Continued from: Jobs I've Had - Telecom Australia (5) After completing the training in Sydney it was back to Sherwood EMG to begin a period of preforming maintenance work on the equipment I had spent months learning about, combined with connecting new telephone services, connecting special services for banks etc., and fault finding on these as well. This was the most enjoyable period of my 22 years with Telecom Australia. The telephone exchange equipment, known as an ARE-11 exchange, was fascinating to work on. Any time on any day I could be chasing obscure faults which could be physical wiring faults, worn out or poorly adjusted electro-mechanical relays, software faults in the processors which controlled the exchange, or hardware faults with the electronic components or circuit boards. The image above shows one suite of equipment, made up of multiple racks, and each rack could have multiple crossbar switches (glass covers), or multiple relay sets (grey metal covers). There is also a front and rear side to each rack. This is a subscriber stage which connected 1000 phone lines to others phone lines either within the same exchange or to junction circuits to other exchanges. If the exchange had 7000 phone lines connected to it there would be seven of these suites. In addition to that there were suites dedicated to incoming circuits from other exchanges, outgoing circuits to other exchanges, group switching stages, the processor control equipment, electronic interface equipment to link the processors with the relay-based technology, and more. As the image below shows with multiple suites needed for all the equipment, these telephone exchanges were quite big, and usually full of equipment. At the end of each suite of equipment there were coloured lights to show the status of the equipment in that suite. Red indicated a fault requiring urgent attention, yellow was a less urgent fault to attend to and white indicated some equipment was manually blocked out of service. There were also alarm bells for various urgent faults.
I hope these images build a picture of just how complex an ARE-11 (processor controlled crossbar) telephone exchange was. Literally thousands of relays, thousands of metres of cabling, hundreds of circuit boards and more... Despite this complexity I found it easy to locate faults when they occurred. I used to joke that a 'good technician' used all his senses when fault finding. You could listen to the exchange switching a call and hear at what point the call failed (generally speaking); you could see a badly adjusted relay when you removed the grey metal cover; you could smell a burnt out component like a resistor or capacitor; you could feel with your fingers a relay that was sticky and slow to operate. The only sense I could not incorporate was taste..!!
There were supplies of most spare parts at each exchange, sometimes you would have to travel to another exchange to find the right part, and failing that you would have to drive to the city and visit Hesketh House in Elizabeth Street where a larger pool of spare parts was held. We had to manage our own supplies of spare parts and re-order items when stock became low. Faulty circuit boards were sent away for repair and replaced with new items.
Faults occurred any time day or night and we were called out when required at night or on the weekend to attend to faults that could not wait, or that could not be remotely managed by the Brisbane After Hours Centre. Much of the exchange equipment was duplicated so that if a fault developed the suspect equipment could be blocked out to prevent telephone calls failing. Other times when exchange equipment failed it was a case of find the fault and fix it as soon as possible as every failed telephone call was a loss of revenue - that was when the pressure was on. I am pleased to say I always succeeded and it was satisfying quickly analyse the situation, change a part, then listen to the click of the relays and know by the sound alone that everything was returning to normal. Every now and then I would be at an exchange and the normal click of the relays would suddenly increase to a chaotic rate. This happened when radio stations had a quiz, or when concert tickets went on sale. There was a specific number range allocated to this (223 0xxx) and the telephone network was designed to handle this sudden surge in telephone calls without impacting regular phone calls. The problem was that some businesses just advertised regular phone numbers and with many hundreds or thousands of simultaneous calls to the same destination the entire exchange and telephone network would be thrown into massive congestion. My only regret was that this type of equipment was later phased out in preference to fully digital equipment which required far less maintenance. There was a strange fault that existed at Jamboree Heights in the 376 1xxx group prior to it being upgraded to digital, something that caused a massive but short-lived chatter of relays, but did not effect phone calls. I was somewhat progressed in identifying the cause when the equipment was decommissioned and changed over to digital. I never got to solve that mysterious fault - and I still think about it to this day..!!
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Continued from: Jobs I've Had - Telecom Australia (4) After completing my six months of field training at Sherwood EMG it was back to Chermside and the Telecom Australia Training School. If this phase I completed the common theory and practical courses, and started into job specific training. For the job specific courses I was sent to Hesketh House in Brisbane. This is probably not a building many have heard of and the entrance we used was actually through Telecommunications House which was at 283 Elizabeth Street - opposite Edison Telephone Exchange.
