Siemens MJ-X User manual

MJ-X
Troubleshooting Guide
Siemens Power Transmission & Distribution
Proprietary Information
[AED-000025-04]
Revision History
Document Revision 04:5January 98-
Document number (AED-000025-04) added.
Document Revision 03: 14 July 97 -
This document was created from an original troubleshooting guide (dated May 93).

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 2version: 5 January 1998
1. Troubleshooting the MJ-X
This document outlines a process for preliminary troubleshooting of the MJ-X. The major objectives are:
1. determine if the fault resides at the MJ-X
2. check for improper jumper arrangements or other easily correctable conditions
3. check for field/customer repairable fault (e.g., bad fuse or Neutralite bulb)
4. If necessary, document problem details for factory repairs.
2. Basic Approach
For efficient troubleshooting, the following basic approach is recommended.
1. Verify configuration (hardware & software.)
2. Make sure the control panel hardware & software support the feature(s) you want to use.
3. (Consult MJ-X software revision documents.)
4. Substitute a known good panel. Check if it duplicates the symptoms. If so, the problem is more
likely with the system or wiring rather than with the MJ-X. (This is not always the case.)
5. Use this troubleshooting guide to isolate and fix the problem if possible. If field fix not feasible,
document problem in detail for factory repair.
The following assumes you are familiar with both the MJ-X operation and the MJ Suitcase Simulator. For
further information on these topics, refer to the appropriate user manuals. You also need to be familiar
with safety procedures for electrical and electronic equipment.
3. Test Equipment
Siemens recommends the following test equipment: 1) MJ suitcase simulator, 2) True RMS Volt/Amp
meter, and 3) PC running MJXplorer.
If using the MJ suitcase tester, connect to the PDS ("jack plug") cable. [As an alternative, provide a
nominal 120VAC at the external power banana plugs and a 0-200 mA current source at the PDS C2/E1.]
Unless otherwise noted, tests are performed with U2 and P2 at 120 VAC. [E must be connected to E1 at
the PDS if the suitcase tester is used for these tests.] {Caution: If using external power, be aware that
several of the PDS connections are hot.}
For tap motor direction sensing with the MJ-X, the “J” and “K” jack plug signals must have a minimal
resistive load. If you’re not using the MJ simulator, connect load resistors (2.2K 10W) from J to E and K
to E at the PDS (jack plug).
3.1. MJ Simulator Overview
The MJ suitcase simulator provides the following test capability: variable voltage sources (for U2 and P2),
variable current source (for C2), toggle switch for Straight/Inverted regulator simulation, toggle switch for
Inverted Source Side Potential Transformer (SSPT), Neutralite test button, Operations Counter test button,
Drag Hands Reset indicator, “J” (Raise) indicator, and “K” (Lower) indicator. With the MJ suitcase
simulator, you can simulate forward & reverse power flow, and leading/lagging power factor.
When pressed, the Neutralite and Operations Counter buttons ground (short to “E”) the jack plug signal
U12 and U10, respectively. Otherwise, these signals are open. The Drag Hands Reset Indicator lights
when the Drag Hands Reset signal (jack plug U11) has a nominal 120VAC. The “J” indicator lights
when the jack plug “J” signal has a nominal 120VAC. The “K” indicator lights when the jack plug “K”
signal has a nominal 120VAC.

MJ-X Troubleshooting Guide AED-000025-04
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MJ Simulator Voltage Source Connections:
Straight/Inverted
Switch Inverted SSPT Switch “L” Voltage Source Connection “S” Voltage Source Connection
Straight Doesn’t matter Jack plug “P2” Jack plug “U2”
Inverted INV SSPT Jack plug “U2” Jack plug “P2”
Inverted Off Jack plug “U2” none
Toggling the Power Flow Switch from Forward to Reverse changes the voltage-to-current phase
relationship from in-phase to 180°out-of-phase, respectively.
For tap motor direction sensing with the MJ-X, the MJ simulator must include load resistors (2.2K 10W)
from J to E and K to E. Check if your MJ simulator has these resistors. If your simulator lacks these
resistors, add them.
