Malfunctioning Potted Relays: Emergency Repair in the No. 5 Crossbar 

I love learning from you and would gladly listen to your explanations of things like this for hours ☺️👍

I have seen many old plastics dissolve into goo over time. One example is the platen rollers in military AN/UGC-74A radioteletype units that radio amateurs are interested in. The Museum of Modern Art in NYC had a problem with many old plastic items disintegrating as well. I wonder if there is a way of sealing the gap on those relays between the phenolic base and aluminum can, perhaps with a high quality silicone bead after cleaning to assure good adhesion. It might be possible to do this without having to bend the aluminum can tabs, purely from the outside, but of course if you did open them and clean then seal with a silicone or acrylic adhesive it would be more foolproof. If you want me to play with it a bit PM me and you could send me a couple of defective relays that are leaking and I could try a couple of ideas and then send them back to you to check out. It might just work. I'd like to see these old systems continue on and I am grateful to have been able to play with when they were in common use.

I would avoid touching the goo as who knows if it's some sort of nasty toxic material

What is the goo made of? The green looks like coppersalts.

The trouble cards are still being used as intended, they're detecting trouble!

7:31 the excitement and energy of “LOOK AT HOW MUCH GOO I GOT IN ONE GO” has improved my mood so much

Loved the vibe of the coffee break chat! Possible new regular video segment? The comparison with friends/loved ones was great. I’ve always found it hard to describe that spidey sense of walking into the exchange and just knowing it’s not right! Thankfully none of the strowger exchanges I look after here in the UK have potted relays similar potting may have been used in TXE exchanges over here, but being 60s/70s … those are too modern for me!

I also had trouble with captions on my video today. I'm glad to see I was not the only one! Fran Blanche also did a video about the green slime and how it affected the power cord of her guitar amplifier.

As the son of a 42-year Bell Labs/WE employee who retired in '69, I have not seen a failure like the breakdown of potting of the 316 relay in all the stuff dad brought home. How insidious. As you worked on the wiring, I asked myself "what happens when the wires break?" and sure enough they did. You are doing God's work- very nicely done! ps You will never forget to make sure that spring steel is seated again...

The goo is almost certainly plasticizer. The potting compound used is likely a polyvinyl (PVC) or perhaps polyethylene (PEN), and as it ages (accelerated by heat), it breaks down into its components and the plasticizer, which is slightly conductive, leaks. The green color comes from the copper it’s leaching on the way out of the relay. Soap and water won’t touch this. Definitely try something stronger to clean it: brake cleaner comes to mind (try the environmentally friendly stuff first, and if that doesn’t shift it, try the chlorinated stuff in a red can).

We used to attack messes like that with 1,1,1, trichloroethylene spray (we called it "Instant Switchman"). Black and white spray cans from WeCo by the case. The liquid also came in brown pint bottles through 55 gallon drums for when things really got serious in a #1 SXS. Thing is, methyl chloroform or fluorinated methyl chloroform is nasty stuff, even though we sometimes almost bathed in it. Hopefully there is currently some sort of reasonably safe solvent that can be used to detail clean your wire-spring relays and other gear.

That goo looks very similar to the decomposing PVC that I see in molded electrical plugs from this vintage. The plastic decomposes back into liquid monomers and seeps out around the pins.

Every single switch I worked in had it's own personality, and a person who knew a particular switch could sense instantly if it was healthy and happy - or not.

Let me say one simple thing, if anyone here is transphobic, you're not gonna like my comment at all. First off, Sarah and Claire. You two are an amazing and hilarious duo, but seeing you two stand proud made me want to get out of my shell and be proud of who I am. It's really hard to explain exactly what comes to mind, but I really can only describe it as this: I am a proud MtF Transgender woman, my voice may not be the smoothest, and I may not have the best curves or clearest skin out on the street, but any time I watch any of these videos, it re-establishes that I'm not alone by any means, and should only be afraid of fear itself. Thank you Claire and Sarah, for giving me the inspiration to grow into the unique, and beautiful woman I am today. (My profile pic has yet to be updated, but that is coming soon) May you fantastic people live healthy and long lives, and be prosperous in all of which you challenge yourselves to. Much love! -A boy that was, But woman that is.

