sundance-communications.com/forum Forums TDM Business Telephone Systems Panasonic Telephones & Systems KX-T61610-3 No dial tone on handset p/u

Extension 11 does not give dial tone when handset is picked up. The line is "open", but no dial tone. The phone is programmed for "auto CO hunt". Speakerphone pick up activates CO1 and dial tone is heard (as programmed). I can switch to handset (by depressing sp-phone key)and successful transfer is made to handset. All other extensions work properly on handset AND speaker phone pick up. That is, they immediately go to CO1 and get dial tone. I have substituted other phones on Ext 11, and they have the same problem. The problem also shows up when the phone is plugged directly into the jack for Ext 11 at the KSU. What might be preventing extension 11 from getting a dial tone on handset pick up?

do a do a intercom 790#

I did an intercom 79#, and got data clear. System would not accept 790#. Still have problem.

Make sure CO1 button is actually CO1. On a display phone put phone in program mode, push CO1 button it should say CO1.

Confirmed that CO1 button is actually CO1 line.

Confirmed that CO1 button is actually CO1 line.

So It's ext 11 in the KSU that has the issue. It sounds like a defective component. I would bet on a bad photo-coupler or switching transistor associated with ext 11. I don't think that it is a programming issue. Time to swap extensions. If you plug in a single line phone and go off hook do you get intercom tone? Dial 81 to connect directly to CO1. Does it connect??

If I substitute a single line phone for the Proprietary Phone used on Ext 11 and go off-hook ----- I DO NOT get intercom tone. Obviously, I can't dial 81. The unusual thing is that if I go off-hook with the speaker phone button, everything works as designed. Thanks, Mark

That is odd. I am sticking by component failure. The speakerphone off-hook impedance is different than handset off-hook impedance. Photo-couplers sense the off-hook voltages and respond accordingly. If I had my schematic of your KSU, I could tell you what component was bad. I repaired hundreds of these KSU's in the 90's.

Alvaphonepro, Here is link to schematic for -1 unit (not -3). Possibly the part you are referencing is the same in both units:
https://www.ddrservice.net/files/Telephone/panasonic/kx-t61610-1.pdf