4. Jumper Tables
Make sure standard jumpers for both the power and main processor boards are in place for testing. See
tables below.
Power Board Jumper Table
Jumper
Designation Jumper Connection Jumper Type Jumper Location Jumper Purpose
JP401 "+P" to "BAL" ("E" gnd) T.B. J405 1-2 For connecting balancing winding
JP402 "C" to "C2" T.B. J409 1-2 For connecting external current
meter
JP414 "U" to "U6" T.B. J405
10-11 For external control over tap motor power signals
JP415 "U6" to "U7" T.B. J405
12-13 For external control of power for MJ-X's (Auto) Tap Control Relays
JP416 "J21" to "J22" T.B. J405 4-5 For external control of (Auto) Raise
signal ("J") path
JP417 "K21" to "K22" T.B. J405 8-9 For external control of (Auto) Lower
signal ("K") path
(J402),
(J410) External Source to Power Switch 2 pin header J402, J410 For connecting an external source of "External Power" to SW403
(J408) (Version N power boards
only) Auto Inhibit Input:
pulsed or latched
3 pin
header J408:2-3 (pre-prod.
default)
Auto Inhibit Input. For latched: use
J408:2-3. For pulsed: use J408:1-2.
(Version N power boards only)

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Main Processor Board Jumper Table
Jumper
Location Jumper Type Jumper Position Jumper Purpose
J104 pins
6&8 part of 24 pin
header
IN (SW
Vers.2.03)
Out (SW
Vers.2.10 & up)
Connects DSACK0- to ground. (Indicates to uP that the data
bus is 8 bits rather than 16 bits.) This jumper needs to be
removed for connecting the test connector (J104) to the
Background Debug Mode (BDM) cable/interface.
J110 3 pin
header 2-3 1-2: For 128K x 8 Boot Flash device (28F001) at U2. 2-3: For 256K x 8 (any type) device (e.g., 28F020) at U2.
J111 3 pin
header 2-3 1-2: For 128K x 8 Boot Flash device (28F001) at U2. 2-3: For 256K x 8 (any type) device (e.g., 28F020) at U2.For
J113 3 pin
header 1-2 1-2: For 128K x 8 (or 32K x 8) Static RAM device at U3. 2-3: For 512K x 8 Static RAM device at U3.
J115 3 pin
header 1-2 1-2: Reset not asserted. 2-3: Reset asserted. (Connect this momentarily only.)
J116 2 pin
header IN Connects D0 to pull down resistor. This connection is also made with a trace on the circuit board for pre-production MP.
J117 2 pin
header OUT Connects AGND to (digital) GND. Useful when testing MP board by itself.
J118 2 pin
header OUT Allows for a remote speaker to be used instead of the on board speaker. (If remote used, remove on board speaker.)
J119 2 pin
header OUT Connects (digital) GND to chassis, for protection.
J120 2 pin
header IN For pre-production MP boards (version “0P”) only.
Connects data port connector shell to chassis, for protection.
J121 3 pin
header 1-2 1-2: For (local) data port wired as a "DCE". 2-3: For (local) data port wired as a "DTE".
J122 3 pin
header 1-2 1-2: For (local) data port wired as a "DCE". 2-3: For (local) data port wired as a "DTE".
J123 2 pin
header IN For connecting DCE output handshake signals to local port data connector (J106). (Out for DTE application.)
Unless otherwise noted, AC voltages are measured referenced to AC return ("E"). DC voltages are
measured reference to logic ground (GND). The logic ground is necessarily dc-isolated from the AC
return. Avoid connecting the logic ground to “E” or any other AC signals.
Note: The (local) data port should be jumpered as "DCE" for connecting to a terminal device (such as a
notebook or laptop computer) when using a straight-through cable. The (local) data port should be
jumpered as "DTE" for connecting to a modem when using a straight-through cable. Refer to MJ-X
Application Note 5 for further information.
5. Symptom Based Troubleshooting
Apply power and determine trouble symptom. Use Troubleshooting Symptom Tables below. [Find the
symptom that most completely describes what you are observing.]
