As a phone company employee who spends at least some time in the CO, I can neither confirm nor deny that, given sufficient time, sounds in the CO, to include clicks, hums, fans and other sounds, when combined with comfortable temperatures, will eventually render the listener unconscious, especially if said listener has been tramping through the snow all night trying to find a broken interoffice fiber.
I like this kind of video. I am always impressed at the folks at Bell Labs and Western Electric in being able to not just design the complex system but also how to incorporate the trouble shooting systems. I'd like to see more like this.
Hi, Sarah. I don’t comment on videos often, but I LOVE your videos. I’m an IT VP who started my career in telecom and am an avid collector of old switches and phones.
Hi Sarah - I thoroughly enjoyed this video. I worked for Bell of Pa (hired in 1965 and retired in 2003). I was an associate from 1965 to 1969 and was trained in XBT and #5XBAR. Those wonderful call completion sounds brought back many memories as did the detatched schematics, sequence charts, etc. For the next 10 years I worked in staff on the #2 / 2BESS. I provided both over-the-phone and on-site support on many switchers, worked with BTL on software issues, fixed a lot of stuff and made a lot of friends. Thanks for taking me back to a time in my life that I really enjoyed. I intend to explore more of your videos!
This brings so many memories. I worked SXS local and SxS Cama which was a common control system so to speak. It had 8 senders, 4 transverters, 4 recorders with the perforated paper tape machines. Also worked Ani b & c systems. The office was a class 4 toll and class 5 local facility. I loved reading the detached and sequence prints to troubleshoot the the Cama system. It provided for some 14 cdo's which were SxS around the lake of the Ozarks area in Central Missouri centered at Eldon, Mo. I never worked crossbar per sa, but our Cama system had incoming registers and links which were 100 point crossbar switches. Also worked on the toll switchboard occasionally. Such cool stuff wished I could work it again. If I ever get to Seattle, I gotta see this. This is your best video yet. Thank you so much for your video. It has been very enjoyable.
We had a lake lot served by Sunrise Beach, and any long-distance calls to the locality came up Gravois Mills.. my parents were too cheap to put a phone line in, so we had to bug the retired neighbors.. it was weird how Eldon wasn't local, IIRC, but it was our link to the world... I still remember how MFs sounded calling there, it was the late 70s they had dial at the neighbors but we had a touch-tone... I never knew until after I left working for the phone company what those MF tones meant, and how fast they went, yet to find a crossbar that could save and process a call lickety-split. There were some calls you heard MF multiple times... Then as a kid, I sat down with a Kansas City phone book, back then local calls on either side of the state line were protected, and no duplicate issued central office codes unless you dialed 1 for in your area code, plus 7 digits or all 11 for another area code, but anyways, I found published pager numbers, which intrigued me, you heard the clickety-click ratchety sound of RP, I don't recall if the call went through GR, BA, or what downtown CO it went via.. for what I remember it could have been a 47X exchange, mom worked at a few places assigned it... In retrospect we never appreciated local calling as we should have, One vintage of a switch could call another and know how to pass the call along... What puzzled me was one of our residences was served in a building with the same rate center but two dissimilar office codes, ones that also were numerically adjacent to others in the local calling area.. for example, 796 could call 257 served in the same building, but 256 might be more-so downtown Independence served, it knew whether to call out for tandem or trunk vs same building and could sort it out. Then we moved to Blue Springs, the first 3 digits were assigned based on if you were toll to/from the center zone, when I was old enough for my line, it wasn't asked, but was given the same as my parents used, by this time 228 and 229 were both now local throughout the calling area, not one is and the other isn't.. then it came time for a number change, we had to stay on the same office code even after 1AESS was in use there.. we found a exploit to have three users all with call waiting become a 3-way call without the paid service or operator involvement. And to think I can't talk "phones" of yesterday with my roommate, he says his concern is, does it work or not.. Both Sarah and SxSPhil have places I'd love to visit. One of my school was served by XY and it was long removed before I knew how it worked, United had many of them, many of their offices had a couple of thousands levels assigned if that, but that honking busy..memories.. Time for me to hang up.. NyTol.
@@Stache987 I may know you. I worked southwestern bell 1973 until 1982 when I transferred to at&t long lines. I worked the sunrise Beach cdo for about 4 years then the Eldon told center about 5 years. I'm Ted Fox. Yes I would absolutely love to visit the see Seattle's connection museum and sxs Phil's switching systems.