May I say: That rainbow sweater looks absolutely fabolous :-) Also love the troubleshooting videos, I find fixing old gear fascinating.

(I'm an old telecom guy and spent time as MTS at Bell Labs.) I am just amazed at the breadth of knowledge that you have with such a range of equipment.

sort of reminds me of a Plessey crossbar PABX in the UK I looked after back in the eighties. We never had green goop problems but during its lifetime it had a major upgrade , peformed by the factory techicians . As art of that they were very liberal with the contact cleaner spray. That as great when they were there and it was ok for about 3 months afterwards. Unfortunately the Cleaner acted as a pretty effective insulator when it reacted with some of the contacts . Kept me and my colleagues busy for months afterwards ! . Love the channel and it interesting to see how things were different but still the same over the pond

Gotta say, watching you use those test frames is like watching a master organist play. Thanks for making these videos!

Had a goo problem back in 1970 at one of the first GSC crossbar exchanges being installed in Wales. The goo appeared under the residual studs on relay armatures causing them to stick on. The problem was caused by fumes from the moulded plastic shelf covers reacting with the stud. The covers were replaced with glass covers in metal frames and the problem was solved. The plastic covers were very popular as garden cloches.

I love how excited Claire is about the goop! Keep up your awesome work people!

Fascinating maintenance video about this old equipment. Sounds like you guys have the same aging plastic problem as NASA. Plastic chemistry delivers great products but it does not age gracefully over the decades causing nightmares for museums.

I really enjoyed the discussion on polar relays. In the summer of 1966 I was 14 years old and the CO in Cle Elum was being converted from switchboard to step-by-step. I spent most of the summer hanging around the work and begging parts from the old office. I got a bunch of polar relays and arranged them as a 10-bit memory for the computer I was going to build. The computer never got past the working 10 bit memory, but I did have a lot of fun with several different types of relays.

As someone who has worked on old electronics I want to ask, is it carcinogenic or mutagenic? What does it taste like?

Take care, i think you might want to avoid skin exposure to that crap.

For a decomposing polymer like that, I would definitely second the recommendation of using acetone or some other strong solvent to clean that off. Easier, cleaner too.

Please be careful with the goo! I don't know about this goo, but similar goo used in transformers of that era used Polychlorinated biphenyls (PCBs) as fire retardent - nasty stuff!

I have always enjoyed your videos, as I used to work on a SXS in college. Your mention of detecting trouble by sounds reminds me of the most distressing telephone exchange tour I ever took. It was a Bell System SXS that had digit-absorbing first selectors. Their operation of stepping up to a level, stepping in one position, and then dropping back sounded exactly the same as a malfunctioning switch. Breaking wire-wrapped wires is also familiar. i found that the best thing to do was to quit for the day and try again tomorrow. I still believe that I saved the company money by doing so, besides saving my sanity.

Where did you get that rainbow sweater? I must have one!

Sarah, Claire, Astrid, et.all...Excellent video! Thank you so much for posting. +1 on the nice sweater. :) Everybody else commenting, THANK YOU! Here, within hours, from places all over the world, there have been plenty of analysis, suggestions for repair/cean-up/personal safety, and useful anecdotes, to help with the problem and illuminate the viewership. It's very appreciated. I've been lucky to have visited the museum once, in the summer of 2018. If you get a chance to go, by all means do, it is an incredible place, and that the gear works AND is in operation for the museum goers makes it truly special. Thanks to all who make it happen.

Q: Where do telephone museum curators store their old relays? A: In their trunk. …Sorry. The green goo, btw, is from the Cretaceous period. 🦖 🦖 It’s just trying to find its way back home. These chill miscellaneous repair & maintenance videos are awesome! If you post them, I will watch them. (And find a way to turn them into dad jokes)

I don't know much about this stuff but I have to say your dedication to keeping this stuff working is second to none! That goo looks like a nightmare. Really well explained.