Using MJXplorer, save the present MJ-X configuration and load “default” configuration.
To troubleshoot, use “known working” Power Board, Main Processor (MP) board, and MJ-X overlay. To
isolate faults, substitute the known good board/assembly. Make sure the "known good" board/assembly
has correct jumpering and configuration.

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 5version: 5 January 1998
5.1. Troubleshooting Overview
Notes
1. Caution: Disconnect power source when removing cover. Observe ESD and safety precautions when performing checks.
2. To isolate a problem, substitute “known good” component (i.e., board assembly, device, or part) and check operation.
3. Refer to Instruction Manual for operating details.
4. For Any “Open Box” troubleshooting, always perform “Not Powering Up—Open Box” checks.
5. Check if 16-pin Terminal Block is seated and its jumpers are secure.
Symptom “Closed Box” {Perform these first} “Open Box”
Not Powering Up qPower Switch in correct position?
qBlown Power and/or Sensing fuses?
qBlown External Source fuse?
qIf used, PDS (jack plug) connected properly?
qTerm. Block (16-pin) seated and jumpers secure?
qGood power source (80-140 VAC)?
>> See Note 4 & “Open Box”.
qPROM oriented/seated correctly (no bent pins)?
qConnectors mated/seated/oriented properly?
qSocketed parts oriented/seated properly?
qFuse connectors mated properly?
qJumpers in correct positions?
qComponents sheared off or missing?
qCharred/damaged parts or circuit board area?
>> Isolate to Power or MP board.
Displays Incorrect or
no Characters See Note 4 & “Open Box”. qDisplays (DS1&DS2) seated properly in sockets? >> Isolate to Display Devices or “other” (MP board).
Indicator(s) won’t light
(or won’t turn off)
qLEDs turn on in-sequence at power-up?
Noàprobable overlay failure. YesàLikely MP fault.
>> See Note 4 & “Open Box”.
qConnector J102 mated/seated/oriented properly?
qOverlay cable damaged or cut?
>> Isolate to Front Panel Overlay or MP board.
Keypad fault qSome keys work?
Yesàprobable overlay failure.
>> See Note 4 & “Open Box”.
qConnector J102 mated/seated/oriented properly?
qOverlay cable damaged or cut?
>> Isolate to Front Panel Overlay or MP board.
No Source Voltage q“Type” configured correctly? Blown Sensing Fuse?
>> See Notes 4&5. >> Isolate to Power or MP board.
Calibration Off > 2%
(incorrect metering)
qConfiguration settings correct (U2, P2,C2 ratios)?
>> See Notes 4&5. >> Isolate to Power or MP board. Calibrate if needed.
Cycles “Testing…” qGood power source (80-140 VAC)? See Notes 4&5. >> Isolate to Power or MP board. Calibrate if needed.
Tap won’t Raise/
Lower in Auto/Remote
qTerm. Block (16-pin) seated and jumpers secure?
qAuto Inhibit active? Low Current Inhibit active?
Set MJ-X R/A/M switch to Remote. With MJXplorer, perform
“Raise/Lower”. Verify J/K signal activates.
>> Isolate to Power or MP board.
>> Verify Solid State Relay. (Substitute known good part.)
Won’t Raise/Lower in
Manual PDS J/K go active for Manual Raise/Lower attempt? >> See Notes 4&5.
qSwitches SW401& SW402 functional?
Drag Hands Reset
(DHR) Failure
qWhen DHR switch on, U11 has nominal 120VAC?
>> See Notes 4&5.
qSwitch SW404 functional?
Voltage Cal.
Terminals: No voltage For Inverted Reg.s w/o SSPT, there is no “P2”voltage”. >> See Notes 4&5.
qU2/P2 Switch (SW405) functional?
“Neutralite” off at
Neutral
qNeutralite illuminates with Neutralite Test Switch?
Noàprobable bad bulb. Yesàcontinue.
qClosing PDS-U12 to E illuminates indicator?
If no, probable power board fault. >> See Notes 4&5.
q“Backdoor” Mode Neutralite Test good?