@t13 fox most likely not, I was a "sheltered" kid, my first telco I worked for was Verizon landline. I live in a Central Iowa Podunk town where we have a co-op for a joke of a phone company, it's service area is so worthless unless you just put in a line for incoming calls, you cam call about 2500 lines toll free aside from the overbuild in colocated exchanges with dedicated prefixes. Although I would like to meet up with people who could talk "phone" at leisure.
"I know that this video isn't like the super high production value stuff that I've been putting out.." No, but it's still one of the BEST videos BECAUSE it is real life troubleshooting stuff that I very much enjoy watching. Of course I don't wish for you to have more trouble, but when you do, please record 🙂
Keeping a cool head, going over possible faults, going back on initial thoughts and finding a solution. AND to be able to explain the process in a clear way. Thanks Sarah. Great video!
👋 Sarah. ;) Great to see another video. Thank you for taking us along on the journey through the machine. I think the best way to learn how things work is to have to fix them. :D
Thanks to to my mom who retired for ole Ma Bell, I fully understand everything you're talking about. She actually worked with almost every version of the older electro-mechanical systems. She retired out just as they were switching over to comp controls
I enjoyed this. It shows how you were able to determine that there was a bad solder on a wire. It also shows that you need to be analytical. Some people would never be good at hunting for this stuff even after 20 years. You’re a professional analyst.
Well done! Again an interesting video. In the UK there is so much Strowger and the trouble shooting was quite different because your superb problem reporting system and circuits were not implemented. Thanks, and don’t worry about production quality, it’s the content that matters in your videos 😉👍.
More real time troubleshooting!! Built a small town dial up ISP back in the day. Fascinating to see whats happening in the CO behind the scenes. Thanks Sarah, subbed!
I'd like to say thanks for showing troubleshooting. I've been so lazy in describing all the knowledge that goes along with what seems like a simple thing a person could do but that the average person just doesn't understand. I kept yelling at a client that I know what is missing and that if I see X then it means that Y must be fine but I also expect Z but am not seeing it. That means I could expect C but they just can't grasp it. You've created a wonderful tool showing in real time what I don't have the patience for.
UA-cam just keeps on getting exponentially better and better. You got to have Lily Tomlin that played Ernestine on Rowan and Martin's Laugh In hour, on one of your episodes. _One ringy dingy, two ringy dingy, three ringy dingy._
Hi Sarah. I think I've sadly come to the conclusion that as much as I would like to understand a lot of the details of switching, a lot of it is well over my head and probably always will be. But even not fully understanding exactly what everything does and what the specific path is, I find the troubleshooting process fascinating. Figuring out how to replicate the problem, coming up with theories as to what could be wrong, testing them, etc. It's great seeing that play out in real time, and not just as updates after the fact. Also, I visited the museum a couple of weeks ago, said hi, and follow around on a late tour. Thanks again.
Probably the most enjoyable video you have made. I was riveted to the end. It always sounds funny to an English person the way people there say sodder rather than solder 😉. You are a star, thanks.
Excellent job troubleshooting, and going through each step. You are a skilled technician, Sarah. I'd love someday to come your your switch room and see your lovely displays. Thanks, and be well!
32:51 Point taken. It took me about 25 years to get really good at my thing. Fixing video recorders in my case. I wouldn't have a clue where to start in an old telephone exchange.
I love long format videos that are just loaded with technical content. I wish this video could have just gone on and on. I'll have to watch it again and again to compensate. 😄
@@jd3497 They were in service, sure, but then all of the interframe wires were cut, and the frames were trucked to the museum. Then a bunch of old guys soldered them back together between coffee, donuts, and lunch break! (Wire wrap didn't exist in 1942.)
I worked panel, #1xb, tandem, #5xb,#1ess,#5ess, and EWSD, plus power plants in my 42 year carrier. POOF, all gone now. Good to see the history saved. JJ
The view from your window is a stereotype of a rainy San Francisco day. Thanks for walking me through your troubleshooting technique, the telephone switch schematics are totally different than what I'm used to in the electronics industry but they make sense to me in a perverse sort of way. You certainly have a nice workplace.
What would the result of this bad solder joint be from a customers perspective, or would they notice a problem at all? Would this be affecting the dialing party or the dialed party? I love being able to eek out a problem step by step, using flowcharts, ladder diagrams, wiring diagrams, and field testing and troubleshooting. I work in the low voltage security industry and when I'm troubleshooting a problem I always start by asking myself 'what is the system supposed to do? what is it doing instead?, when did it fail and what was it doing when it failed?' Often times I'll look at the last recorded video if it's a camera problem and watch as a lightning storm rolls through, or a camera turns in to a fishbowl from a water leak somewhere.