Got the info in that goo... diisooctyl phthalate. It is a product of PVC insulation and /hot/ copper.

Seems to me that an ultrasonic tank could clean those open relays without disassembly, saving hours of frustration. They are certainly not too uncommon or expensive today. I can't say which surfactant or solvent would work best with your plasticizer while keeping the fumes and fire hazard to a minimum.

You girls are really very symphatic and know your stuff.

0:40 The potting material is leaking from the two empty holes on the back of the relay. That is where it was initially filled with the potting material. Plug the holes, such as by threading the holes and inserting short bolts with a rubber washer seal. Also wrap the metal and plastic seam with a waterproofing silicone tape. US Patent 4134088 by Bell Labs - 1977 - A pair of apertures 34 and 35 provide access to the interior of enclosure 33 for the introduction, for example, of a potting compound 36, a portion of which is represented in the drawing. US Patent 2882505 by Bell Labs - 1959 - The potting composition of the present invention possesses an extremely desirable combination of these requisite characteristics. It consists of a mass of fine particles of fused alumina, each particle preferably being coated with a cured silicone resin. Bell Laboratories Record Volume XXXI No 11, Nov 1953, page 462, potting with wax using a hospital centrifuge.

Instead of goof off try an automotive product known as Brakleen its is an aerosol spray but cleans the green goo up extremely well and is safe on plastics. Make sure the power is off on XB as it is may flash on you. If you are dis assembling the relays to clean them you can use lacquer thinner as well. Both products put off fumes so make sure you use ppe.

do you and Claire have matching glasses or do you share the same pair? :D :D:D

Have you considered using heat shrink tubing over the entire outer case of the plug-in relays? This would contain the GOO within the heat shrink tubing. Simply remove the relay, apply the heat shrink, plug the relay back in. Hope this helps. Great videos. Just discovered your channel.

I wonder if you reached out to WE and told them about the project if they would send some spares for publicity, or help you out, haha

I adore the way you show, explain, examine and do the things you do. I learn so much watching your videos. You could do a video each day and I’d watch them all as soon as they are being posted. Keep on !

Ew, dissolved rubber in old electronic equipment is one of the most annoying and disgusting things to work with, my condolences :/ I've found the best medicine to remove, say, goopified tape deck belts and soft-touch plastics and other, similar kinds of schmoo from electronics is naphtha (zippo lighter juice or Coleman fuel, Coleman's cheaper than Kleen-Strip naphtha somehow despite being the same stuff but I like the zippo bottles for dispensing) to get it off around delicate things like, say, the solenoid coils in those open relays where you don't wanna eat the shellac off the coil windings, and for hard surfaces that can take harsh solvents it's usually best to just take em outside and hose em down with Brakleen. For getting it off your hands, I recommend wiping the big chunks off with a shop towel and then using a buncha baby oil/vaseline/crisco to soften and un-sticky-ify it til you can get the rest off with a napkin or something.

I can certainly understand being conservative about spare parts, I have a good stock of wipers and cords for my SXS but it's always on my mind that what I've got may be all I'll ever have.

I reckon there must be a liquid you could immerse the relays into to easily dissolve the goo. Then it would just be a matter of using contact cleaner on the contacts to remove any leftover traces. Acetone is harsh, but only on some modern plastics. It evaporates quickly and is cheap. Any other cleaner recommendation for full immersion?

Take out your leaky relays, clean them up, scuff them up a little bit and apply something called "shoe goo" around the area to seal it. Shoe goo is like a cross between caulk and super glue. I sealed a bike tire with a large hole, with nothing but shoe goo 3 years ago and it's still holding air. I also patched a few holes in my inflatable hot tub. I patched a pinky sized hole, it's been holding for a year now

would cleaning the relays in an ultrasonic cleaner full of solvent (spirits, Isopropanol, ...) work ?

Cool stuff. So many switches and buttons. Thx for cool 😎 video 📹 ♥ from Pennsylvania 📞

Surely an ultrasonic cleaner with an appropriate solvent would be an easier way to clean this? Lots of comments, sorry if someone already mentioned that.

