Interesting thought..

[Matilo Telephones]

Why put water in the ultrasonic cleaner and put the transmitter in a bag? Change the water for some other medium. Salt? Sand? Small ball barings?

[TelePlay]

Why put water in the ultrasonic cleaner and put the transmitter in a bag? Change the water for some other medium. Salt? Sand? Small ball barings?

If it will transmit the energy, sure, why not? Water would place the energy in 100% contact with the transmitter surface. Would also depend on the power of the ultrasonic cleaner. Anyone have the cleaner and a few poorly working F1s to experiment? 

Sand/salt etc would not provide 100% contact with all of the transmitter surface but the crystals are small enough that it may work. And you would still need to put the F1 in a bag to keep the sand/salt from getting into the transmitter, right?

[dsk]

What about using meths, and just drop the transmitter in it, it will dry out again?

dsk

[Matilo Telephones]

Meths? What is that? Sorry

[tallguy58]

Methamphetamines.

You can use it to repair phones and also make a bucket of money selling it to junkies.

[dsk]

  A little less common in some circles  methylated spirits, or denatured alcohol. 
Used for cleaning and stoves etc.

http://tinyurl.com/l8ja7dk

dsk

[Matilo Telephones]

I hoped you meant some kind of fluid and not some cristalline substance. :-)

It is called by another name here. Spiritus.

I hope to do some experiments with this later this year. First some other projects.

[TelePlay]

With the operation of an ultrasonic cleaner being the creation and self destruction of micro bubbles on the surface of the item being cleaned, I would think a heavier liquid, such as water would be vastly superior to a lighter, volatile solvent in which the bubbles created would cause micro heating and evaporation thereby using up some of the energy being transmitted by the cleaner's sonic transducers of the liquid meaning less energy would be left for vibrating the surface of the item in the bath, and in this case, creating micro bubbles on the surface of the transmitter hopefully causing the vibration of the bubble process to be transmitted into the transmitter capsule to break up the carbon particles.

The same with solids. A lot of energy would be wasted trying to move the solids before the vibrations reached the transmitter. Just seems a water based solution 100% in contact with the transmitter capsule cap would work best, if at all. A liquid that transmits well all of the energy to the F1 would be best. The thin plastic bag would be Glad Wrap or Saran Wrap to best allow most of the energy to be passed to the transmitter capsule and its contents with minimal loss of energy by the wrap and the bath medium.

Another thing that could be used is a hand held sonicator tip placed directly on the capsule area but those are not cheap and would only produce or transmit the high frequency vibrations at the single point where the metal tip contacted the transmitter.

An ultrasonic bath would be in near 100% contact will all of the transmitter in the bath, especially the capsule. I'd put it in the Saran Wrap with the capsule down and just submerge the back of the transmitter to ensure all of the energy generated be used on the capsule area. No need to vibrate the front of the F1 or its case, just the carbon filled capsule. Just thinking here based on past lab experience from long, long ago. Hope these thoughts help with your experiments.

[BDM]

Hey another thought. Get one of those old electric/vibrating football games, lay your broken/weak capsules on the playing field, flip the switch, presto, instant shake-up

https://www.youtube.com/watch?v=vgFZIS_a3CE