I love how you are able to break all of this down, but I have one question: how would the troubleshooting be different on a 'real' system? I would imagine other calls would interfere with your troubleshooting measurements and also vice versa. Is this a place where a real exchange would have multiple copies of this circuitry so you could isolate the one under question?
Good question. In the museum we have just one of each frame--one Originating Marker, one District Link, and so on. In a real working office, you'd have several of everything, and the load is distributed evenly. The first step in troubleshooting is to "busy out" the effected equipment to take it out of service so you can troubleshoot it. The remaining frames will take up the load during that time. In the museum, I don't bother busying anything out, because there's no point. There isn't any remaining equipment to take up the load. The only case where I will do this is for a specific trunk, or a specific sender--those can be busied out because there are several of each on a frame. In real life, there are some frames that you just can't busy out, regardless of how many you have. An example of this is the line link frame, and the number group connector. On those frames, each piece of equipment corresponds 1-1 with a subscriber's line, so you can't take them out of service because it would deny customers access. In those cases, you can try to busy out only a small portion of the frame to have the least impact possible. In addition, the control circuits on those frames are "mated", so in the case of an emergency, a controller from an adjacent frame can take up the load, even though it would not normally handle that load.
Love this video. Lots of cool things shown here. Is there a video or a plan for those of you who volunteer there and how long you've been doing it, what got you into it, what keeps you volunteering etc?
F - Test jack. Lets me plug the remote control into the test frame and execute tests without having to physically be at the test frame. A - 48V/GND supply for whatever equipment I'm using in the aisle. Lamp, test cart, anything. B - Belt line. Just a pair of wires that runs to every single frame in the entire office and I can plug whatever I want into whatever else. I usually use it as a telephone line and plug the other end into a particular dial tone appearance on the line link. TEL - Telephone. I can plug a headset in there and talk to anyone else in the building. All other frames have a similar pair of jacks for a headset, and anyone plugged in there is on the same building-wide talk circuit. No dialing, just talking. HRG - High Resistance Ground. Ground through a resistor so I can test things without blowing fuses.
It's going to take me a while to get through all of this, but I always longed to know how a crossbar switch worked. One question I have is, in the actual matrix, where a row gets connected to a column, is there a separate relay at each point? Or do I understand that there's a finger on a metal rod that can slide up and down, and make or break the connection between any row and that column, so that the whole affair has fewer moving parts?
There's a video about the crossbar switch. There isn't a separate magnet at each point, but there's a separate set of contacts a point. The row and column magnets mechanically jam them closed as long as the column is held active, if the row was active at the moment the column was activated. This is accomplished with the fingers loosely attached to the row bar, and the column bar jams them in their current position.
We do have the schoolbooks though. I learned from the same textbooks they learned from--but it would have been nice to have a teacher and a classroom :)
It seems that everything electrical is subject to a bad solder joint, transistor radio to modern computer. At least back then we were allowed to use lead based solder.
Sarah - Hi thanks for making a new video I enjoy the videos with you walking around the whole switch it's just super interesting. If you were at a desk we couldn't understand what your talking about I'm visual learner. How many phone numbers would this effect? Would this punch a card too? or is this a different switch? thank you Hope to see you soon new a video
Thank you :) The card punch is a different switch. In this one, it just lights lamps instead of punching a card. A number group frame serves 800 lines, and one in each block of 20 would be impacted by this problem. So if we do 800/20, we get 40 telephone numbers would have been impacted by this problem
After I was all done I saw the video for the card punch machine that is on the 5XB switch. I wish I could visit maybe one day! Take care and Happy Holidays Sarah
It there some kind of device that alerts you of fail indicator lamps? It'd be a shame to go through a bunch of troubleshooting only to realize that a burned out bulb has sent you on a wild goose chase
Sadly, no. If they fail, you just have to know about it. We’ve all gone on at least one wild goose chase. Then we learned to “trust, but verify”. If the lamps are saying something that’s nonsense (imagine a sentence that is missing a word) it’s usually time to get suspicious.
I extremely like the background noises. Would be nice if you can make a separate Video with only the Background Machine Noises :D i really would like to work at this nice place. I currently work at a Telecommunications Company but we have only more or less Modernized stuff. But i like the real old stuff more :D
It's like watching someone practicing an ancient language spoken only by 13 people left on earth that understand it. Who will carry this work on a few decades from now, or will it, one day, stop working, because those 13 have all died? And then you might as well just shut off the power like one of those 10" diameter steel shafts I saw once in a museum that used to turn the parts of a purely mechanical computer; it will never rotate again, because the display was only a piece of a giant computer that was cut up and is no more.