I would love to take a trip to Seattle and see the Museum and meet Sara, Astrid, Claire, and the rest of the team. Analog phone technology has been fascinating to me for many years, and I'd love to pick your brains and see all this equipment. Do y'all (I'm in Asheville, NC) offer personal tours in blocks of time? Thank you all so much for a) building your knowledge of equipment like this, b) making the videos about it, and c) sharing your knowledge and time with Museum visitors.

i see sarah has stolen claire's colourful cardigan :D

As a switching tech in the 70's, I used a 35f test set on those 280 type relays quite alot which set certain currents to the relay like "soak, no operate, soak, operate" etc. If a tiny metal burr come off between the adjustment tool and magnetic post, it would throw off the settings. Especially if you didnt see it -- like me. Fun days working on those. Thank you for the video. Excellent.

Thanks for sharing this repair! I hate it when things start releasing goo! That happens with old plastics and it makes a terrible mess! Also I love your sweater. it grabbed my attention and is so cheerful!

This may sound weird, but that looks like the composition used in old printing rollers. If it got too warm they were given to melting. The stuff looked just like that, and behaves just like it. en.wikipedia.org/wiki/Composition_roller

Awesome sweater and eyeglasses!!!!

i love these troubleshooting videos they are so damn interesting... every step explained so expertly. Oh and I love the rainbow sweater too.

The dreaded goop! I first encountered that stuff in one of my payphones. Fun stuff. I wonder what it actually is?

Next time you have an Australian through the museum (hopefully me, but I doubt I'll be lucky enough to get up there this year) ask them about Telstra's water sealant from the early-mid oughts that went conductive over time.

I worked for Nextel as a contractor back in the early 80s as a trunk room Tech (my dad used to work for them too & got me the temporary job) so that green stuff, if I remember it is inside those cans as a vibration insulator to contains the mercury-filled glass microswitches

Have you thought about experimenting with a sealant.. perhaps a spray of a thin layer of clear rubberized coating on the leaking relay to forestall future leakage. Not sure if it would work but might be worth a try on one or two relays as I don’t see a down side.

For gloves, not sure if they're compatable with whatever that goo is but Ansell Microflex 93-260 are pretty damn durable but still reasonably tactile, they are pretty damn pricy (around $60 AUD for 50 pces) but atleast for me they work super good enough for bulk photography chemical handling and nitro glow motors

mm yummers the forbidden lime jelly

I don't know when I've last seen this stuff, but I certainly remember it as being absolutely disgusting and a HUGE pain to clean up. I feel sorry for anyone who has to deal with this stuff regularly! I think I once had a bad transformer from a water boiler control (that even was quite new, like less than 30 years) that leaked a brown version of this gunk, and another older transformer that leaked the same green gunk. In european HVAC, this sort of issue is actually not even that rare while the equipment is still in use, as stuff like pumps, radiators and boilers is usually run until all spare parts are used up or it fails from old age, and many plastics, capacitors, hoses, etc... are not meant for 20-50 years of nonstop use in extreme heat and vibration, so decomposing plastics, cracking hoses, dry bearings, leaking O-rings, glue peeling up and other fails and breakdowns related to polymers aging and decomposing are kind of common on older heating systems. In fact, they are usually the main reason why an old boiler is eventually replaced, as these problems just become too common as the thing ages, and reliability thus also gets worse over time, until the owner gets fed up with the constant breakdowns and gets it replaced.

12:39 - I'd recommend seeing if an ULTRASONIC cleaner would be useful for that. High end ones are EXPENSIVE ($1200), but "economy" ones are around $450. They might be able to handle cleaning, albeit idk how durable the relays are.

Maybe an ultrasonic cleaner with WD40 or similar solvent instead of water. You may even get away without disassembly of the springset. I worked in the UK back in the 70's on crossbar TXK3. Loved it ! Keep up the great work. 👍

12:31 - You can MAKE a jig for those pretty easily out of WOOD and small metal brackets and a dremel/file. If this is routine for the operation of the museum -- i'd recommend making one, and then possibly CASTING one with resin / metal.

