Mitel Sx 200 El/ml Technicians Handbook

							Troubleshooting and Repair
61
Troubleshooting
4. To return the circuits to service, select: 
DIAGNOSTICS
MORE_KEYS
RET-TO-SVC .
Replacing a Main Controller Card
When replacing a main controller card (MCC), you must ensure that the 
replacement MCC and the installed MCC match – both in card type 
and stratum clock type. This procedure applies to the MCC II,
MCC IIIEL, MCC Yields, MCC IIIML, and the MCC in the SX-200 
LIGHT/DIGITAL PBX.
1. Quit the customer data entry mode. 
2. If you do not have an up-to-date database backup, create one now. 
3. Power-down the Control cabinet.
4. Remove the old MCC. 
5. Remove the system ID module or decryption module from the old 
MCC and install it onto the new MCC.
6. Transfer any modules from the old MCC to the new MCC.
7. Install the new MCC.
8. Power-up the cabinet. 
9. Verify the system date and time. Correct as required.
10. Restore the database. 
Refer to Backing Up a Customer Database (page 27). 
Refer to Powering Down the Nodes (page 57).
CAUTION: Wear an anti-static wrist strap whenever you 
handle circuit cards.
Refer to Powering Up the Nodes (page 59).
Refer to Restoring the Database (page 55). 
						

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Correcting Ground Path Problems
Safety ground absorbs the dangerous voltages that come in contact 
with the PBX cabinet. The safety ground connects to the PBX through 
the ground termination of the system’s three-prong power cord.
System ground provides a stable ground reference for the voltages the 
the system uses. The system ground attaches to the PBX through a 
separate ground wire (6 AWG recommended) that connects directly to 
a system cabinet ground-stud. 
In most buildings, the metallic cold water system provides the ground 
source. It must provide a metallic connection all the way back to the 
building entry point (including a metallic strap that connects around the 
water meter).
Problems Caused by Incorrect PBX Grounding
If the CO and PBX have different ground reference voltages, each can 
fail to recognize the signals that the other sends. For example:

Ground start trunks may not seize when the PBX grounds the ring 
lead.

The CO may not release trunks when the PBX removes its 
termination.
Low-frequency AC ground differentials can disrupt the operation of PBX 
logic circuits and cause incorrect operation or system failures.
AC ground differentials at radio frequencies can cause audio 
interference and possibly disrupt PBX logic circuits. 
						

							Troubleshooting and Repair
63
Troubleshooting
Ground Path AC Voltage Test
This test measures the presence of AC voltage in the metallic loop.
1. With your meter connected in the same way as you did for the resis-
tance test, measure the AC voltage.
2. Start with your meter set for high AC voltages and adjust it down 
until you get a reading.
3. You should get a reading of 1 Vac or less.
If your reading is greater than 1 Vac, check to see if your electrical panel 
ground connects to the building ground. Depending on local utility 
regulations, the connection usually exists between the electrical panel 
ground and a cold water pipe entering the building. If this connection is 
present, try an alternate ground point(s) and measure the AC voltage 
again.
If the system ground and safety ground both connect to the building 
ground, your measurement is the metallic loop from the PBX chassis, 
to the electrical panel ground, to the cold water pipe, and back through 
the system ground wire.
If the safety ground and system ground do not connect at the electrical 
panel, your measurement indicates the AC voltage differential between 
protective earth and the building ground.
Ground Path Resistance Test
1. Turn off the main PBX system circuit breaker.
2. At the PBX system, connect the cabinet’s chassis ground to the 
electrical panel ground. The wire should be a minimum 10 AWG and 
not longer than 15 meters.
3. At the PBX system, disconnect the ground wire from the system’s 
ground-stud.
4. Set your meter to OHMS at the highest scale.
5. Measure the resistance between the PBX chassis safety ground 
and the ground wire that provides the system ground. Adjust your 
meter down until you get a reading. 
						

							Technician’s Handbook
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6. The resistance between the two grounds should be less than five 
OHMS. If not, try alternate ground point(s) and repeat the test.
Testing the CO and PBX Ground Differential
If a PBX experiences trunk lock-ups, or trunk seize failures, perform the 
CO/PBX Ground Differential Test.
This test determines whether the DC ground potential between the 
selected building ground point and the CO ground point is within 
acceptable limits by measuring the two currents: “Loop” current and 
“Ring” current. 
Divide the measured “Ring” current by the measured “Loop” current to 
determine the relation of the building ground potential to the CO ground 
potential. The result is 2.0 if the CO and PBX ground points are the 
same potential.
A result between 1.85 and 2.15 indicates an acceptable building 
ground. A result outside these limits means that you must locate an 
alternate building ground.
1. Disconnect the building ground wire from the PBX ground-stud.
2. Disconnect a loop-start or ground-start trunk from the PBX.
3. Measure the Loop current.