Hesketh House by the 1980's was owned by Telecom Australia and had some sections of the training branch located there. The job specific courses I attended were in the operation and maintenance of the crossbar telephone exchange equipment, which is what I had seen at Inala and Wacol. In fact a very large proportion of the entire Brisbane telephone network was at this time crossbar; the next generation equipment known as AXE was just entering the scene. The crossbar exchange equipment at Inala and the other four exchanges in the Sherwood EMG area connected the 27000 telephone lines for private customers and businesses in that area with the rest of Australia and the world. In the basement level of Hesketh House there was an entire 'model' exchange that apprentice technicians could work on, finding faults and learning the complexities of the equipment, without any interruption to public telephone calls. The photo below shows the back of some crossbar switches and hopefully gives a small sample of the complexity of the equipment and wiring involved. The crossbar telephone exchange was largely electro-mechanical in design, in other words, relays - and there were thousands of them each with a specific function and designation code. There were several courses to attend here as each section of the crossbar exchange was explained in great detail. The block diagram in Jobs I've Had - Telecom Australia (4) gives an idea of the complexity, and there were nine courses in total with each lasting at least a week and involving theory and practical training. We had to know how every section of the exchange worked:
That is putting it all very simply as even the first stage, the subscriber stage, had a number of steps to work through. Firstly the hundreds digit of the number making the call was identified, then the tens digit, then the units digit - this information, along with the thousands digit, was transferred to other equipment as the connection process continued. If two people lifted the handset to make a call at the same time the equipment would have to process one request first then the second. Considering the telephone lines were grouped into sections of 1000 phone lines, several people could lift the handset at the same time - the circuitry was designed to deal with each phone call in a fraction of a second so even if it was very busy the customer hardly noticed any delay. The final course was conducted in Sydney at the New South Wales Telecom Australia Training Centre at North Strathfield. This particular piece of equipment that apprentice technicians needed to work on and learn about only existed in Sydney so apprentices from all over Australia visited North Strathfield for this course. I decided to stay at Strathfield, near the railway station, and catch the train each day to North Strathfield where a short walk was all that was needed to get to the course venue. I stayed at the Strathfield Hotel, near the railway station and Strathfield Plaza shopping centre. The later place would become famous in August 1991 when a gunman killed 7 people and injured 6 more before killing himself. I had certainly walked through this shopping plaza on several occasions during my visit in the 1980's as it was just a three minute walk from where I was staying. To be continued..... Continued from: Jobs I've Had - Telecom Australia (3) The diagram below, which I will go into more detail another day, is a very basic diagram of an ARE-11 exchange. The top part above the dashed line is the original crossbar exchange with relays and electro-mechanical switches, the bottom part is the processor control and interfacing electronics which, in the case of Inala, was brand new in 1985 when I started working there. The ARE-11 system as the whole exchange type was known was implemented in Australia from 1976. The bottom left corner of the diagram has a box marked 'SCS' which stands for Subscriber Category Store. This was an electronic data store which held information about every phone number in the exchange - if it was connected or disconnected, what type of dial tone was required, was the phone line allowed to make local calls and long distance calls, and so on. A very basic terminal (keyboard and screen) was connected to the Operations and Maintenance Processor (OMP) which is where we would type in commands to connect, disconnect or change the phone line characteristics - this was called the telephone numbers category. The command to display the subscribers category was DISC: 372 4586; and the result would be something like C5 40 C3 - a set of hexadecimal codes which meant the phone line was disconnected and could not be used for outgoing phone calls or receive incoming phone calls. To change the subscribers category the command was CHSC: 372 4586 C6 40 A5; - with that hexadecimal code meaning the phone line could make outgoing calls and receive incoming calls. Hexadecimal was to become a second language for me..!! The last part of the phone line connection process was to test the line, to make sure it had a dial tone, and that there were no faults in the cable heading out into the street. Staff from other sections dealt with the street cables and the actual phones in peoples houses and businesses - my work was strictly in the telephone exchange. So this was my first task for a while - connecting and disconnecting phone lines in the exchange, manually running the wires to connect the phone number to the cable pair on the MDF, writing out the record cards, reading the meter, and programming the category on the terminal connected to the ARE-11 exchange. The Senior Technical Officer at Inala was Jeff and the Technician