
MEP 660 - Trouble shooting Manual
Doc No.: IM – 51
Rev.2.0
Print: October 2008
25
PARAMETER
DESCRIPTION
FAULT CODE
1020
FAULT MESSAGE Rectifier Diodes HOT.
RESTRICTIONS
Engine RPM and Power Limited to 4th Notch.
ALARM BELL
30 Sec.
RESET LEVEL
Medium, Manual
After manual reset if the fault still present, the fault will be generated
again.
FAULT
RECOVERY
Automatic when thermostate switch in the power rectifier closes.
PROBABLE
CAUSES
1. The thermostate switch in the power rectifier unit is showing open
circuit due to blower might have failed resulting in high temperature
or the thermostate contact itself is open circuited permanently.
Note
: Probably this fault message will be logged in locomotives
equipped with self-cooled rectifiers and having thermal protection for
the diodes.
FAULT
ISOLATION
The thermostate switch is a normally closed interlock. 8 numbered
Green and Yellow LEDs on the digital input card MDIP-16 in slot 12
indicate the status of this interlock ‘RECT HOT’. Both Green and Yellow
LEDs should be ON in normal working condition of the loco. Reset the
message and check the status of both the LEDs
1. If both Green and Yellow LEDs are not ON, then
A. The power rectifier blower might have failed and the diodes
might have heated up. Check up proper working of rectifier
blower. If necessary replace the blower.
If blower had failed, please ensure that no diodes/fuses
are burnt out inside rectifier unit before releasing the
locomotive.
B. If the rectifier is cool and blower is working normal, then check
voltage at the rectifier terminal board on wire terminal No.
DLK1.
a) If the voltage is zero, check voltage on wire terminal 51.
1) If the voltage is zero, then 51-wire loop from CP/TB to
rectifier TB is open circuited. Check and replace.
2) If the voltage is > 65V, the thermostae switch is
defective or internal wiring is burnt. Check up with
rectifier and attend.
C. If the voltage is > 65V, check voltage at terminal DLK1 on
backside TB.
a) If the voltage is zero, then the wire loop DLK1 from backside
TB to Rectifier TB is open circuited. Check and replace.
D. If the voltage is > 65V and
a) The 8 numbered Green LED on the Digital Input card in slot
12 is not ON, then the wire loop from backside TB to MEP-
660 is open circuited. Check and replace.
b) Green LED is ON and 8 numbered Yellow LED on the digital
input card in slot 12 is OFF, then the digital card is defective.
Check and replace.