Great video! I know I could Google my question but likely will get 50% flat out fake answers so if you kindly would explain, when you have a sec in your own words, having been exposed to the secrets of this tech for so long: what's the point of the power source architecture of -48v, ground and +48v? Is 96v ever used anywhere? Why do it that way? I know in op amps and comparators the reason for the split supply but in the world of mechanical relays? Thanks a bunch!
96v is not used anywhere. It's only - 48V referenced to ground in analog telephone work. (+/- 130V is used in carrier circuits, and -24V is used in local manual circuits, but thats a different question). The reason for using -48V is to prevent electrolysis from occurring in buried cables outside. Telephone companies spent a lot of money on outside wiring, and soon discovered that if the cable voltage was positive relative to ground, that electrolysis would occur and slowly eat away at the wire, leaving the cables useless. By keeping the wires negative in reference to ground, electrolysis doesn't occur, and all of that money that they spent on cable wouldn't be wasted. There's no other reason for using negative voltage in relay circuits. The relays themselves don't care which way the electrons are moving---unless they're polar relays :)
I spy on your walking tour between relay racks a National receiver and a Burd-43 watt meter must be some amateurs around the museum besides Sarah the professional wire chief.
Sarah @connections museum Have you ever thot of connecting a voip fxs ata adapter to your phone system in the museum as a incoming trunk and a fxo ata adapter as an outgoing trunk so that people from outside of the museum can see how the old phone systems worked and how you can connect extremely old equipment with modern day equipment
@Michael Wallace1092 I downloaded it, created a username but keep getting a use it or lose it email monthly or so otherwise that's the most I know of it
"Ground is getting here. I'm positive of that." In a telephone exchange, this is doubly true.
I could listen to the ambiance of that room all day. I love how the room sounds with the periodic clicking of the switch.
You know, that would be a excellent idea for this channel. An ASMR 1 hour or 10 hour looped video of just the sounds of the switching room.
@@browningchannel Oh totally! Next time I'm allowed/able to travel to the US, I'll bring a high-quality stereo audio recording setup!
same, I could listen to the noises all day too.
As a phone company employee who spends at least some time in the CO, I can neither confirm nor deny that, given sufficient time, sounds in the CO, to include clicks, hums, fans and other sounds, when combined with comfortable temperatures, will eventually render the listener unconscious, especially if said listener has been tramping through the snow all night trying to find a broken interoffice fiber.
It would be good sound to sleep to
I like this kind of video. I am always impressed at the folks at Bell Labs and Western Electric in being able to not just design the complex system but also how to incorporate the trouble shooting systems. I'd like to see more like this.
Hi, Sarah. I don’t comment on videos often, but I LOVE your videos. I’m an IT VP who started my career in telecom and am an avid collector of old switches and phones.
Hi Sarah - I thoroughly enjoyed this video. I worked for Bell of Pa (hired in 1965 and retired in 2003). I was an associate from 1965 to 1969 and was trained in XBT and #5XBAR. Those wonderful call completion sounds brought back many memories as did the detatched schematics, sequence charts, etc. For the next 10 years I worked in staff on the #2 / 2BESS. I provided both over-the-phone and on-site support on many switchers, worked with BTL on software issues, fixed a lot of stuff and made a lot of friends. Thanks for taking me back to a time in my life that I really enjoyed. I intend to explore more of your videos!
This brings so many memories. I worked SXS local and SxS Cama which was a common control system so to speak. It had 8 senders, 4 transverters, 4 recorders with the perforated paper tape machines. Also worked Ani b & c systems. The office was a class 4 toll and class 5 local facility. I loved reading the detached and sequence prints to troubleshoot the the Cama system. It provided for some 14 cdo's which were SxS around the lake of the Ozarks area in Central Missouri centered at Eldon, Mo. I never worked crossbar per sa, but our Cama system had incoming registers and links which were 100 point crossbar switches. Also worked on the toll switchboard occasionally. Such cool stuff wished I could work it again. If I ever get to Seattle, I gotta see this. This is your best video yet. Thank you so much for your video. It has been very enjoyable.
