MJ-X Troubleshooting Guide AED-000025-04
Siemens T&D
LLC
7 version: 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).
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