was Merv - both very nice people to work with. With Andy and I both working at Inala we got through the work on connecting or disconnecting phone lines quite quickly, so it was not long before I was also taken to visit Wacol exchange where Jim was the Technician. It also became apparent that I was entitled to a driving allowance if I had to drive the company car during the day. It was not much in dollar terms but my day was soon arranged so that I had to drive to or from Inala, Wacol or Sherwood most days. The cars we had were Nissan Bluebird station wagons and there was a distant photo of one on the first blog page - Jobs I've Had - Telecom Australia (1). The big orange Telecom Australia stickers on the side of the car were quite obvious and the red letter Z number plates also quite distinctive. I don't know exactly when I started to learn more about the ARE-11 telephone exchanges but I suspect it was quite soon. There were special services in addition to the normal telephone lines at exchanges, and there were also rotary groups which was the term for a business which had one advertised phone number but several phone lines working directly off it. I was soon taught by the Technicians how to connect the rotary groups which entailed special wiring in the equipment room, and also how to connect special services for bank data lines or fire alarms. Special services often needed additional wiring either on the MDF or in the equipment room to connect amplifiers or splitter/combiners into the circuit.
After my six months of field experience had finished the next main phase of my apprenticeship was back at Chermside but there was also a trip to Sydney. To be continued..... Continued from: Jobs I've Had - Telecom Australia (2) As mentioned on the previous post the task of physically connecting the pair of wires in the telephone exchange was only the first part of the job to connect a telephone service. Manual records were kept at the exchange and were either written by hand or typed on to small cards. As I said before, Inala had 7000 telephone lines so there were roughly 7000 small cards each with the subscribers name, address, phone number and cable pair on it as well as space for other details if needed. The cards were kept in drawers in numerical order for later reference, other similar but larger cards existed to record what was connected to each cable pair. So if you knew the phone number you could look at the small card to find out the cable pair it should be connected to, or, if you knew the cable pair you could look at the bigger card to see what phone number should be working on that cable pair. These local records were essential for fault finding when a telephone service stopped working, such as when a street cable was damaged. Another small part of the task was to read the subscribers meter for billing purposes. Unlike water or electricity meters which are in or outside peoples homes, telephone billing meters were at this time at the exchange. A special room was sometimes dedicated for the racks of small meters for each and every phone number. Inala exchange had a meter room, which I must add was a nice quiet room if a nap at lunch time was needed..!! Below is part of a meter rack with each panel holding 100 meters, each vertical rack holding 10 panels or 1000 meters. Inala exchange had seven of these racks to accommodate the 7000 phone numbers that could be connected there. If you were connecting a phone service for 372 4586 you would go to rack 4 (four thousand), panel 5 (five hundred) and write down the number on meter 86. This meter reading was recorded on the small subscriber record card and also sent to a central office for billing purposes. Each time a person made a local phone call the little meter would tick over and advance one number. For a long distance call the meter would tick over periodically based on the distance of the call and the time of day. When the monthly phone bill was due a person from the billing area visited the exchange and took a photo of each panel of 100 meters. The photos were developed and somebody in the billing area had to enter each and every number into the billing system. The billing system would subtract the previous meter reading from the current meter reading to determine the total number of calls made that month. Sometimes the little meters would jam meaning a subscriber would not get metered correctly and would get some free calls. If this was detected in the billing process the technician at the exchange would get asked to open the panel of 100 meters and replace the defective meter with a brand new spare part. There were also occasions when the billing area suspected the meter was working but not counting reliably, again giving the subscriber free or discounted phone calls. In this case the technician would make five test calls from the subscribers phone line and make sure five meter registrations were recorded. A little form filled in and sent to the billing area accounted for the test calls made by the technician so the subscriber was not charged for them. To complete the connection process for a telephone line there were a couple more things to do. A little bit of data needed to be entered via a terminal and a test made to make sure that the subscriber now had dial tone. I'll explain that further next time as it involves talking about the type of telephone exchange. The equipment was all Swedish and manufactured by L. M. Ericsson. The type of exchange switching equipment was called crossbar but it had been very recently upgraded to processor control - the system was known as ARE 11 - and I loved working on it..!! To be continued.....