We had a lake lot served by Sunrise Beach, and any long-distance calls to the locality came up Gravois Mills.. my parents were too cheap to put a phone line in, so we had to bug the retired neighbors.. it was weird how Eldon wasn't local, IIRC, but it was our link to the world... I still remember how MFs sounded calling there, it was the late 70s they had dial at the neighbors but we had a touch-tone... I never knew until after I left working for the phone company what those MF tones meant, and how fast they went, yet to find a crossbar that could save and process a call lickety-split. There were some calls you heard MF multiple times...
Then as a kid, I sat down with a Kansas City phone book, back then local calls on either side of the state line were protected, and no duplicate issued central office codes unless you dialed 1 for in your area code, plus 7 digits or all 11 for another area code, but anyways, I found published pager numbers, which intrigued me, you heard the clickety-click ratchety sound of RP, I don't recall if the call went through GR, BA, or what downtown CO it went via.. for what I remember it could have been a 47X exchange, mom worked at a few places assigned it...
In retrospect we never appreciated local calling as we should have, One vintage of a switch could call another and know how to pass the call along...
What puzzled me was one of our residences was served in a building with the same rate center but two dissimilar office codes, ones that also were numerically adjacent to others in the local calling area.. for example, 796 could call 257 served in the same building, but 256 might be more-so downtown Independence served, it knew whether to call out for tandem or trunk vs same building and could sort it out. Then we moved to Blue Springs, the first 3 digits were assigned based on if you were toll to/from the center zone, when I was old enough for my line, it wasn't asked, but was given the same as my parents used, by this time 228 and 229 were both now local throughout the calling area, not one is and the other isn't.. then it came time for a number change, we had to stay on the same office code even after 1AESS was in use there.. we found a exploit to have three users all with call waiting become a 3-way call without the paid service or operator involvement.
And to think I can't talk "phones" of yesterday with my roommate, he says his concern is, does it work or not..
Both Sarah and SxSPhil have places I'd love to visit. One of my school was served by XY and it was long removed before I knew how it worked, United had many of them, many of their offices had a couple of thousands levels assigned if that, but that honking busy..memories..
Time for me to hang up.. NyTol.
@@Stache987 I may know you. I worked southwestern bell 1973 until 1982 when I transferred to at&t long lines. I worked the sunrise Beach cdo for about 4 years then the Eldon told center about 5 years. I'm Ted Fox. Yes I would absolutely love to visit the see Seattle's connection museum and sxs Phil's switching systems.
@t13 fox most likely not, I was a "sheltered" kid, my first telco I worked for was Verizon landline. I live in a Central Iowa Podunk town where we have a co-op for a joke of a phone company, it's service area is so worthless unless you just put in a line for incoming calls, you cam call about 2500 lines toll free aside from the overbuild in colocated exchanges with dedicated prefixes. Although I would like to meet up with people who could talk "phone" at leisure.
@@Stache987 well, at least we've worked similar careers.
@@Stache987 yes, we could talk anytime. It would be great.
"I know that this video isn't like the super high production value stuff that I've been putting out.."
No, but it's still one of the BEST videos BECAUSE it is real life troubleshooting stuff that I very much enjoy watching. Of course I don't wish for you to have more trouble, but when you do, please record 🙂
Keeping a cool head, going over possible faults, going back on initial thoughts and finding a solution. AND to be able to explain the process in a clear way. Thanks Sarah. Great video!
It's a wonder she has not needed wigs for all the hair she would have pulled out had she not tolerated it.
👋 Sarah. ;) Great to see another video. Thank you for taking us along on the journey through the machine. I think the best way to learn how things work is to have to fix them. :D
Hi Piotr! ❤ I agree completely. The only way I can learn about anything is to fix it. :)
I really enjoyed this video. It was definitely not low effort. Watching the troubleshooting process is very interesting (to me, at least).
Thanks to to my mom who retired for ole Ma Bell, I fully understand everything you're talking about. She actually worked with almost every version of the older electro-mechanical systems. She retired out just as they were switching over to comp controls
I regret never going to work with her for my first job, I would've been in heaven with all this tech
I enjoyed this. It shows how you were able to determine that there was a bad solder on a wire. It also shows that you need to be analytical. Some people would never be good at hunting for this stuff even after 20 years. You’re a professional analyst.
Ace Troubleshooter
Well done! Again an interesting video. In the UK there is so much Strowger and the trouble shooting was quite different because your superb problem reporting system and circuits were not implemented. Thanks, and don’t worry about production quality, it’s the content that matters in your videos 😉👍.
More real time troubleshooting!! Built a small town dial up ISP back in the day. Fascinating to see whats happening in the CO behind the scenes. Thanks Sarah, subbed!
