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Author Topic: U47 Tube Socket Restoration or Replacement?  (Read 1484 times)

Jim Williams

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Re: U47 Tube Socket Refurb/Replace
« Reply #15 on: May 31, 2020, 12:08:00 pm »

AS far as I know, it's the mismatch o metals that causes the leaching problems.  So unless you are going to re-plate your vf14 pins gold ( :-[), then I'd stick with silver.  There are other reasons why silver was chosen as well... maybe because of its lower resistance.

The term is called "metal migration". It's the effect of dissimilar alloys reacting and separating. It's best to mate similar metals whether gold, silver or tin/lead. Otherwise, wiggle the tube in the socket to scape off the corrosion every few months.
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Kai

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Re: U47 Tube Socket Refurb/Replace
« Reply #16 on: June 01, 2020, 06:58:48 am »

The term is called "metal migration". It's the effect of dissimilar alloys reacting and separating. It's best to mate similar metals whether gold, silver or tin/lead. Otherwise, wiggle the tube in the socket to scape off the corrosion every few months.
Wiggling, as mentioned, isn't a permanent solution.
Thoroughly cleaning, or if contacts are too worn out, replacing the socket is.
You don't want the microphone to start crackling in the middle of a session.

I have a easy time getting as many of these sockets from eBay as I like for cheap. They turn up quite often, at least here in Germany.

Usually they have to be cleaned.

I spray the contacts with Kontact 60 after removing them, after an hour a tiny brush or Q-tips to remove anything non metallic.
Then spray the socket and contacts with brake cleaner, followed by a good scrub with isopropy alcohol + water to regain good isolation and hundred percent removal of the Kontact 60, because it will eat the coating if left alone.

The quality of contacting metal to metal has a lot to do with enough contact force.
Sometimes the contacts have to be slightly bent to do that.

Tube contacts are dry wiped, very carefully.
I never had metal bottle tubes with contacts that looked oxidized, even on rusty tubes!
Better materials, obviously, German military grade for marines.


I don't know of anything that can be applied to the contacts that does not vaporize under the heat conditions, leaving residue that is making things worse.,
So I leave it alone, never have any problems again usually.

Under no circumstances anything may be applied to the tube itself, it can creep between the contacts and housing and kill the tube.
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DanDan

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Re: U47 Tube Socket Refurb/Replace
« Reply #17 on: June 01, 2020, 11:44:39 am »

Wow, I had nearly forgotten what a good forum can do...
Thank you for those helpful thoughts.

Kai, do you buy actual Preh Sockets? Next time you see one, could you please post a link here. I will be notified. I will also reach out to some German friends at Vertigo and Mr. Grosser.

I think a new socket, carefully cleaned has to be the ideal solution.
I have Kontakt Gold 2000, a bit old. OK to use?

Jim, I will resolder using silver solder. If I wait until I can get the mic to Andreas, I will bring that up for his consideration.

All, please don't be confused by my wandering style. This U47 is new to me. I have two 67's for years.
They both crackle now and then. I clean the valve pins and the sockets to some extent with Isopropyl and Kontakt.
I have left the Kontakt on there it seems mistakenly. I thought it best to let it continue doing it's thing, and work as a lubricant.
This cleaning tends to work, for a while, but perhaps it has as much to do with the physical wiggling the tube out and then in again.
If the noise starts up at an actual session, I shut down the mic, use the other one perhaps, or let it cool and give it a little wiggle.

This work, for now, but I am really considering a Gold Plated Teflon Socket.
I know Silver is more conductive, but surely in context that is a minuscule difference. Gold seems much less prone to tarnish. 





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Dan FitzGerald  MIOA MAES
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klaus

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Re: U47 Tube Socket Refurb/Replace
« Reply #18 on: June 01, 2020, 02:07:57 pm »

I repeat: I see no need to replace an original Neumann U67 tube socket. They have ever failed for me in 35 years of regular. servicing. I have not found a single tube crackle in a U67 that was caused by a deficient tube socket.
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Klaus Heyne
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DanDan

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #19 on: June 01, 2020, 05:08:03 pm »

I noted that well Klaus. But the observed behaviour over time is factual too. I am trying to find solutions here, so all facts are welcome.
Ultimately whatever is going on has to fit all the facts. I have enough tubes to be pretty sure they are not all faulty.  And wiggling the tube as Jim also finds,  can and does stop the noise. That suggests to me socket or pins.
When cleaning the EF pins and sockets to some extent, perhaps I should not have left Kontakt to soak on there.