Tap position incorrect
(See Notes 4&5.)
qSet MJ-X R/A/M switch to Remote. With MJXplorer,
perform “Raise/Lower”. Raise/Lower sensing OK?
qConfiguration error?
q“Backdoor” Mode Op Count Test good?
q“Backdoor” Mode Neutralite Test good?
Operations Counter not
incrementing
(See Notes 4&5.)
qClosing PDS-U10 to E increments Operations Count?
Yesàconfiguration error? NoàSee “Open Box”.
q“Backdoor” Mode Op Count Test good?
q“Backdoor” Mode Neutralite Test good?
>> Isolate to Power or MP board.
Data Port not
communicating
qConnect data port loopback (pins 2 & 3 shorted).
qRun “Backdoor Mode” Data Port Loopback test.
FailsàSee “Open Box”. PassesàCheck external cabling.
Verify internal MJ-X jumpers.
qVerify data port jumpers (J121-123).
>> Isolate to MP board.
Auto Inhibit Input
(T.B.) won’t work
q“Backdoor” Auto Inhibit input Test good?
Configured correctly? See “Open Box”. >> Isolate to Power or MP board.
Auto Inhibit Output
(T.B.) won’t work
qConfiguration error? qConnect “wetted” load to verify.
>> Isolate to Power or MP board.
Term. Block VRC
won’t work
q“Backdoor” VRC input Test good?
qConfigured correctly? Auto Inhibit inactive?
q“Backdoor” VRC input Test good?
>> Isolate to Power or MP board.
Time/Date incorrect qTime/Date needs resetting? Battery low?
q“Backdoor Mode” Real Time Clock test good?
q“Backdoor” Mode Battery Test > 2.4V?

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 6version: 5 January 1998
6. “Alert” Based Troubleshooting
Diagnose system and control panel problems using the Alert Messages and the table below. Rule out
“Normal Causes” first. Troubleshoot starting with “Problem Causes” and “What to Check”.
System transients may produce MJ-X Alert messages. If possible, determine if this is the case before
proceeding with an in-depth troubleshooting effort.
Alert
Name Normal Causes Problem Causes What to Check
(Rule out “Normal” causes first!)
Low
Current Load current < low current threshold (cfg.) Bad C/C2 connections; MJ-X circuit failure Caution: Keep current circuit “Closed” while connected to regulator. Measure C/C2 current. Check C/C2 Terminal Block
jumper. Check E1 and C2 wiring. Calibrate the current.
Auto
Inhibit Auto Inhibit active via Term. Block or communications Bad AutoInhibit input contacts; MJ-X circuit failure Perform backdoor-mode test on Auto Inhibit input contacts.
Tap Track
Error Incorrect tap tracking configuration,
MJ-X needs to sense Neutral
Bad regulator signals (U10,
U12); MJ-X circuit failure (J,K,
U10, U12 sense)
Perform backdoor-mode test on these signals.
Neutral
Sig. Err Incorrect tap tracking configuration Bad regulator signal (U12); MJ- X circuit failure (U12 sense) Check the Neutral (PDS-U12) and Operations Counter (PDS- U10) inputs using Backdoor-Mode test.
Tap Pos
???? Incorrect tap tracking configuration,
MJ-X needs to sense Neutral
Bad regulator signals (U10,
U12); MJ-X circuit failure (J,K,
U10, U12 sense)
May indicate a temporary fault condition (failure to detect a
transition within the allowed time window on one of several input
lines.) Check the Neutral (PDS-U12) and Operations Counter
(PDS-U10) inputs using Backdoor-Mode test. If necessary,
substitute in the "known good" power board to isolate the problem
to the faulty (board) assembly.
Low PT
Thresh Load Voltage < PT threshold (cfg.) MJ-X circuit failure (U2/P2 voltage sense circuits) This alert does not (necessarily) indicate an MJ-X fault condition. Check to see if this alert condition goes away when both U2 and
P2 are above the (configurable) PT Threshold. If condition
persists, try substituting in the "known good" power board to
isolate the problem to the faulty (board) assembly.