Continued from: Jobs I've Had - Telecom Australia (1) As I mentioned previously, after completing one month of general training at the Chermside Training Centre I was temporarily allocated to Sherwood Exchange Maintenance Group - EMG for short. Sherwood EMG consisted of about 15 to 20 staff who undertook operations and maintenance work at Sherwood, Jamboree Heights, Darra, Wacol and Inala telephone exchanges. Staff members were generally allocated to one of those places but a few people were mobile and had use of company cars to get from place to place. We only had 3 or 4 cars for the entire staff to share as most people went to and from work in their private cars. On my first day here I was taken to Inala Exchange and met the technician and assistant technician who spent most days there. The assistant technician was Andy who, as it turned out, was the father of a girl I was at high school with - maybe it is a small world. Andy was my mentor for this period and he showed me how to connect and disconnect ordinary telephone services, or make changes such as somebody moving house within the same area, or requesting a change of phone number. Inala exchange had 7000 telephone lines with each and every one appearing as a pair of copper wires of a large Main Distribution Frame (MDF). The MDF was where the phone line was connected to copper cables which ran underground to each and every house and business in the surrounding suburbs. Copper cables as big as 2400 pairs of wires appeared on the MDF to allow connection and testing of phone services. To connect a telephone service the first step was to connect the cable pair allocated that ran to the address where the phone was being connected, to the telephone number which had been allocated, This information, along with the persons name, address and other information was originally sent by Telex from the Sales area. Red and white jumper wire was for an ordinary telephone service while green and white was for a special service like a pay phone or a data line to a bank. The photo below shows one style of MDF block with 50 pairs on it, and the jumper wires added to connect the cable pair to the phone number. On the internal or telephone number side of the MDF the jumper wires were run vertically, while on the external or cable side the jumper wires were run horizontally. The long and tall MDF had travelling ladders on both sides to make the task easier. Sometimes only a short piece of jumper wire was needed to cross from one side to the other, other times you had to run the wires from one end to the other using one or two of the travelling ladders. The bigger the exchange the bigger the MDF that was needed for the thousands upon thousands of connections. The vast majority of these jumper wire connections were soldered and several 50 volt soldering irons were placed on the MDF for this purpose. At the beginning of the day you would turn them on, and before going home you had to remember to turn them off. There was also a pair of small metal links on each cable pair and phone number which had to be inserted to make a connection - these were normally left in, but could be removed for testing purposes. Running the jumper wires to connect the phone number to the cable pair was only the first task, there were records to be written out, a meter which had to be read to record the number of phone calls made, and some data which needed to be programmed. To be continued.....
My first job when I left school was with Telecom Australia where I was employed as an Apprentice Technician (Telecommunications). I had an interest in electronics and a basic knowledge of electricity so I didn't think it would be hard - it wasn't. My first day on the job was Monday the 21st of January 1985. The Telecom Australia Training Centre (for Brisbane/Queensland) was located in Banfield Street at Chermside which is very close to Chermside shopping centre. At this time I had no car so the process was to walk to Bundamba station, catch a train to Brunswick Street, walk to the bus stop, catch a bus to Chermside shopping centre, then walk over to the training school. At the end of the day the process was reversed to get home again. It must have taken about 90 minutes at least each way, and would take even longer if you just missed a bus or train at Brunswick Street. The training complex had a mixture of brick and timber buildings - the brick buildings were for classroom/theory lessons, while the wooden buildings were for practical work like wiring up pieces of telephony equipment and fault finding. The brick buildings also housed the administration staff and a canteen. Also on the grounds there was a large radio tower which was progressively assembled then dissembled each year by a small group who needed that skill. I think we initially spent only one month here for basic training before we were allocated to a field location for six months practical experience. The reason was to ease congestion in the training school as there were 144 new apprentices each year, the full apprenticeship lasting three years.
We had no say in where we were sent, and I don't know how they decided, but after the first month at Chermside I was sent to Sherwood Exchange Maintenance Group, EMG for short. It was actually the perfect location as it was much closer to home, and immediately opposite Sherwood railway station. To be continued.... |
AuthorI love to understand things, how they work, why they happen - I'm always learning and keen to investigate... Archives
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