KLOK K7 broken from corrosive rot

[westdave]

I have a IN-18 clock in a aluminum case called Klok K7 (a wonderful case)

however after many years of service 4 out of the 6 tubes just went out (not blacked out but still clear) I disassembled the clock to see what's up? answer is! corrosion ,like some one had been dropping water in it for ten years, 

somehow the aluminum of the case reacted with the solder to become cottage cheese,print board,

after cleaning off the gunk, through out both boards ,upper and lower,including some sanding of printed ,board copper and the soldering of some lost copper with tiny wire,point to point,still 4 out of 6 no light ,time to pull out the meter ,

so I had 170 volts still working ,and I had the 5 volts needed for the IC's,tested near the hv resistors no voltage

on inspecting the three anodes there were no more thru holes to the other side of the board (eaten away forever)I sanded the copper print and added point to point wire and got the anodes back,now the 6 tubes lit and as a  precaution changed the 74141 IC's(they must have had a hard time ,replaced)but still a bit wonkey,i pulled the IN-18 tubes to look under neath , a whole bunch more cottage cheese rot,running pin to pin among the sockets (that's conductive crap on glass going pin to pin)(,more sanding,cleaning of the tubes them selfs,tested ,passed, test OK,clock restored, last bit, i sprayed plastic on both boards )covering the pins and sockets with tape before i sprayed them with plastic, in hopes it will arest the crud,and it will not form again

 so after many years this came out of no where (and if you also have a K7 you might check to see if it is OK or rotting before your eyes)

thanx the davester westdave

[gregebert]

I wonder if corrosive solder-flux was used. Did you see any telltale residue with a greenish tint ?

Was the damage confined to areas around electrolytic caps ? They do contain corrosive electrolyte and can fail over time.

The only other thing I can think of, and this is a long-shot, is ozone. If the case is tightly sealed it's possible the HV areas have a high enough field strength to some ozone. 

[Tidak Ada]

170V is far below the ozone risk, only in case of arcing it could be possible. Could it be some traces are too close together and be a possible source of arcing?

Many people in this modern semiconductor time aren't aware of the minimal safe distance between traces. Also nobody cares the voltage limits of a resistors. Not a point with a voltage of 170 volts, but working with CRT's and high speed dekatrons it may be quite an issue.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of gregebert
Sent: dinsdag 16 december 2014 16:34
To: neoni...@googlegroups.com
Subject: [neonixie-l] Re: KLOK K7 broken from corrosive rot

I wonder if corrosive solder-flux was used. Did you see any telltale residue with a greenish tint ?

Was the damage confined to areas around electrolytic caps ? They do contain corrosive electrolyte and can fail over time.

The only other thing I can think of, and this is a long-shot, is ozone. If the case is tightly sealed it's possible the HV areas have a high enough field strength to some ozone. 

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[robin bussell]

On 16/12/2014 15:33, gregebert wrote:
> I wonder if corrosive solder-flux was used. Did you see any telltale
> residue with a greenish tint ?
>
> Was the damage confined to areas around electrolytic caps ? They do
> contain corrosive electrolyte and can fail over time.
>

Also any Nicad backup battery can leak nasty copper eating stuff over
time too, I had to rescue a nice 80's synth from that once.

Cheers,
Robin.

[taylorjpt]

Aluminum and Lead and Tin all have different electrode potentials and will corrode when in direct contact.  When not in direct contact, the slightest condensation of atmospheric water forms an electrolyte which then attracts and holds more water due to the increased surface area and surface tension of the resulting corrosion products.  This can happen between metals held at the same external potential, i.e. no external potential.  Add even the slightest external voltage and now you have and electroplating system. 

When we were designing the first cell phones, even the 500-600mV microphone bias on the external connector resulted in the gold plated pins (All pins of the same metal) falling off of the connectors in a matter of weeks.  The solution was to ensure that all connector pins were at zero volts by periodically sampling the connector state, lowering the active duty cycles to a fraction of a percent.

[Tidak Ada]

Even the combination of copper and aluminum is highly corrosive in combination with water. It forms a electrochemical cell du to the difference in valence.

Copper is a semi noble metal, whereas aluminum is far away from the noble metals so copper and aluminum form a redox potential.

 

Never use copper bolts in aluminum, especially in humid environments! After some time you cannot loosen them and after a long time the aluminum around the bolt is rotten away.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of taylorjpt
Sent: dinsdag 16 december 2014 19:35
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Re: KLOK K7 broken from corrosive rot

Aluminum and Lead and Tin all have different electrode potentials and will corrode when in direct contact.  When not in direct contact, the slightest condensation of atmospheric water forms an electrolyte which then attracts and holds more water due to the increased surface area and surface tension of the resulting corrosion products.  This can happen between metals held at the same external potential, i.e. no external potential.  Add even the slightest external voltage and now you have and electroplating system. 

When we were designing the first cell phones, even the 500-600mV microphone bias on the external connector resulted in the gold plated pins (All pins of the same metal) falling off of the connectors in a matter of weeks.  The solution was to ensure that all connector pins were at zero volts by periodically sampling the connector state, lowering the active duty cycles to a fraction of a percent.

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[Sir Melon]

Might be a good idea to keep it somewhere safer, fires and electricity...
Hopefully the looks of it won't be damaged!

[Dman777]

I would like to know also if the "cottage cheese" corrosion look would be from solder-flux, also. I have a Z5660 Nixie clock from PV Electronics that Pete soldered together. It's an excellent clock and I love it, but Pete left a ton of solder-flux on it and I have yet to remove it myself. 

