POSSESSED 8X24/DR5.1

[leardini]

I’m the 3rd vendor hired by a Doctors Office to solve this problem. It’s been now 8 months since I’ve started working on this and I’m about ready to give up. They have a Meridian 8x24 KSU with DR5.1 Software, 16 x M7324 Sets and a PC based Voice Mail, which I don’t know much about (I’m only working on Norstar line of Voice Mails). The system drops calls like crazy. It usually happens in early morning hours (when they have a lot of incoming traffic). A few times I called from an outside location and I hear a half a ring and get disconnected. Now before someone HOPEFULLY instructs me where I should locate this problem let me start by telling you what I’ve done so far.

1.Replaced the KSU/Software/2P Exp Cartridge/Trunk Module/DS card.

2.Sold the KSU pulled out of this office to another client and it works fine.

3.Pulled new cables from Floor Closet to Doctors Office Closet for the 9 telco lines going into the system.

4.Toned station cables & replaced all jacks going to extensions on the system.

5.Installed a brand new Smart UPS APC-1400 for the system.

6.Completely disconnected (for 1 week) the PC based Voice Mail from the system but it was still dropping calls.

7.Had Telco (SBC) move all the lines to new binding posts coming from the street to the tower.

8.Moved lines to new cable pairs in the house cable running from building basement to 11th floor (Floor Closet).

9.Had Telco run all kind of tests – they blame it on my equipment.

10.Installed a SL phone before the KSU on a particular line – NEVER DROPPED ONE CALL ON THIS Single Line set.
Am I crazy? Am I missing something? At this point I’ll try anything. Pls HEEEEELP!
Thank you!

 

[westcoaster]

do all lines drop at the same time? example: calls on lines 1, 3, 5, 7. Do all four lines drop at the same time? or only the call on line (?) while the other three carry on their conversations.
Removing disconnect supervision would be good at this point...
My ops manager worked in a hotel once (California) that had a t1 that went funny every day at a certain time. Turned out, as the sun would rise in the morning it would shine on the wirewrap cross connect. the wirewrap was done just loose enough the heat would expand the wire and break the connection momentarly. he had been chasing that one for months...

 

[Arr]

Westcoaster,
Had a similar in a hotel where for a short time in August several rooms would lose their service. Happened every year. Usually corrected by evening to recurr the next day. Turned out that there was a bad cut on the tail of the rooms pair on the 66 punch down block. As the temp rose and the air ccnditioner in the PBX room struggled these little tails would expand into the next terminal ans short out the pair. This all in a scroggy PBX room in a 100 year old scroggy hotel with 100 year old telephone wiring still in use etc. They thought it was just the ghost.

Cheers
PhM

 

[phonesrus]

This sounds like a problem that I had with an Iwatsu ZTD about 10 years ago. Same symptoms, drove me nuts for about 8 months! Started after a remodel of the office. The problem was static electricity. Synthetic fabrics/materials are bad about developing static charges, carpet, chair coverings, floor mats, clothing; add them all together, bang! We did about everything that you have done, and more. I found the answer by accident, I was sitting at one of the user desks, slid across the floor, and picked up the phone to make a call. The phone went nuts, all the lamps flashed and the phone went dead, no dialtone. We sprayed all the carpet and chairs/floormats with anti-static solution, even drilled a hole in each floormat and installed a drain wire to electrical ground, we even had to ground two wall phones in the halls to the red-iron. Turned out that the building also had a large dehumidifier in the air handler system which probably contributed to the problem, dry air!

 

[jerryreeve]

Can you put an SMDR on it and get a coordinated look at lines that calls are dropping on or if multiple lines are dropping? JerryReeve
Communications Systems Int'l
com-sys.com

 

[leardini]

Well here are the findings:
No ALARMS and no EVENTS in the log. The Voltage on the lines looks OK but I can't say the same about the loop current:
L01 50.2V 35.2mA
L02 50.2V 35.3mA
L03 50.2V 31.3mA
L04 42.7V 39.9mA
L05 50.3V 33.9mA
L06 50.1V 33.9mA
L07 49.9V 34.1mA
L08 50.4V 34.4mA
L09 50.4V 33.7mA

Line 4 is a Centrex line and comes off the Hospital's PBX. Each Doctor's office in the building has a line from the Hospital. Now, who should correct this "loop current" problem? Since I've had line 4 connected to an MICS and never dropped a call, do you guys think that the MICS tolerates this values of over 27mA better than the 8x24? Thank you all again!

ML

 

[Arr]

ML,
Loop ;current is a product of load and voltage. YOur loop current is unlikely to be an issue. If you put resisters on the line you will increase loop current and not solve your problem.
The less voltage you have with a given load the greater the current will be. The greater the voltage the less current ... but there has to be a balance of voltage and load for all to work well.
Lower the voltage by two volts and check the difference.