I want to visit this place! it looks so friggin rad!
Great bug hunting, well found and resolved, thanks for taking us with you :-)
I'd like to say thanks for showing troubleshooting. I've been so lazy in describing all the knowledge that goes along with what seems like a simple thing a person could do but that the average person just doesn't understand. I kept yelling at a client that I know what is missing and that if I see X then it means that Y must be fine but I also expect Z but am not seeing it. That means I could expect C but they just can't grasp it. You've created a wonderful tool showing in real time what I don't have the patience for.
Great work. I caught the tail-end of these systems before upgrade to TXE4 TXE10 (UK) thereafter, fault finding was never the same.
UA-cam just keeps on getting exponentially better and better.
You got to have Lily Tomlin that played Ernestine on Rowan and Martin's Laugh In hour, on one of your episodes.
_One ringy dingy, two ringy dingy, three ringy dingy._
Hi Sarah. I think I've sadly come to the conclusion that as much as I would like to understand a lot of the details of switching, a lot of it is well over my head and probably always will be. But even not fully understanding exactly what everything does and what the specific path is, I find the troubleshooting process fascinating. Figuring out how to replicate the problem, coming up with theories as to what could be wrong, testing them, etc. It's great seeing that play out in real time, and not just as updates after the fact.
Also, I visited the museum a couple of weeks ago, said hi, and follow around on a late tour. Thanks again.
Probably the most enjoyable video you have made. I was riveted to the end. It always sounds funny to an English person the way people there say sodder rather than solder 😉. You are a star, thanks.
Great video, Sarah! Thanks for the walkthrough on troubleshooting.
I really enjoy listening to you problem solve.
Neat. Thanks for the trouble-shooting tour. Please do more of this as your able.
Excellent job troubleshooting, and going through each step. You are a skilled technician, Sarah.
I'd love someday to come your your switch room and see your lovely displays. Thanks, and be well!
32:51 Point taken. It took me about 25 years to get really good at my thing. Fixing video recorders in my case. I wouldn't have a clue where to start in an old telephone exchange.
I love long format videos that are just loaded with technical content. I wish this video could have just gone on and on. I'll have to watch it again and again to compensate. 😄
Ah shit, it's those cold joints again! You do a wonderful job troubleshooting such a complex system :)
How could this equipment have had a bad solder joint all these years? Weren't these frames in service in a CO? Why solder and not wire wrap?
@@jd3497 They were in service, sure, but then all of the interframe wires were cut, and the frames were trucked to the museum. Then a bunch of old guys soldered them back together between coffee, donuts, and lunch break! (Wire wrap didn't exist in 1942.)
I worked panel, #1xb, tandem, #5xb,#1ess,#5ess, and EWSD, plus power plants in my 42 year carrier. POOF, all gone now. Good to see the history saved. JJ
The view from your window is a stereotype of a rainy San Francisco day.
Thanks for walking me through your troubleshooting technique, the telephone switch schematics are totally different than what I'm used to in the electronics industry but they make sense to me in a perverse sort of way. You certainly have a nice workplace.
I'm also a telephone electromechanical maniac. So interesting to see your logic analysis in your videos which are music to my eyes and ears.
What would the result of this bad solder joint be from a customers perspective, or would they notice a problem at all? Would this be affecting the dialing party or the dialed party? I love being able to eek out a problem step by step, using flowcharts, ladder diagrams, wiring diagrams, and field testing and troubleshooting. I work in the low voltage security industry and when I'm troubleshooting a problem I always start by asking myself 'what is the system supposed to do? what is it doing instead?, when did it fail and what was it doing when it failed?' Often times I'll look at the last recorded video if it's a camera problem and watch as a lightning storm rolls through, or a camera turns in to a fishbowl from a water leak somewhere.
It sounds like the call wouldn't go through. It would get stuck OR it would go to an error signal, like busy.
I love how you are able to break all of this down, but I have one question: how would the troubleshooting be different on a 'real' system? I would imagine other calls would interfere with your troubleshooting measurements and also vice versa. Is this a place where a real exchange would have multiple copies of this circuitry so you could isolate the one under question?
Good question. In the museum we have just one of each frame--one Originating Marker, one District Link, and so on. In a real working office, you'd have several of everything, and the load is distributed evenly. The first step in troubleshooting is to "busy out" the effected equipment to take it out of service so you can troubleshoot it. The remaining frames will take up the load during that time.
In the museum, I don't bother busying anything out, because there's no point. There isn't any remaining equipment to take up the load. The only case where I will do this is for a specific trunk, or a specific sender--those can be busied out because there are several of each on a frame.