Over
Current Load current > over current threshold (cfg.) This alert does not (normally) indicate an MJ-X fault condition. Check to see if this alert condition goes away when an in-range
current (0-200 mA) is applied at C2/E1. If condition persists, try
substituting in the "known good" power board to isolate the
problem to the faulty (board) assembly.
NV RAM
Reset PROM update. Electrical transient causes loss of Static RAM data. (Log &
min/max data lost.)
May indicate a temporary fault condition. If condition appears
repeatedly, consult factory. Additional surge suppression may be
required for your installation.
Low
Battery Battery needs replacing. MJ-X circuit fault (on MP board.) Indicates that it is time to replace the Lithium Battery (on the MP board.) If condition persists after a good battery is installed,
check that the battery was installed properly. If fault persists,
substitute "known good" Main Processor board to isolate the
problem.
High
Voltage Load Voltage > high voltage threshold (145 VAC) MJ-X circuit failure (U2/P2 voltage sense circuits) May indicate a temporary system fault condition. If condition persists when in-range voltages (90-140 VAC) are applied to both
PDS-U2 and PDS-P2 inputs, perform calibration and input
voltage test. If condition persists, try substituting in the "known
good" power board to isolate the problem to the faulty (board)
assembly.
Not In
Auto Remote/Local-Auto/Local Manual (R/A/M) switch not in
Auto
MJ-X sensing for R/A/M Switch
inoperative; defective switch Substitute "known good" power board to isolate the problem to the faulty (board) assembly. Check R/A/M switch operation.
R Limit
Reached Tap position reaches MJ-X Raise Limit (cfg.) See “Tap Pos ??” Alert See “Tap Pos ??” Alert
L Limit
Reached Tap position reaches MJ-X Lower Limit (cfg.) See “Tap Pos ??” Alert See “Tap Pos ??” Alert
Self Test
Fault PROM programmed incorrectly. Bad RAM. Replace PROM. If problem persists, substitute "known good" Main Processor board to isolate the problem.
Pseudo
Manual Remote communications control in effect. Replace PROM. If problem persists, substitute "known good" Main Processor board to isolate the problem.

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 7version: 5 January 1998
7. Voltage and Current Calibration
Connect an external true RMS meter at the test point(s) for the signal. Apply the nominal calibration
voltage or current (per the table). Display the corresponding MJ-X calibration screen; (view these under
the <DIAGNOSTICS> menu.) Press the change key, then the up or down arrow to get the displayed
value to match the external meter value, then press the Save key.
Signal to
Calibrate Test Signal Application
Point
Test Signal
Measurement
Point
Nominal
Calibration Signal
Magnitude
MJ-X
Calibration
Screen
Conditions
U2 PDS -- U2 Voltage Test
Terminals 120 VAC (RMS) U2 Cal SW405 = U2
P2 PDS -- P2 Voltage Test
Terminals 120 VAC (RMS) P2 Cal SW405 = P2
ILO PDS -- C2 to E1 C/C2 (J409- 1&2) 10 mA (AC RMS) ILO Cal
IMED PDS -- C2 to E1 C/C2 (J409- 1&2) 80 mA (AC RMS) IMED Cal
IHI PDS -- C2 to E1 C/C2 (J409- 1&2) 200 mA (AC RMS) IHI Cal
8. MJ-X Self Tests
At start up, the MJ-X performs several self-tests, including: LED Indicator test, RAM read/write, and
PROM checksum.
The start-up LED Indicator test flashes all front panel LEDs three times. If one or more fail to flash, this
indicates a problem with the overlay, the overlay cable/connector, or the MJ-X Main Processor board.
The start-up RAM read/write test verifies the MJ-X non-volatile static RAM without effecting RAM-
stored non-volatile data (e.g., log and min./max. data). RAM failures produce varying symptoms. For
complete failure, the MJ-X program will not run, and the MJ-X will appear “dead” with the exception of
display flickering when you power it. For loss of non-volatile data, the MJ-X clears all RAM-stored non-
volatile data, and reports this in the Alert message “NV RAM Reset”. The MJ-X also displays the “NV
RAM Reset” alert message when the MJ-X detects a program memory (PROM) update or a checksum
error.