Set the meter to Milliamperes = DC and Range = 200 
Milliamperes.

Connect the meter between the Tip and Ring trunk leads.

For a ground-start trunk, apply the building ground momentarily 
to the ring side of the trunk. This application of ground will signal 
the CO to complete the loop and provide DC loop current.

Allow sufficient time for the current to stabilize and record the 
loop current.

DC Loop Current = _______________________ 
						

							Troubleshooting and Repair
65
Troubleshooting
4. Measure the Ring current:

Set the meter to Milliamperes = DC and Range = 200 
Milliamperes.

Connect the meter between the Ring trunk lead and the 
building’s open-ended ground wire. Be sure that you disconnect 
the building ground wire from the PBX ground-stud.
5. Allow sufficient time for the current to stabilize and record the Ring 
current.

DC Ring current = ________________________
6. Calculate the CO/PBX ground potential by dividing the Ring current 
value by the Loop current value.
Checking the Port Connections
to the PBX
Refer to information showing the pin numbers and signals for the T1 
and PRI Trunk Port, Table 41 on page 201, the SFT Port,Table 36 on 
page 199, the Copper Interface Ports,Table 38 on page 200, the 
Maintenance Terminal and Printer Ports,Table 39 on page 200, or the 
Maintenance Module Port Table 40 on page 201, in this handbook.
Checking the Receiver Allocation
Receivers allow devices which use DTMF signaling to communicate 
dialing information to the PBX.
DTMF Receivers (DTMF Module)
DTMF receiver modules may be installed on a Universal Card. Each 
Universal Card can contain up to four receiver modules; each receiver 
module contains four receivers, for a total of 16 receivers.  
						

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BCC III (DSP Module)
Sixteen DTMF receivers are provided by a DSP module on a BCC III.
DTMF Receivers (DSP on MCC IIIEL, MCC IIIELx, MCC IIIML, or 
MCC II)
Seven DTMF receivers are standard on each MCC
(CDE Form 04,Option 68).
CLASS / DTMF Receivers (SPINE Control Module II)
Seven DTMF receivers are standard on Control Module II. Receivers 
not assigned as CLASS receivers are available to the system as DTMF 
receivers. CLASS receivers are only available to the devices in the 
same bay.
SPINE Receiver provisioning for CLASS trunks (CDE Form 04, Options 
61-67) is provided in the following table.
Table 4:  SX-200 SPINE Maximum Receiver 
Combinations Available 
CLASS ReceiversDTMF Receivers
07
16
25
34
43
51 
						

							Troubleshooting and Repair
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Troubleshooting
Checking the FIM/CIM Carrier Cards
1. Verify that the cards with the interface module are installed in the 
correct card slot for the assigned bay.
2. Verify that the interface modules in the main control cabinet are 
correctly connected to its peripheral bays.The configuration 
positions are hard coded in the software.
3. Verify that the same distance variant of FIM is installed at each end 
of the link.
4. Verify that the dip switch on the Control Triple CIM card is set 
properly. Open switch 4 to set the card as a triple interface card and 
close switch 4 to set the card as a double interface card. Opening 
another switch substitutes a CIM circuit for the add on FIM II.
5. Verify that the PRI card in a peripheral cabinet has its own FIM II or 
CIM.
6. Verify the System Options 71 and 72 in CDE Form 04.
7. Verify that the configuration in a seven cabinet system meets your 
needs.

With an MCC IIIEL control card, the Control Triple FIM Carrier 
card and the Control Triple CIM card provide two links per 
peripheral bay. Blocking may occur if two T1 trunk cards are 
installed in a peripheral bay that connect to the Control Triple 
FIM Carrier or the Control Triple CIM card.

With an MCC IIIELx control card (installed in a SX-200 ELx 
cabinet PN 9109-600-002-NA) the Control Triple FIM Carrier 
card and the Control Triple CIM card provide three links per 
peripheral bay. The MCC IIIELx card supports a non-blocking 
seven cabinet system.Setting the Control Triple CIM card as a triple interface card 
without a MCC IIIELx provides a system for low traffic 
configurations such as hotel/motel. For heavy traffic 
conditions a MCC IIIELx should be used.
Place the first FIM carrier card or Control Triple CIM card in Slot 10; 
the second FIM Carrier card or Control Triple CIM card in slot 11.  
						