Just an idea...maybe you could take some clear fiber 1/2 inch tape and wrap around the joint of the relays to prevent the leaking? Give a few a try.

09:32 - I see the video is 1+yr old; IDK how I missed this one! I was a 1990's/early 2k00's phreak (and still a current subscriber of Emanual's finest quarterly mag, 2600), & I find these videos ludicrously educational & entertaining. But I (often) digress - Did you ever find out what the goop consists of? Ever consider maybe taking donations to pay a local-to-you lab to run a GCMS on it, & then we'll get a comprehensive list of constituent chemicals/compounds? Just a thought. My curiousity is wide-open-throttle on this one.

These are great videos! I knew that the telephone network was complex, but this is amazing. Also amazing is your, and the other's knowledge of how these systems work. Keep up the great work. Too bad you're on the west coast, or I would definitely come and visit. Bravo!

Watching Sarah Dance accross that test frame, reminds me of the STNG scene with Data "Life.. forms.... Tiny .. little ... life forms" ...

When I worked at Chicago #1 telegraph I had the opportunity to "box" polar relays, specifically the 209A type. It was a delicate job and a "few" relays found their way to the Chicago river. The mercury wetted polar relays were a godsend. When they acted up you just pulled them and tapped them on the floor and they were good to go.

In my years working on Northern Electric #5 Crossbar switches I don’t ever recall seeing the green goop. But I do remember the polarized relays.

Thinking about how the late '80s PCM switch I used to maintain didn't leak any green goo, but it had a lot of parts that we couldn't do anything to repair, like custom ASICs and ultra-rare LSI chips.

I really love the rainbow jumper. I also have a rainbow jacket. I hope the green goo is not toxic. And I’m impressed by the rigorous troubleshooting methods. The wiring looks almost impossible to figure out.

8:32 - You probably should be using "blue shop towels" for that -- they hold up better and don't give possibility of erroneous fibers into the electronics. Obv more expensive than paper towels and idk your budget of course.

Have you tried solvents like isopropyl alcohol, toluene, or flux remover? These are safe for most electronics. some paints or inks can be damaged.

Not against "Green Goo" but against other Nasty Gooey messes, found a good quality ultrasonic cleaner and a bottle of Isopro Alcohol does WONDERS...

Especially given the era, you might want to send a sample of that off for analysis. They had a number of quite nasty plasticizers back then, and even if not, it would probably give you an accurate picture of what solvent might best attack the goo.

We find this Green Goo in the Uk on PVC cables manafactured in the 1960's I understand its a "degraded di-isoctyl phthalate" that was used as a Plasticizer on the Sheath. I used to work on Crossbar systems in the 1980's and haven't seen it on relays but like you say its past its sell by date.

You've received a lot of solid advice from others, so I'll be the one to make it silly. Is there any chance it could be Flubber? Have you tried balling it up to see if it will bounce? If not, you may need to call The Ghostbusters.

Strowger had no goo. We had jelly filled cables though. We got paid more for handling them :-)

The potting material has degraded to the point where it is oozing out. The bad part is that potting material probably contains some pretty nasty chemicals. Since they were designed in the 1960's, you could be looking at PCBs, or other nasty chemicals used as insulator material. I wonder if Acetone, Mineral Spirits, or paint thinner would be the solvents needed to dissolve it out of the relay. The bad part is, would those solvents also damage the relay insulation on its coil. Brake cleaner might be a better solvent, since it evaporates quickly. I'm assuming you guys cannot get replacement sealed relays. :/ Once enough of that potting insulation oozes out, the life of the sealed relays is a ticking down clock. Thankfully, your frames aren't in a production setting. (where they're still used for calls) the open relays remind me of the relay switch setups in pinball machines.

I would not touch that stuff with bare hands. While it's not brown, the fact there was also a strange yellow substance might mean it contains PCBs, which were often used as insulation in capacitors and transformers.