-Darin

[Nicholas Stock]

The solder flux won't do anything untoward in my experience. I still have amplifiers I put together over 25 years ago without cleaning the flux off them and they work fine...if it bothers you so much, take the tubes out and the PCB from the case and get an old toothbrush, some isopropyl alcohol and gently scrub the stuff away and wash with fresh isopropyl alcohol afterwards. It'll take a few go's to get it nice and clean.

On Thu, Dec 18, 2014 at 4:57 PM, Dman777 <darin....@gmail.com> wrote:

I would like to know also if the "cottage cheese" corrosion look would be from solder-flux, also. I have a Z5660 Nixie clock from PV Electronics that Pete soldered together. It's an excellent clock and I love it, but Pete left a ton of solder-flux on it and I have yet to remove it myself. 

-Darin

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[Nick]

....if using Isopropyl alcohol, aka IPA, make sure you do it in a well ventilated area.

IPA will give you a blinding/pounding headache and is not nice stuff. ..

[David Forbes]

There are two types of solder flux. The old rosin-core flux is inert.

The newer organic flux is corrosive and would result in the sort of
damage described in this clock. It needs to be washed off in hot water
soon after use.

On 12/18/14 9:39 PM, Nicholas Stock wrote:
> The solder flux won't do anything untoward in my experience. I still
> have amplifiers I put together over 25 years ago without cleaning the
> flux off them and they work fine...if it bothers you so much, take the
> tubes out and the PCB from the case and get an old toothbrush, some
> isopropyl alcohol and gently scrub the stuff away and wash with fresh
> isopropyl alcohol afterwards. It'll take a few go's to get it nice and
> clean.

--
David Forbes, Tucson AZ

[Nicholas Stock]

I quite like the smell of IPA, but then again I'm a chemist, so I would..;-) As solvents go, it's fairly innocuous, but poison is always in the dose, so Nick makes a good point, use it in a well ventilated area.

On Fri, Dec 19, 2014 at 1:14 PM, Nick <ni...@desmith.net> wrote:

....if using Isopropyl alcohol, aka IPA, make sure you do it in a well ventilated area.

IPA will give you a blinding/pounding headache and is not nice stuff. ..

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[Instrument Resources of America]

I've been sniffing it for years, and there's nothing wrong with, wrong with, wrong with, wrong with, me!!  Ira.

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[gregebert]

I prefer the aerosol flux-removal solvents (ethanol rather than isopropyl), but I found that simply spraying the board is NOT sufficient; you need to scrub the board before the solvent evaporates. Cotton swabs are effective, but they leave annoying fibers on the board.

Rinsing the solvent+flux under hot-water did not work, either.

Years ago Radio Shack sold an excellent aerosol flux remover, but it's no longer available. I used it on several boards and it rinsed-away all of the flux without leaving any residue.

If anyone has a better technique, let me know.

[Instrument Resources of America]

As others have already mentioned, the Isopropyl Alcohol and a toothbrush do work quite well. More Isopropyl in a spray bottle, can then be used to flush it all away. Leaves it nice and clean.    Ira.

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[Charles MacDonald]

On 14-12-19 06:47 PM, gregebert wrote:

> Years ago Radio Shack sold an excellent aerosol flux remover, but it's
> no longer available. I used it on several boards and it rinsed-away all
> of the flux without leaving any residue.

Probably http://en.wikipedia.org/wiki/1,1,1-Trichloroethane
unfortunately no longer available as a general purpose solvent.


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[JohnK]

There are no-clean fluxes that definitely cause no probs in twenty-odd years
that I have observed them. And water wash ones too. BUT they need very
'fresh' components for them to be OK in manufacturing. [Speaking from
experience in an electronics factory].

John k.

----- Original Message -----
From: "David Forbes" <dfo...@dakotacom.net>
To: <neoni...@googlegroups.com>
Sent: Saturday, December 20, 2014 9:49 AM
Subject: Re: [neonixie-l] Re: KLOK K7 broken from corrosive rot

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[JohnK]

Iso-propyl is/was called rubbing alcohol [and used as such in the sports
industry].

John K

----- Original Message -----
From: "Nick" <ni...@desmith.net>
To: <neoni...@googlegroups.com>
Sent: Saturday, December 20, 2014 7:44 AM
Subject: Re: [neonixie-l] Re: KLOK K7 broken from corrosive rot

> ....if using Isopropyl alcohol, aka IPA, make sure you do it in a well
> ventilated area.
>
> IPA will give you a blinding/pounding headache and is not nice stuff. ..
>

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> https://groups.google.com/d/msgid/neonixie-l/85ad039c-ea50-4e40-ad64-c1d1a91d0196%40googlegroups.com.

[Nick]

On Saturday, 20 December 2014 16:18:47 UTC, johnk wrote:

Iso-propyl is/was called rubbing alcohol [and used as such in the sports
industry].

"Rubbing Alcohol" can be either 70% IPA or 70% ethyl alcohol (ethanol) which has been denatured. The formulation is up to the individual manufacturer. The "denatured" moniker means that it has additives that make it very nasty for human consumption (bad tasting, foul smelling, emetic etc.) to discourage abuse.

IPA will still give you a nasty headache even from just breathing fumes whilst cleaning stuff. Been there. Done that. Felt awful!

I fully agree that IPA + old toothbrush is a good combination.

Nick

[michael ohara]

Hewlett-Packard ran tests, and found that the flux left on the board protected the board from corrosion.
Some vintage HP boards are actually coated with flux (Boards from the late nixie-early IC era)