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WE Line Status Indicator

Started by JB-Alert, January 10, 2024, 06:38:03 PM

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JB-Alert

I'm in the process of connecting a 24A16 LSI to my home system.  When I connect a T&R from the LSI to a T&R extension from my Merlin Legend system, it works as normal (LED lights when off hook, LED flutters on ringing).  When I connect my Landline to the LSI, it doesn't respond. 

The BSP's description (463-210-101) says "The 24A is primarily intended for use with the No.1 Electronic Switching System (ESS) and the DIMENSION@PBX (CSS 201). It can be used with features such as call pickup, call transfer, and call forwarding to provide an alternative to key equipment." 

I was thinking since my landline comes from a #5ESS was the reason it doesn't work.  I double checked the polarity, grounds, etc and all are OK.

Any thoughts?

5415551212

Quote from: JB-Alert on January 10, 2024, 06:38:03 PMI'm in the process of connecting a 24A16 LSI to my home system.  When I connect a T&R from the LSI to a T&R extension from my Merlin Legend system, it works as normal (LED lights when off hook, LED flutters on ringing).  When I connect my Landline to the LSI, it doesn't respond. 

The BSP's description (463-210-101) says "The 24A is primarily intended for use with the No.1 Electronic Switching System (ESS) and the DIMENSION@PBX (CSS 201). It can be used with features such as call pickup, call transfer, and call forwarding to provide an alternative to key equipment." 

Thats interesting I had never herd of a 24A till now. Can you find the specs / schematic or BSP for it that show the input tolerance for ringing the off hook?

I thought Merlin was a digital system ? I suppose it must have an analog card / port for a regular phone and you connected to that ?

'Off hook' on a pots line usually is detected by measuring miliamps or voltage drop.
'Ringing' would be 90-105V @20HZ 
So if you have access to a multimeter or another way to test that on your posts line thats where I would start.

Quote from: JB-Alert on January 10, 2024, 06:38:03 PMI was thinking since my landline comes from a #5ESS was the reason it doesn't work.

Could be an issue with the actual line or your not served loop current anymore rather a 'VOIP' 'last mile' type system on your block. Either way getting some measurements will help. I doubt it is an ESS issue for those two features.

G-Man

#2
"The LED is used to provide the indicating light for each line. The LED chosen by Associated Instrument Mfg. Corp. for use in the Line Status Indicator is red and has a typical forward voltage drop of 1.8 volts D.C. at 25 mA thus providing an average power dissipation of .045 watt."
Quote from: 5415551212 on January 12, 2024, 11:38:59 AMCan you find the specs / schematic or BSP for it that show the input tolerance for ringing the off hook?
"The optoelectronic photocoupler is the main component in the ring detector portion of each circuit.
It consists of a neon lamp coupled to a photoconductor. The neon lamp is connected across the tip and ring sides of the line.
The talk signal, being either twenty-four or forty-eight volts, has no effect at all on the neon lamp.
However, when the ringing signal is applied, the neon ionizes and light shines on the photoconductor changing the resistance from approximately two megaohms to approximately two thousand ohms."
 
JB-Alert-
  • Is the unit labeled 24A or are you assuming it is this particular model?
  • What is the line current?

 

SUnset2

If it uses LEDs, it is probably polarity sensitive.  Did you try reversing polarity?

JB-Alert

Thanks for the suggestions, here are some answers:

The polarity is correct; the attached picture shows two lines.  The first red LED is slightly different in appearance because that line is ringing.  The next LED, brighter, is showing a line in use.  These are connected to two T&T lines from the Legend.

The Legend has T&R boards installed, and these 3 digit extension numbers are wired to the LSI.

The buried landlines coming in to my house are about 15 years old, and are not VOIP.  When I tried to get an additional landline line last year, the foreman told me no new installations until my neighborhood converted to fiber.  Not going to happen since the HOA provides high speed internet and phone via Spectrum to every member, and they own the cables.

AT&T told me my neighborhood is served by SLC-96 carrier loop system.

My next test this weekend is to remove the 400D KTUs that connect to the landlines to see if that makes a difference.  When I connected before, I wired the LSI ahead of the KTU, but the KTU was still connected.

Lastly, here is the only description I could find on the LSI's operation:

"The 24A indicator bridges across the T and R leads of lines to be monitored and indicates the status of these lines. There is an LED (light emitting diode) associated with each of the monitored lines. This LED is off when the line is idle, on when the line is off-hook, and flutters at a 20-Hz rate when the line is ringing. In addition, a tone ringer is sounded when any line being monitored is ringing. The 20-Hz lamp rate and audible signal are activated only when ringing voltage is actually being applied; they are not activated during the
silent intervals. Therefore, the 24A will provide the same distinctive ringing patterns provided to
stations in the DIMENSION PBX (CSS 201)."

Thanks for everyone's help!


5415551212

That is a neat unit.
Check your POTS line ringing voltage with both the KSU connected and disconnected.

JB-Alert

Hi,

I tested again by pulling out the KTU that was attached to the POTS line (instead of connecting the line ahead of the KTU). It worked!  I don't know what the 400D does to the line, however the LSIs were designed to work off of non-KSU lines.  When I have more time, I'll try another experiment to see if any of the later KTU series makes a difference.

The LSIs are nice little devices, in 8, 16 and 32 line configurations.  The ringing tone signal they give is very nice compared to some other electronic ringing tones.

Thanks everyone for your suggestions.

Regards