atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Does anyone have an ITT 601A KSU in use?

I see what you are saying, but this KSU has no B battery - Just AB and AG; which the manual says can be used for voice. But you answered my question - the intercom card does the filtering.

Thanks!
Matt

The funny part is that you don't hear any hum on talk battery suppiles unless it goes past 10000 ft.

Simple point. I will connect a ring down crkt with two car batteries.

The KSU has B Batt. Take your but sett and listen for it.

If this is a KSU 551 or greater they all have B battery.

This is how we wire the buzzers. 18-24 b batt.

DC does not run buzzers or bells.

You can create noise an a DC output. This should be a wakeup call on bad crkts within the network.

These older power supplies are unique.

Take your but set and connect one side to ground.

Then go across the power supply terminals to listen for the ac.

Now you have found the your ac crkt.

Sorry this is a lost art.

Hmmm

If it has a B battery, then all the documentation I have is wrong. The power supply schematic shows one 24 vdc output, one 18 vac output, and one 10 vac output. The 24 volt output runs directly to the AB terminal. Also, nowhere in any of the 50 pages or so of documentation is a B battery ever mentioned. Buzzers are fed from the 10 or 18 vac outputs, the lamps are fed from the 10v output.

My VOM can distinguish AC from DC; plus I have the schematic... no need to go searching.

Everything is as the documentation says it should be, with the exception that it says you can use AB for talk, and I get hum on it. The intercom card filters it out though, so the issue is resolved.

Thanks -
Matt

Matt said, He has a volt meter and never told us about how many 1a2 key systems that he has worked on.

Hey, Matt. The next time I need a volt ohm meter to work on 1a2 I will call you to waste my time.

A but set is a meter without a digital or analog meter such as a simpson meter.

If you spent years listening to electricity/capacity you don't need a meter.

It's kind of looking at it with a scope. The only difference is that your ears become your eye's.

SS, you missed it. He's using an ITT601 KSU and it has NO BB/BG. Doesn't need it, was a limited capability 1A2 KSU. Strictly CO lines and 10 Station IC. WE551's had more P/S and more flexibility, no question about it. Note that there were DC buzzers and bells used in the telco industry, early on. They became obsolete pretty quick, granted. Adjusting the contacts that made them work was probably the main reason, ya think! All that said, we are all having 1 h-ll of a good time watching Matt grow into the latest and greatest (And possibly the only)1A2 tech in the greater KC area. (Ahhh, the memories) John C. (Not Garand)