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Checking the T1 Card, T1/E1 Module, 
and the PRI Card

In the SX-200 EL system, LIGHTWARE 17 supports one digital bay 
with two T1 trunk cards and the other digital bays with one T1 trunk 
card to total a maximum of seven T1 trunk cards.
LIGHTWARE 18 and greater supports a maximum number of eight 
T1 links in the SX-200 EL system. These links can be from the T1 
cards and from the T1/E1 modules. Any bay can have a maximum 
of two T1 links to a total of eight T1 links in the SX-200 EL system. 

The system (with MOSS option, Number of Links 0-8) allows a 
maximum of eight T1 type links. Included in the count are T1 trunks 
from the T1/E1 module on the BCC III and the T1 ISDN links from 
the T1/E1 module on the PRI card.

The BCC III supports one T1/E1 module that provides one or two T1 
links. The SX-200 ML system supports a maximum of two T1/E1 
modules with a system maximum of four T1 links. The SX-200 EL 
system supports a maximum of seven T1/E1 modules with a system 
maximum of eight T1 links.

The T1/E1 module has two LT/NT connectors (jumpers), one for 
each T1/E1 link. These connectors must be set to the NT position 
(the default setting) for T1/D4 functionality.

If you install a T1 trunk card in slot 10 of a bay, you cannot install a 
peripheral interface card in slot 5; if you install a T1 trunk card in slot 
11, you cannot install a peripheral interface card in slot 6.

If you program the first T1 link from a T1/E1 module on the BCC III, 
you cannot install a peripheral interface card in slot 5; if you program 
the second T1 link from a T1/E1 module on the BCC III, you cannot 
install a peripheral interface card in slot 6.

If a PRI card is installed in slot 10, you can install a peripheral 
interface card in slot 5; if a PRI card is installed in slot 11, you can 
install a peripheral interface card in slot 6. Because you program the 
PRI card as its own bay, the PRI card does not occupy slots 5 or 6 
in the bay that the card sits in. The T1 links from the PRI card occupy 
the software slots 5 and 6 in its own bay.

The PRI card requires a SX-200 ELx cabinet and a Stratum 3 MCC. 
						

							Troubleshooting and Repair
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Troubleshooting
Checking the Number of T1 
Trunk Cards
With LIGHTWARE 18 Release 2.0 or greater software, any peripheral 
bay can have up to two T1 cards to a total maximum of eight T1 links 
(with T1 Cards and T1/E1 modules) in the system. 
Prior to LIGHTWARE 18 Release 2.0, the maximum number of T1 
cards was seven. The following table defines the maximum number 
(prior to LIGHTWARE 18) of T1 Trunk cards in peripheral bays that can 
connect to a Control Triple FIM Carrier or a Control Dual FIM Carrier in 
the Control cabinet (cabinet 1).
Table 5:  Maximum Number of T1 Trunk Cards
Prior to LIGHTWARE 18
Cab 
#0 CFCII 
or
0 CFCIII 1 CFCII
(ML)1 CFCII
(EL)2 CFCII
(EL)1 CFCIII
(EL)2 CFCIII
(EL)
1 CFCII 
(10)
1 
CFCIII 
(11) 
(EL)
12110100
2222222
311111
4111
5111
611
711
max.2345576 
						

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Trunk Signaling and Supervision
General Signaling & Supervision Concepts
All trunks share similar basic handshaking functions. The actual 
signaling mechanism will vary with the trunk type. 
Seize: (request to make a call) The calling party initiates the call by 
requesting service from the called party.
Seize Acknowledgment: (ready to receive) The called party indicates 
that the call can commence. 
This acknowledgment occurs when the calling party expects a 
response (Dial Tone) or when the called party needs time to establish 
appropriate resources (DTMF receivers).
Digits: (who to talk with) The calling party generates the rotary pulse or 
DTMF. 
Stop Dial: (slow down, can’t handle the pace) The called party 
generates a signal to indicate that digits are in risk of being lost.
Receipt of Digits: (status of call) The called party generates audible 
tones to indicate the status of the call (for example, Ringback, Busy, 
and Reorder).
Answer Supervision: (called party has answered) The called party 
indicates that the call has been answered. This signal is for billing 
purposes (Hotel/Motel), generation of SMDR reports, etc.
Disconnect Supervision: (release and go back to idle) Either party 
generates this signal to indicate the termination of a call and to return 
the trunk to the idle condition.