DD
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Dan FitzGerald  MIOA MAES
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Kai

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #20 on: June 01, 2020, 05:28:09 pm »

I was talking U47.

U67 is a completely different story.
The small pins of these type of glass tubes get oxidized or sulfurized all the time.
They even get much hotter.

The socket holes are too small to do anything mechanical for cleaning the contacts, except maybe you can try with ultrasonics or 24h in strong desoxy (Kontakt 60, Caramba,.. ) and special cleaner afterwards:
brake cleaner and washing with isopropyl alcohol/destilled water, then pure alcohol to remove the water, long dry.
 
Kontakt Gold does nothing good in cleaning oxidized contacts, it's meant to be protection for Chinch connectors by greasing them.

I'd start with cleaning the tube pins.
Glass tubes don't need to be handled extremly carefully, in the unlikely case the EF86 (or whatever made it's way into the mic over time) is damaged, it's replacable.
Leave no residue of cleaner, or the pins will oxidize again soon.

If you already contaminated the socket contacts there's no way round removing and either clean (see above) or replace it.
Hopefully you did not really spray into the mic, else everything inside is contaminated and needs checking and washing.

For soldering I'd stay with standard 60/40m tin/lead electronic solder.
If you feel better use silver, anyway so called "silver" solder contains few % of silver only, rest is tin usually.
If you go that route I'd use the stuff that is manufactured at full moon (or was it new moon?) by blond virgins :) - sorry, I couldn't hesitate.

The flux with some silver solders is a bit suspicious, needs cleaning after soldering - hard to do inside the mic and unneccessary hassle IMO.


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DanDan

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #21 on: June 01, 2020, 05:57:02 pm »

Regarding the 67's:
I will get some Kontakt 60. I doubt if the Kontakt Gold 2000 has done any harm. The spec does say it is particularly suitable for lubrication and protection of soft metal plated contacts e.g. Silver. It's been a while, but there is no way I sprayed it willy nilly around the Mic.  For the sockets I would have used a drop on a cotton bud or just left some on the valve pins when reinserting. Do you really think they need to be removed and cleaned at all? I have access to an Ultrasonic bath. But I have no idea what desoxy is, or special cleaner? Also from earlier,  brake cleaner?
The valves I have are mostly NOS Telefunken EF806S. One is a National which came in the 90's 67 reissue.

Back to 47:
I think lead solder is illegal in the EU these days, but I have both in any case, and it seems to make sense to mate silver with the remaining thin silver on the sockets.

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Dan FitzGerald  MIOA MAES
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Kai

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #22 on: June 01, 2020, 06:13:03 pm »

The Kontakt Gold probably has converted to a nice tar coating on the socket contacts.

Strong desoxy e.g. is Kontakt 60 or the stuff you find with car repair, e.g. Caramba, but NOT WD40.
I'd go with Kontakt 60, it eats everything, included it's own can (over 10 years or so).
Brake cleaner is the best and cheapest solvent to degrease something after desoxy, again easily obtainable.
There's expensive stuff for electronic board cleaning too, over the top IMO.

For repair of pre-lead-free equipment lead solder still is allowed in EU, for a good reason: don't mix solders, joints may break over time by termal stress.
The U67 is constructed for 60/39/1 Sn/Pb/Cu solder and collophonium flux.
Anyway the U67 contains lead, so it becomes "hazardous waste" at the end of it's lifetime, in 200 year :)
Or will end up in a museum.
Or will be restored for someone recording music.
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DanDan

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #23 on: June 01, 2020, 06:48:35 pm »

67-
LOL, so optimistic!  I took a look just now. There is no contaminant visible anywhere on the Teflon on on the PC board.   But interestingly, as you said, the EF806S Pins are not at all shiny. I gave them a little Isopropy on a bud. No visible contaminant came off but they did become visibly cleaner when I persisted. That sounds like your 'tar' no?  Now they are a cleaner looking, a little shiny but  just have that slight rainbow colouring which valve pins get from heat I presume.  I can't see anything inside the gold sockets but I am thinking it would probably be best to replace them if Neumann will supply new ones. Seems we have an answer, idiot used wrong Kontakt!
I will order Kontakt 60 now for the valve pins. Also brake degreaser.  I won't mix solders on your advice.

47- Just got a very speedy answer from Tele USA. Although not advertised they do indeed sell their Teflon and Gold y8A. Also the soft sponge tube support.