The MJ-X continuously runs PROM self-tests and reports the results in the <Diagnostics> menu
“Checksum” screen. MJ-X reports the checksum as “Pass” or “Fail”. A failed checksum indicates a
problem with the PROM.
9. MJ-X Internal Power Supply Signals
If you suspect an internal supply problem, verify the MJ-X power supply circuits per these specifications:
PDS-U2 VDC_U
(J403-7) VDC_U (J403-7) VCC (J403-13) VCC (J403-13) VISO1+ (J411-1) VISO1+ (J411-1) VISO2+ (J411-3) VISO2+ (J411-3)
Vac min vdc max vdc min vdc max vdc min vdc max vdc Min vdc max vdc
90 14 20 4.75 5.25 8 15 8 15
145 32 40 4.75 5.25 18 25 18 25
Note: VISO1+ measured referenced to ISO1GND (J411-2). VISO2+ measured referenced to ISO2GND
(J411-4). VCC and VDC_U are measured referenced to (digital) ground (J403- 5&6).

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 8version: 5 January 1998
10. Backdoor Tests
Enter the “Backdoor Test” mode as follows:
1. For MJ-X Main Processor software versions prior to 2.30: Adjust input voltage or the MJ-X Voltage
and Bandwidth setpoints to achieve an in-band condition—i.e., deactivate J and K outputs.
2. Display the "Data Stat = XXXX" screen under the <COMMUNICATIONS> menu.
3. Set the Remote/Auto/Manual (“R/A/M”) Switch to Remote and the U2/P2 Switch to U2.
4. Press the following keys in the order listed: Left Arrow, Right Arrow, Left Arrow, Right Arrow, +/-.
While in the backdoor test mode, the Alert LED blinks continuously (at a slower rate than for the normal
product code.) Cycle the power or perform the watchdog test to exit the Backdoor Test mode.
10.1. “Backdoor” Tests
When entering the backdoor test mode, the MJ-X runs automatic checks and displays diagnostic messages
if appropriate. The MJ-X displays: "Test Code XXXXXX", where XXXXX is the backdoor test date code.
Keypad Test
Set the Remote/Auto/Manual (“R/A/M”) switch to Remote or Manual. Press any key. The MJ-X displays
the key’s name. Press the same key multiple times. The MJ-X alternately displays the key name and a
blank screen.
Remote/Auto/Manual Test
Toggle the Remote/Auto/Manual switch. The MJ-X displays the active switch position. For “AL” series
MJ-X units only: With the R/A/M switch in the Manual position, toggle the Tap Raise/Lower switch. The
MJ-X displays the Tap Raise/Lower switch position.
Indicator LEDs Test
Set Remote/Auto/Manual (“R/A/M”) switch to Manual. Set Tap Raise/Lower switch to Lower. The
Overlay LEDs (except Alert) turn on sequentially from top to bottom. The Alert LED blinks
independently at a regular rate. [This test may not always work. Use the Power-on LED test as a
substitute.]
Neutral Sense
Short the Neutralite signal (jack plug U12) to “E”. The MJ-X displays "Neutral Pos ON". Remove the
“E” ground connection. The MJ-X displays "Neutral Pos OFF".
Operations Counter Sense
Short the Operations Counter signal (jack plug U10) to “E”. The MJ-X displays: "Op Counter ON".
Remove the “E” ground connection. The MJ-X displays "Op Counter OFF".
VRC1(2) and Auto Inhibit Sense Test
Short the VRC1(2) terminals. The MJ-X displays "VRC En1(2) ON". Remove the short. The MJ-X
displays "VRC En1(2) OFF". Short the Auto Inhibit terminals. The MJ-X displays " Auto Inh ON".
Remove the short. The MJ-X displays " Auto Inh OFF".
Display Test
[Set the Remote/Auto/Manual switch to Auto. Press the Bandwidth key.] Turns on all segments, writes
test screens, changes brightness, then blanks the character display. This test continues until the
Bandwidth key is pressed again or some other key is pressed.