In real life, there are some frames that you just can't busy out, regardless of how many you have. An example of this is the line link frame, and the number group connector. On those frames, each piece of equipment corresponds 1-1 with a subscriber's line, so you can't take them out of service because it would deny customers access. In those cases, you can try to busy out only a small portion of the frame to have the least impact possible. In addition, the control circuits on those frames are "mated", so in the case of an emergency, a controller from an adjacent frame can take up the load, even though it would not normally handle that load.
Love this ! Good thing they made good documentation on this !
Gotta get back to that CO again soon !
Another good one!, I really enjoy learning how all the phone system works, very cool. Thank you so much for this video!!
Wicked cool stuff! Thanks for sharing all this!
"Somewhere in this entire machine" fav quote
13:06 so if I ring one of the phones while the switches are on, someone actually answers?
EDIT: Confirmed! They are happy to answer questions.
Love this video. Lots of cool things shown here. Is there a video or a plan for those of you who volunteer there and how long you've been doing it, what got you into it, what keeps you volunteering etc?
What are the jacks at 24:25? (48V and GND are self-explanatory..., curious about the others)
F - Test jack. Lets me plug the remote control into the test frame and execute tests without having to physically be at the test frame.
A - 48V/GND supply for whatever equipment I'm using in the aisle. Lamp, test cart, anything.
B - Belt line. Just a pair of wires that runs to every single frame in the entire office and I can plug whatever I want into whatever else. I usually use it as a telephone line and plug the other end into a particular dial tone appearance on the line link.
TEL - Telephone. I can plug a headset in there and talk to anyone else in the building. All other frames have a similar pair of jacks for a headset, and anyone plugged in there is on the same building-wide talk circuit. No dialing, just talking.
HRG - High Resistance Ground. Ground through a resistor so I can test things without blowing fuses.
@@ConnectionsMuseum belt line is a great idea for them to include
Love your videos Sarah i look forward to seeing your new videos i hope someday I can take a tour of your awesome museum
It's going to take me a while to get through all of this, but I always longed to know how a crossbar switch worked. One question I have is, in the actual matrix, where a row gets connected to a column, is there a separate relay at each point? Or do I understand that there's a finger on a metal rod that can slide up and down, and make or break the connection between any row and that column, so that the whole affair has fewer moving parts?
There's a video about the crossbar switch. There isn't a separate magnet at each point, but there's a separate set of contacts a point. The row and column magnets mechanically jam them closed as long as the column is held active, if the row was active at the moment the column was activated. This is accomplished with the fingers loosely attached to the row bar, and the column bar jams them in their current position.
You are a treasure! Such dedication.
Love the videos! Keep them coming!!
24:01 I said aloud, "REALLY?!" Three seconds later, she says, "Not really." "Awwwwwwwwwwwwwwwwwwwwwwwwwwwwwww"
We do have the schoolbooks though. I learned from the same textbooks they learned from--but it would have been nice to have a teacher and a classroom :)
Excellent troubleshooting
Just found your videos, looking forward to watching the rest.
Screw production values. This video was cool
Your living room looks cozy. The perfect place to talk about phone switching :)
Where did you learned all this stuff? This is amazing :D I am addicted to your videos.
It seems that everything electrical is subject to a bad solder joint, transistor radio to modern computer. At least back then we were allowed to use lead based solder.
I just fixed a bunch of black magic video gear with - yep, you guessed it - poor/cold solder joints in the power supply.
Sarah - Hi thanks for making a new video I enjoy the videos with you walking around the whole switch it's just super interesting. If you were at a desk we couldn't understand what your talking about I'm visual learner. How many phone numbers would this effect? Would this punch a card too? or is this a different switch? thank you Hope to see you soon new a video
Thank you :) The card punch is a different switch. In this one, it just lights lamps instead of punching a card.
A number group frame serves 800 lines, and one in each block of 20 would be impacted by this problem. So if we do 800/20, we get 40 telephone numbers would have been impacted by this problem
After I was all done I saw the video for the card punch machine that is on the 5XB switch. I wish I could visit maybe one day! Take care and Happy Holidays Sarah
Every time u do this it amazes me.
I love what you're doing.
Just a great vid, thanks!
That phone ringing at 13~ min freaked me out! I had a flash back of the MATRIX LET ME OUT
Hanging out is cool 😌
Very interesting, I have had to trouble shoot like that on 2BESS, brings back memories.
