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

Speaking of the 4A speakerphones.... In AT&T's headquarters we had mostly 4As in small conference rooms. But the problem was "mute" would only mute as long as you held the button down. The ingenious solution was while holding the button down, slide a penny between the button and outer shell. Perfect thickness to keep the button down! Of course, before the first year of Divestiture was even over, the New Jersey Bell Centrex was removed, and replaced by a System 85 (1A2 equipment & phones were hauled out by the dumpster). The mute on the new voice terminals was toggled on and off, saving meeting participants money!

I know this story! This is why instead of a penny I use a PVC covered paper clip. Sorry to say, but none of post divestiture speakerphones provide a comparable quality of sound in comparison to 4A. When you save metal, you save metal and loose the sound. I say as an expert in acoustics.

I never can stop, when I should. My wife and Arthur know that.

Now extended to Revox B790 vinyl player.



Home studio is growing:

A way for old employees to make money in the 1970's:

Tell the new employees to place a quarter ($0.25 coin) in the "Make Busy" contacts of 197-type step-by-step switches, if they found a switch that was defective. The older employees would come around later that day and replace the quarter with a penny. Then the next day they would repair and/or adjust the switch, and leave the penny on the switch shelf for the new guy to retrieve. Profit per switch: $0.24.

Tube amplifiers are cool and fancy. What about tube power supply?

Well... here you are:



I bought a used mixing console with no power supply. Before I find one factory made, I made this temporary setup. Console requires 2 coils of 19VAC. This is exactly what I have from my 1A2 transformer (2 by 18VAC each). But this guy is dangerous: it’s a big transformer and rush-in/rush-out energy is huge. When you unplug it from current on primary side a higher voltage is induced in the low side. This killed an integrated rectifier (bridge) in my very first 4A Speakerphone, which I powered from this transformer. After several on/off cycles it died till I found the faulty bridge, resoldered it to just a jumper and since that time have to power from filtered 24VDC with taking care of polarity.

Since that time every transformer I work with gets a dedicated varistor from Siemens&Halske with rated voltage. However, quick checks this time showed that it doesn’t help with this transformer. Powering off induces ~100V peak on the 18VAC coil at power off. Looks varistors are slow triggered devices which can help in case of constant overvoltage.

Didn’t have time yesterday to bother with Zenner diodes, so just plugged in a 220V light bulb across both coils (36VAC nominal). It lights a bit during the operation in normal. Mode, but is supposed to absorb any of peak voltages at transition states. Similar to bulb protectors/fuses in some of old switches.

Simple things sometimes work so good in this world!!

Update: (after a while)

Finally my beige 2872A2M Touch-A-Matic works with matching color PC 4A Speakerphone. Rare kit of parts required for converting 2872 to speakerphone service is extracted from black TAM I’ve just received. That one will require some good repair: part of power supply board is burned out. But for now Speakerphone board is enough.
Thanks to Arthur for relaying this TAM to me.
Appreciate if anyone can share the SD of TAM set (2872A2M) or just PSB (power supply board). Will need it for repair.

It's little...It's lovely...It lights





It’s energy efficient: with 2 LEDs instead of incandescence bulb lamp. It’ll soon be part of 1A2 with Western Electric 6050 key strip.

I may have good news...

A friend reports that he has located both circuit boards required to do the "one touch dialing w/ speakerphone" option on a TAM 32.

Stand by for updates!!!

That is very good - I’ve a couple of spare TAM 32’s waiting for speakerphone option. TAM 32 with speakerphone is way different level of service vs. plain TAM 32. I wonder why they haven’t included this option by default and just charged higher lease in the first place.

Just a curiosity question. Did anyone ever involved into the old Bell System service organization know, why TouchTone dials specifically used for Princess phones were less reliable then regular TT pads?

I have plenty of WE old TT pads in my various 1A2 telephones - none of those ever required any repair or adjustment, except taking care of proper polarity.

However, having now 2 princess phones and having done a market research on those on eBay, I see that many of Princess do not dial out.

The first one that already arrived I have repaired by re-tuning the high and low frequency coils with a frequency meter, so now it dials out perfectly. However, I have never came across the lost tuning on other WE TT dials and never touched those factory adjusted coils.

In my view difference of Princess dial was only in transparent buttons, but not in frequency generator electronics. And the coils used are the same. Could it be that for some reason coils in Princess phones were not fixed with paint/glue after factory adjustment and so after years of vibration they may turn a bit causing the frequencies to creep.

Have no idea but very curious about this.