atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 1A2 and some old WECO stuff

Update on the project:

551C KSU has been mounted to the wall next to my Ascom 2030 ISDN PBX (4 analogue lines run from this PBX to the KSU), connected to common ground and commissioned to regular service.

Control board for PowerDsine ringing generator has been made - I simplified it versus originally planned design. It actually takes only rectifying bridge, one filter capacitor and a protective 300 Ohm 3W resistor for the output 70Vrms circuit. As planned I've added a miniature lamp to indicate active state of ring generator - it flashes whenever ringing signal is sent to the common audible pair. Right side of the board is not needed actually, but I've decided not to cut it for the time being as I may need to place an additional relay on it in the future.



All mounted on the metal bracket from the construction supermarket. Back side of wiring board is potted into hotmelt glue to protect from short circuits. Only 2 pairs coming out: 10VAC in from interrupted common audible (white-red) and 70VAC output (white-yellow) for ringing signal to the system common ringer pair. They are terminated to 551C KSU's 66 block.



Bracket is mounted using one of the original holes for ringing generator mounting bracket (the unobtainable one). It covers part of the 66 block, however if needed it can be turned up or down from this position to open access to corresponding terminals of 66 block. I could turn it around to position it above the interruptor, but I don't want to occupy space for 5th line card in the 551C KSU, since it will be added later.



Miniature 12V lamp is connected in parrallel with ringing generator to the output of integrated rectifying diode bridge. So it lights up following the cadence of ringing signal.



With full uncut board KSU cover still perfectly fits - so everything is left as it is now. Probably I will make one day an Issue 2 control board with improved appearance and functionality. For now this works perfectly.



I have finally opted for using existing switching relay in Ascom 2030 PBX instead of installing additional one into the KSU. This relay has one set of contacts (normally closed and normally opened), which is activated by a button on the system set or via phone code. I wired this relay to switch common audibles from ringers (via control board and PowerDsine ringing generator) to buzzers (10VAC) and back. So now I can instantly switch between these two modes by dialing special code 12-75 on any of 1A2 sets connected. Very handy function for keeping the system flexible.

Software

Now when the stage one hardware works have been completed on my 1A2 system, I've spent some time programming the Ascom 2030 PBX to deal properly with 4-lines wired into KSU:

Hunting group has been created to cycle the extension numbers in the KSU. PBX provides extension 40 (Line 1), 41 (Line 2), 42 (Line 3) and 43 (Line 4). Now if any of called extensions is busy, the next line button will ring. Group is circular, so if Line 4 (extension 43) is busy, system will come back to Line 1 or any free line button available.

With incoming external calls it looks cool: first incoming call on my external number appears on Line 1 button. If I occupy this button and somebody calls my number at the same time, this call will appear on Line 2 button. If both are busy, then it will hunt further and indicate call on Line 3 button. Finally if I have 3 lines in use (on hold or in conversation), next incoming call will appear on Line 4 button. This is how business telephone system should work in my view: incoming line should never be busy (unless I occupy all 4 lines).

I could extend it to Line 5 button, however it is reserved for mobile phone integration via Bluetooth gate in the next release.

2872A2M Touch-A-Matic update:

Battery repair. Each 2872A2M Touch-A-Matic set is equipped with 1200 mAh 5V Ni-Cd battery. Nominal life cycle of this battery is 4 years according to BSP. My set has battery dated 1980, so no chance to hope old cells can give anythings after 37 years. Actually this battery already started to leak, creating some damage to the connectors and metal base around the battery. See picture of RJ11 connector on the battery.

Battery housing is sealed, so I have to saw it around the seam to get access to accumulator cells.



Inside the black box I have found four 1.5V cells mounted on hotmelt glue, all in salt and electrolyte. Quick search on eBay revealed exact size battery pack used for AEG portable vacuum cleaner. Difference is that it is Ni-MH and hence has slightly higher capacity of 1600 mAh. So Touch-A-Matic can withstand longer power outrage than with the original battery.



My guess was correct and ordered batteries fit perfectly into the original box.



First step of repair - RJ11 connector has been changed to a new one. No cleaning would have helped with the damage from leaking battery.



Wires have been soldered to the new battery terminal and it has been assembled back with sealing the perimeter with hotmelt glue. 2872A2M has a lockout to prevent using the autodial function without battery connected. In reality this lockout is only 2 black wires bridged together and connected to the negative terminal of the battery pack.



That's it - battery is installed back to Touch-A-Matic set and tested for memory retention without the AC power. I don't know how energy efficient memory circuits are in this 1980 telephone set, but this accu pack can power a vacuum cleaner for couple of hours I believe. So I can only imagine how long memory chips would eat all this 1.6 Ampere-hours to run it to zero.

Still looking for somebody in the possession of Touch-A-Matic set with speakerphone function. I would appreciate just some pictures of this option board to be able to produce it on my own.