A mn educational and entertaining troubleshooting session. Very much enjoying your presentations
Very enjoyable.Thanks
I tel, ya what, I love me a gal who knows her way around a SXS system. It's also fascinating seeing the troubleshooting process!
13:00 lol what happened there?
35:57 damage sound effect
Much easier to see call flow in an electromechanical switch compared to an i3 ESInet sip 9-1-1 call with pidflo. 😀
So they are groups of 18 and 3/4 ?
"I already know where it is" :)
Nice. What’s your name?
It there some kind of device that alerts you of fail indicator lamps? It'd be a shame to go through a bunch of troubleshooting only to realize that a burned out bulb has sent you on a wild goose chase
Sadly, no. If they fail, you just have to know about it. We’ve all gone on at least one wild goose chase. Then we learned to “trust, but verify”.
If the lamps are saying something that’s nonsense (imagine a sentence that is missing a word) it’s usually time to get suspicious.
I extremely like the background noises. Would be nice if you can make a separate Video with only the Background Machine Noises :D i really would like to work at this nice place. I currently work at a Telecommunications Company but we have only more or less Modernized stuff. But i like the real old stuff more :D
I've been looking for damage with a 60V 50mA bulb based probe, it's much more convenient. Our telephone stations work from -60V
And, now I know why the switchmen would walk around with a headset around their neck! Never realized they were using it for tracing grounds.
What I don't understand are these real calls or fake calls
It's like watching someone practicing an ancient language spoken only by 13 people left on earth that understand it. Who will carry this work on a few decades from now, or will it, one day, stop working, because those 13 have all died? And then you might as well just shut off the power like one of those 10" diameter steel shafts I saw once in a museum that used to turn the parts of a purely mechanical computer; it will never rotate again, because the display was only a piece of a giant computer that was cut up and is no more.
This is a great " nerd out" video.... scripting is an option....
Wire wrap connections are more reliable than solder joints (per Bell Labs research)
Why don’t you cross train others in troubleshooting?
Actual no effort November
interesting though
Great video! I know I could Google my question but likely will get 50% flat out fake answers so if you kindly would explain, when you have a sec in your own words, having been exposed to the secrets of this tech for so long: what's the point of the power source architecture of -48v, ground and +48v? Is 96v ever used anywhere? Why do it that way? I know in op amps and comparators the reason for the split supply but in the world of mechanical relays? Thanks a bunch!
96v is not used anywhere. It's only - 48V referenced to ground in analog telephone work. (+/- 130V is used in carrier circuits, and -24V is used in local manual circuits, but thats a different question).
The reason for using -48V is to prevent electrolysis from occurring in buried cables outside. Telephone companies spent a lot of money on outside wiring, and soon discovered that if the cable voltage was positive relative to ground, that electrolysis would occur and slowly eat away at the wire, leaving the cables useless. By keeping the wires negative in reference to ground, electrolysis doesn't occur, and all of that money that they spent on cable wouldn't be wasted.
There's no other reason for using negative voltage in relay circuits. The relays themselves don't care which way the electrons are moving---unless they're polar relays :)
@@ConnectionsMuseum Thank you!
The NPSTN and Phreaknet DISAs are down. Just thought I would let you know
Sorry! There was a misconfiguration in the Phreaknet portal. NPSTN access will continue to not work.
I spy on your walking tour between relay racks a National receiver and a Burd-43 watt meter must be some amateurs around the museum besides Sarah the professional wire chief.
No idea why they put those there! A lot of the museum founders were hams, so our collection is full of radio equipment.
Sarah, you're so intelligent and pretty. You remind me of Mayim Bialik 😊
Sarah @connections museum Have you ever thot of connecting a voip fxs ata adapter to your phone system in the museum as a incoming trunk and a fxo ata adapter as an outgoing trunk so that people from outside of the museum can see how the old phone systems worked and how you can connect extremely old equipment with modern day equipment
Nice trouble shooting skills….. I am a maintenance electrician by trade
Coding with relays and wires!
I am addicted to your videos. Thank you.
On C*NET it said you were hooked to the museum at home, it'd since been de-listed, but are you THAT addicted to the MUSEUM?
@Michael Wallace1092 well, she's dedicated.. enough to sit down and drink black goo in tonight's video..
@Michael Wallace1092 I downloaded it, created a username but keep getting a use it or lose it email monthly or so otherwise that's the most I know of it
@Michael Wallace1092 I didn't forget you, if you were the one talking about lake of the Ozarks.. if you were help me get my discord up and we can chat