Klaus, should we change the thread title?  47/67 Tube Socket issues. Or blond bimbo buys wrong cleaning product.... Perhaps the thread will serve as a cautionary but ultimately advisory tale that asking first is wise and gets very real valuable answers for all you kind folks here.

All good, DD
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Dan FitzGerald  MIOA MAES
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gtoledo3

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #24 on: June 01, 2020, 07:16:55 pm »

I have had good results with DeOxit, though I use the red version that comes in a bottle, sparingly. If I apply more to areas, to help break up corrosion more, I clean it up before running the gear. I might put the tube in and out of the socket a couple times, gently.

I usually find myself doing this with sockets, but I have done it with tube pins as well. Again, sparingly as I can, and with cleanup.

I think sometimes very light oxidation seems to just burn off with a little time if you’re lucky.

And to be clear, I am just talking about “in general”, NOT the Neumann sockets. I post this because mainly because I would be extremely reticent to use some of the heavy duty treatments mentioned here on ANY tube socket. So I mention this as something I have seen to not have detriment over long term (seemingly), and where I know another few people who have done similarly.
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RadarDoug2

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #25 on: June 01, 2020, 07:25:40 pm »

As Klaus has said, the sockets in a U67 dont go faulty. I have had occasion to increase the tension on them. By very carefully with a small screwdriver, poking it down the side of the socket in the holder. This also works on Tuchels. Also, you can very slightly bend the pins on the valves so they impart tension. Sticking liquid cleaner in things is always risky.
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klaus

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #26 on: June 01, 2020, 07:37:06 pm »

Quote
47- Just got a very speedy answer from Tele USA. Although not advertised they do indeed sell their Teflon and Gold y8A. Also the soft sponge tube support.

Please read what I wrote about aftermarket octagonal sockets.

Quote
Klaus, should we change the thread title?  47/67 Tube Socket issues. Or blond bimbo buys wrong cleaning product.... Perhaps the thread will serve as a cautionary but ultimately advisory tale that asking first is wise and gets very real valuable answers for all you kind folks here.

The problem (intermittent, oxidized U67 tube sockets) and its solution (applying all kinds of goo to the contact surfaces) don't compute with my experience, which, for the third time, is that the tube sockets Neumann has used throughout the life of U67 do not corrode.

So this opinion will not be part of any advisory I agree with or approve, and therefore warranting a title change. But I'll leave it up, for now, as opinions to air on the subject.

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Klaus Heyne
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DanDan

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #27 on: June 01, 2020, 07:42:04 pm »

Klaus please trust that I really do  hear you, loud and clear, and greatly appreciate your generosity in sharing.  If I invest in a Tele USA socket it will be to give me time to deal with the existing socket or send it to an expert, and or  find a NOS Preh.

67s
Kontakt 60 is available by mail within Ireland, Caig no.
Klaus assurance that those 67 Teflon Gold sockets do not cause trouble, conflated with Kai's suggestion that the erroneous  Kontakt Gold 2000 has probably dried and turned into something unwelcome strongly suggests that I have done some harm. i.e. Contaminated both the gold contacts AND tube pins.    I will see if I can get new sockets from Neumann. If not thorough cleaning and degreasing as per Kai.
FYI I did look at one of my unused EF806S Tele's. The pins do appear to be a little bit dull so definitely some deox and cleaning before deploying in the future. Can't do any harm right? 

The 47. Luckily I asked here and  have not touched it. Hopefully it will be possible to bring it to Andreas soon.

Tx to all, warm regards, DD
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Dan FitzGerald  MIOA MAES
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afterlifestudios

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #28 on: June 01, 2020, 08:01:27 pm »

Curious to hear a little more about Kai’s vf14 socket re-tensioning success.  Do you just go by feel?  Your emphasis of the word “slightly” makes me wonder if there’s anything in particular to watch for?  What’s your implement of choice for bending the contact pins?
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Kai

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Re: U47 Tube Socket Restoration or Replacement?
« Reply #29 on: June 02, 2020, 02:02:04 am »

Tensioning tube socket contacts:
• If you don't have problems - don't do it.
• With contacts easily visible, compare and equalize the open space for the tube pins to match the one with the smallest opening - not more.
• Too much bending back and forth weekens the spring effect.

If you want too much you get less.
Inserting the tube bends back a contact spring if its material is stressed outside the "elastic-" into the "plastic range".

• If bent, carefully straighten the pins on glass tubes WITHOUT APPLYING MUCH FORCE TO THE GLASS.
Straight pins give equal contact force within the socket.
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