atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 1A2 key system A-Lead issue.

I’ve had an old 551 style 1A2 key system in my home for some time but it started acting up and I tracked the issue to the female amphenol connector on the 25-pair cable coming from the KSU itself (that connects to the male amphenol terminated 25 pair cable that came from the BIX).

The BIX was initially wired in parallel from the single cable and I’m rewiring the BIX block using the 7A multipliers that were supplied with the system (but never used when it was installed) with fresh wires from the KSU’s 66-block and from the 7A’s to the 1A’s the lines from the phones are terminated on.

The issue I’m facing is that the line 2 key on the 564 or 2564 telephone sets is triggering the a-lead on the line one key (causing the line one key to light up when its line two that pressed.) The hold key is also not working on this line key.

I have some 20 button ITT call directors what when I plug in and press like 2 - both line one and two light up but the actual telephone lines don’t come through - and I have one 564 set that the keys for both lines 1 and 2 are triggering both lines to light.

Any ideas where this issue is arising from in the system? The BIX is wired as it should be so I don’t get what is causing the issue as it all worked fine before.

Not sure what a 7a multiplier is, but if you're using a CPC connector, one feed to two phones seems like you had to isolate the v/br and v/sl pairs. It's been a long time but I remember these pairs had something to do with a speaker phone. Anyway, if it worked prior to your rewire, just backtrack to see where the issue started. Once you start throwing 10 and 20 button sets into the mix it's a whole new ball game.