Speaker Test
[Set the Remote/Auto/Manual switch to Auto. Press the Voltage Level key.]

MJ-X Troubleshooting Guide AED-000025-04
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Turns on speaker driver with audio tone. (~ 2 seconds)
Battery Level Test
[Set the Remote/Auto/Manual switch to Auto. Press Time Delay.] Displays MJ-X battery voltage.
Local Port (SCI) Loopback Test
[Connect a loopback cable/connector (pins 2 & 3 shorted) to the MJ-X data port. Set the
Remote/Auto/Manual switch to Auto. Press the Alert key.] The MJ-X sends a canned message out the
data port and verifies that the same message is received back.
Reset Status Register
[Set the Remote/Auto/Manual switch to Auto. Press the Voltage Limit Control key.]
The MJ-X reads its MPU reset status register and displays the reset type, abbreviated as: "X" = external,
"P" = power up, "W" = watchdog, "H" = halt, "C" = loss of clock, "S" = system, and "T" = test module.
The reset types that will normally be observed include "X", "P", and "W". Other types may indicate a
problem with the MJ-X. [MJXplorer also reads/displays the Main Processor Reset Status Register.]
Watchdog Test
[Set the Remote/Auto/Manual switch to Auto. Press the Operations Counter key.]
The MJ-X discontinues updating the “watchdog timer”, forcing a reset. After resetting, the MJ-X resumes
normal product operations (i.e., the backdoor test mode is exited upon reset.)
Serial EEPROM (“SEEP”) Write/Read Test
[Set the Remote/Auto/Manual switch to Auto. Press the Cancel/Reset key.]
The MJ-X performs a non-destructive read/write test of the Serial EEPROM. Several memory locations
are written and then read back. The MJ-X reports Pass/Fail results.
Serial EEPROM (“SEEP”) Read Only Test
[Set the Remote/Auto/Manual switch to Auto. Press the Change or Save key. See below.] The MJ-X
reads/displays the values stored at a particular address within the SEEP.
If the Change key is pressed first (to initiate the SEEP read test), the SEEP read address starts at 20 (hex).
If the Save key is pressed first (to initiate the SEEP read test), the SEEP read address starts at 30 (hex).
Subsequently, pressing the Change key increments the SEEP address by 1. Pressing the Save key
increments the SEEP address by 16 (10 hex).
Serial EEPROM (“SEEP”) Erase
[Set the Remote/Auto/Manual switch to Auto. Press the Max/Min key. The MJ-X requests confirmation
before proceeding. Be sure you want to do this! Write down the settings for “MP BD VERS” and “PWR
BD VERS” before proceeding!]
The MJ-X re-initializes its configuration data to default values for whatever MP software version is
loaded into the program memory. After erasing, verify all configuration data. Restore the settings for
“MP BD VERS” and “PWR BD VERS”.
Real Time Clock (RTC) Tests
Note: For all RTC tests, set the Remote/Auto/Manual switch to Auto. Press key indicated in “[ ]”.
Read/Write: [Reactance] Reads/writes the RTC Control register. The MJ-X reports pass or fail.
Clear RTC Power Sense: [Menu] This performs no meaningful function.
Enable RTC Power Sense: [Up Arrow] This performs no meaningful function.
Status Register Read: [Down Arrow] The MJ-X displays the hex value for the RTC Status Register.
Interrupt Register Read: [Left Arrow] The MJ-X displays the hex value for the RTC Interrupt Register.
Control Register Read: [Right Arrow] The MJ-X displays the hex value for the RTC Control Register.

MJ-X Troubleshooting Guide AED-000025-04
Siemens T&DLLC 10 version: 5 January 1998
11. “Backdoor Mode” Summary
1. For MJ-X Main Processor software versions prior to 2.30: Adjust input voltage or the MJ-X Voltage
and Bandwidth setpoints to achieve an in-band condition—i.e., deactivate J and K outputs.