That goo is like a green version of “icky PIC” moisture displacement compound from the inside of cables. I don’t know what the stuff is, but Western Electric sure succeeded in making the most tenacious obnoxious compound I know. There’s d-gel and some of my friends recommend De-Solv It for icky PIC removal. I’ve used De-solv It for removing tape reel and disk labels to good effect.

Perhaps try an ultrasonic cleaner and distilled water. You can try small additions of alcohol or vinegar. Vinegar would require at least two good rinses. Alcohol would be good even in rinses as it will allow more water to flow off the device.

How feasible is it to design functional plug- and logic-compatible new parts which use solid-state parts instead on a small custom PCB which would fit in the same footprint? E.g. Fetrons - plug compatible replacements for vacuum tubes.

I bet you that Acetone makes short work of the green goo of death.

I love how detailed you go with your explanation but I have a question... Moving to VOIP? lol

@6:20 my brain is hearing "Chitty, Chitty bang bang, chitty chitty bang bang..." And then I broke out into song for obvious reasons. 😂

Can you provide a flow chart or block diagram of this system? Where does the brain reside? No u processor.

As someone who works around old mechanical machines some dating back to 1940, I can agree, you just know from being around it and how it “talks” to you.

"Goop bad!" Hahaha! This is brilliant. Where can one buy that Hackers t-shirt btw? I'd quite fancy one myself :D

Sound in tech from the 1960's and before is always going to be one of your first indicators of a problem. I know several soldiers from the 1980's who were working in microwave relay trucks supporting Tropo Scatter radio systems who would often sleep in their rig's simply because it was going to be warmer than the tent on that hilltop in the middle of winter. Universally those who experienced a failure of a transmitter that happened while they were asleep, reported that the first indication that they had that there was a problem was not the transmitter shutting down, or fans failing (the equipment had a lot of high flow fans, which were as loud then as the cooling system for a crypto-mining hut are today.) No, the thing that woke them up was the relay for the alarm circuit for the radio detecting a problem ticking over. The next should that would be generated was the horn that you would expect would wake anyone in the rig, but as I say, every one who was asleep when one of these things tripped reported that the noise that woke them was t he relay click. They were wide awake before they heard the horn. If you were awake, then the only thing you 'heard' was the horn, but when you're sleeping, your subconscious filters out the steady noise better than any pair of sound canceling headphones ever will. That said, if you're in a room of teletypes, or relay operated equipment like a phone system, the noise of the mechanical bitss will tell the experienced operator if the equipment is healthy and happy, or not. I have thoughts on why these relays were potted, but no experience, so I'll shut up now and listen. :-)

Hmm, looks like you need a Western Electric part number, KS-DRIP-PAN under each row of leaking relays...

First I would analyze what the goo is. Mercury wetted relays normally don't leak anything. I would consider warming the relays and put them in a vacuum to encourage the goo to come out in a controlled way. The goo may be uncured potting material.

Awesome pics! I really love watching these videos and learning more about how these telephone switches work. It’s an interest I’ve had for a long time. Thank you for the video! Also, deep respect for your skills and tenacity, all of you!

19:00 it's the same with bowling pinsetters. I could tell from across the building if a machine was acting up just by the way it sounded.

1. Agree with brake clean and crc products 2. I can smell the museum source: working on aged electronics in the chemistry department at a major university.

I wonder if you can fit Pig Mats underneath it to soak it up before it leaks. I would be worried about that stuff leaking on me if there was mercury in it I would wear gloves

That "goo" is nasty stuff. I probably would not be touching it given the age of the equipment. It is quite possible it contains some pretty nasty chemicals, could even be a cancer causing chemical in it......... Can you disassemble to leaky relays and clean them and reseal them? Not sure what the goo actually is. I have seen similar stuff on some plastics used on cabling where the plastic has started to break down and leak a blue/green goo.

Where do you acquire working 316 relays today? How do you replace other relays if they break? Love learning about the old frames!

just started getting this channel in my suggestions i think because of networking/switching IT stuff. the videos are facinating.... i am noticing a niche aspect tho... um... not sure what..