1A2 10A2 KSU - Ringing slow to disconnect

[RMXRider]

We are fortunate to have the chance to support old ITT 1A2/10A2 KSU based phone systems.

Wanted to know how to make the line disconnect faster after CO trunks stop sending ringing voltage to the KTU cards.

Had a problem where the line would ring for 10 times after CO trunk stopped sending ringing tone, was able to replace card and get the rining down to 2 rings but no less.

Want it to stop ringing right away, anyone help here?

|Michael Berg|Communications Electrician|City of Los Angeles - Information Technology Services|555 Ramirez|Los Angeles, CA 90012|

http://ita.lacity.org

 

[TouchToneTommy]

Won't happen - the incoming ring triggers the ringing generator and interrupter to make the common audible ringers start ringing. If the call is abandoned by the caller, it is going to take some seconds of the abscence of incoming ring to cause the line card to stop the ringing, and then the interrupter still needs to complete its cycle.

When a call is answered, it's the A-leads that tell the line card that the call is connected, and stops the ringing even though the interrputer is still cycling.

 

[SYQUEST]

Tell me what type and version of line cards you are using and I will provide that info for the line card KTUs I have info on... I have modified the RING UP time out feature many times over the years for several types of 1A2 & 10A2 line cards.

1A2 & 10A2 are identical except that Automatic Electric called their 1A2, 10A2, because 1A2 was the Bell System.

....JIM....

 

[RMXRider]

for this problem, I was using Cortelco 183499-148 K400E's 9-94.

Does that help?

Thanks

|Michael Berg|Communications Electrician|City of Los Angeles - Information Technology Services|555 Ramirez|Los Angeles, CA 90012|

http://ita.lacity.org

 

[SYQUEST]

RMXRider,

For the K400E KTU to shorten the 10 second time-out cycle, remove the Z option strap between terminals 1 and 2, and replace the Z option strap with a 2.4 megohm 1/2 watt 5% carbon film resistor. Use one resistor lead as a strap between terminals 1 and 2 and connect the other end to terminal 3. This value will provide about a 5 to 6 second time-out cycle after the last application of ringing current to phone line.

You will need to form the leads of the resistor to fit the limited space on the option block of the handle. Small needle-nose pliers will work the best for forming and seating the leads. Be careful not to short terminals 3 and 4.

Let me know if this satisfies your requirements.

....JIM....

 

[1a22ip]

Boy does this bring back memories

ED

1a2 to ip I seen it all

 

[RMXRider]

Here is what I found out.

Did the 2.5 MOhm resistor, it shortened the disconnect to two almost three rings, a lot better than the 4 to 5 rings from an unmodified card.

Went to a 1.6 MOhm resistor, and it tightened up to 1 to 1.5 rings.

Unless anyone wants to warn me away from the 1.6 resistor, that is what I'm going to use.

Any un-intended consequences for going this route?

Thanks

Michael

|Michael Berg|Communications Electrician|City of Los Angeles - Information Technology Services|555 Ramirez|Los Angeles, CA 90012|

http://ita.lacity.org

 

[SYQUEST]

RMXRider,

No, there are no ill effects of going to 1.6 megohm, you just get a super short timeout period that's all. If that works for your situation, all should be fine. When I was modifying line cards in the past I had to do a lot of experimenting to get the ideal values for WECO, SAN/BAR, ITT/CORTELCO, and Automatic Electric. I never liked any of the Stromberg-Carlson 400 KTUs.

What that resistor does is control how fast a capacitor discharges to cause the timeout for the line card to go idle after the last application of ringing current.

....JIM....