2. Display the "Data Stat = XXXX" screen under the <COMMUNICATIONS> menu.
3. Set the Remote/Auto/Manual (“R/A/M”) Switch to Remote and the U2/P2 Switch to U2.
4. Press the following keys in the order listed: Left Arrow, Right Arrow, Left Arrow, Right Arrow, +/-.
Backdoor Test How to Start Conditions Expected Results
Auto Inhibit Sense Short or Open Term. Block
contacts. “Remote Auto Inhibit” Indicator turns on when
contacts closed
Display toggles from “AutoInh On” to “AutoInh Off”
Battery Level Press Time Delay Key. R/A/M in Auto. Displays battery level. (Good battery reads > 2.4V)
Data Port (Loop Back test) Press Alert Key. R/A/M in Auto. Pins 2&3
shorted for looping back. Displays pass/fail results for data port test (is transmitted message received back?)
Display Press Bandwidth Key. R/A/M in Auto. Turns on all segments, writes test screens, changes
brightness, then blanks the character display. Repeats.
Indicator LEDs Raise/Lower switch in
Lower. R/A/M in Manual. Tap Raise/Lower in Lower. The Overlay LEDs (except Alert) turn on sequentially from top to bottom.
{The Alert LED blinks independently at a regular
rate.}
Keypad Press any key. R/A/M in Manual. MJ-X displays key name. Alternately blanks for
multiple keypresses.
Neutral Sense Close/Open jack plug “U12”
to “E”. Display toggles from “Neutral Pos ON” to “Neutral Pos OFF”
Operations Counter Sense Close/Open jack plug “U10”
to “E”. Display toggles from “Op Counter ON” to “Op Counter OFF”
Remote/Auto/Manual
Switch Toggle R/A/M switch. MJ-X displays the switch position.
Real Time Clock (RTC)
Read/Write Press the Reactance Key. R/A/M in Auto. Displays pass/fail results of RTC test
Reset Status Register
[MJXplorer also
reads/displays the MJ-X
Main Processor Reset Status
Register.]
Press the Voltage Limit
Control key. R/A/M in Auto. Displays last reset type: "X", "P", and "W" are normal. Others may indicate an MJ-X problem. [X=external,
P=power up, W=watchdog, H=halt, C=loss of clock,
S=system, and T=test module.]
Serial EEPROM Erase
Caution! Causes loss of
stored configuration data.
Press the Max/Min key.
{MJ-X request confirmation} R/A/M in Auto. Write down “MP BD VERS” and “PWR
BD VERS” before
proceeding!]
Re-initializes configuration data to defaults for
whatever MP software version is loaded into the
program memory. After erasing, verify configuration
data. Restore settings for “MP BD VERS” and “PWR
BD VERS”.
Serial EEPROM Read Only Press Change or Save to start.
Subsequent Change key
presses increment the address
by 1. Pressing the Save key
increments the (hex) address
by 16.
R/A/M in Auto.
Pressing Change first initiates
the read address to 20 (hex).
Pressing Save first initiates the
read address starts to 30 (hex).
Displays Serial EEPROM binary data.
Serial EEPROM
Read/Write Press the Cancel/Reset key. R/A/M in Auto. Displays pass/fail results of non-destructive Serial EEPROM read/write test.
Speaker Press the Voltage Level key. R/A/M in Auto. Turns on speaker driver with audio tone. (~ 2 seconds)
Tap Raise/Lower Toggle Raise/Lower Switch. R/A/M in Manual. For AL series units ONLY, the MJ-X displays Tap
Raise/Lower switch position.
VRC1, VRC2 Short or Open Term. Block
contacts. Display toggles from “VRC EnN ON” to VRC EnN OFF” (where N = 1 or 2)
Watchdog Press the Operations Counter
key. R/A/M in Auto. MJ-X forces watchdog reset, exits Backdoor mode.
Unused tests: (all with R/A/M in Auto)
Clear RTC Power Sense—Menu key, Enable RTC Power Sense—Up Arrow key, RTC Status Register Read—Down Arrow key, RTC
Interrupt Register Read—Left Arrow key, RTC Control Register Read—Right Arrow key.
************** These need to be included in the next update: ***********************
Fault Isolation for:
qExpansion Rack
qCommunications Module