Cheers
PhM

 

[exsmogger]

You have it backwards. Ohm's law states that I = V/R (I = current, V = voltage, R = resistance or load. By adding resistance current will be decreased. An increase in voltage will result in an increase in current. Brian Cox
J & J Communications

http://www.jandjcommunications.com

brian@jandjcommunications.com

 

[jerryreeve]

Loop current causes some really phreaky problems for phone systems. I have a link here for a tutorial about loop current. I have found this page to be interesting reading, and useful.

http://www.sandman.com/loopcur.html

the link also has some loop current attenuators. JerryReeve
Communications Systems Int'l
com-sys.com

 

[leardini]

OK...
Will telco correct this problem if made aware?

Does anyone know if MICS tolerates this currents (over 27mA)?

Should I just go ahead and order those Loop Current Attenuators?

After taking this measurements makes sense to me that this is the problem because if you look at Line 04 (this is the line with most problems) I measured 39.9mA.

jerryreeve
I was on that web site just last night and I think everebody should see it.
Thank you.

 

[samh30]

I think you should contact Teleco to try to fix that,or you can use attenuator to drop the loop current,But I think your reading is inaccurate maybe due to faulty meter or insensitive meter because they are very high,and even the Mics has some tolerance but with these values the circuit card for lines will be damaged by now ,its very unlikely that you have 39.5ma for an accurate measurements,but anyhow you have a high loop current and thats why maybe you have these weired problems.
You will need to do something about that quickely before you damage your MICS system. Good Luck!

http://www.samhassan.com

 

[leardini]

samh30
I'm sure my meter is good. I used the same meter (after getting back from the Doctor) to measure the loop current on my lines and it measures 25mA on all lines. The MICS is disconnected the line (4) is back on the 8x24. Got your point; SHOULDN'T PUT A LINE WITH SUCH HIGH LOOP CURRENT EVEN ON THE MICS. I'll call telco and if they can't fix it then I'll get the Loop Current Attenuators. If anybody is still interested I'll let you know how it turns out. It will take a while to get telco there. I wanna thank all of you for pointing me on the right track and let's hope this works.

 

[Arr]

exmogger,
If all we were dealing with was ohms law you would be correct. BUT where an electronic device needs a certain amount of energy to operate, it will take that energy in either voltage or current. There will be top and bottom ends of acceptable voltage and current where the device will operate to but then will cease to work.
In short if an electronic device needs 50vdc and gets 48vdc it will likely make up the differnce with extra amperage. Too high a voltage could be as much of a problem and too low a voltage.
Leardini could lower the loop voltage to -48vdc and get good results. This will not lower an electronic device's amp draw.

PhM

 

[Arr]

Leardini,
Did you check your grounds?

PhM

 

[leardini]

Arr
I didn't personally check the ground yesterday. 8 months ago when I first started troubleshooting this the doctor had an electrician check the electrical outlet and dedicate an outlet for the phone system. I mentioned to them yesterday to have SPAKY doublecheck the outlet and make sure it has a good ground. I'm still waiting on this.

 

[leardini]

Just spoke with the electrician. Ground is good.

 

[Arr]

Exmogger,
I apologise and stand corrected.


0------- 30ma -------- 25ma ----------
| |
1.5K Line card
@7.5vdc Ohms Load xx
off hook | |
voltage | |
0--------------------------------------
To divert 5ma and bring current down
per above:

1.5kohms = 7.5vdc/5ma

Leardini,
This should help. Any electronics store will have a 1.5kohm resistor in stock. They are cheap. You might also try to use a 5ohm resistor placed in series on the - leg to bring the voltage down a little. Look for reversals.
None of the above is guaranteed to fix your problem but.

Samh, Exmogger, and Westcoaster,
Rgds
PhM

 

[exsmogger]

No problem. We are all just trying to help. Brian Cox
J & J Communications

http://www.jandjcommunications.com

brian@jandjcommunications.com

 

[Arr]

Exmogger,
Yeah. I know. But..........

Rgds
PhM

 

[leardini]

Arr
Still wainting on PacBell but...if I understand correctly the 1.5K resistor should be placed between T & R of a line??

 

[Arr]

Leardini,
That is correct. It provides an alternate path for current to flow thereby reducing the current to the line card. Total current in circuit will still be the same, just the portion going to through the line card will be less. The figures I used are approximate. You should plug your own figures into the equation to get the most acurate results. If you place a resistor in line with tip you will lower the voltage which to get it down to -48vdc probably wouldn't hurt.

PhM