2010ECL-NYC SERIES SIGNAL MONITOR
OPERATIONS MANUAL
Eberle Design Inc.
Page 29
Section 7
TROUBLE SHOOTING
SYMPTOMS:
Will not power on
CAUSES:
A)
Blown fuse
B)
Internal power supply is low
C)
No AC input to the monitor
SOLUTIONS:
A)
Remove the fuse and verify with an Ohm meter. Replace if necessary with
a fuse with the same current rating.
B)
Check the unregulated voltage across filter capacitor C78 with an
oscilloscope or volt meter. It should read approximately 170 Vdc when the
AC Line is equal to or greater than 110 Vrms. If the regulated supply (VDD)
is less than 4.5 Vdc the internal power supply monitoring circuit (U17) will
hold the MPU in reset and the DIAGNOSTIC indicator on the front panel
should illuminate. Measure the regulated voltage across capacitor C28. If it
measures lower than 5 _
+0.5 Vdc the regulated supply may be overloaded
or shorted to ground.
C)
If the fuse is not blown then the monitor may not be getting AC Line or
Neutral to the edge connector of the monitor.
SYMPTOMS:
Faults when AC power is applied
CAUSES:
A)
Program card is absent or not seated properly
B)
AC Line level is low
C)
Memory device fault
D)
No internal watchdog pulses
SOLUTIONS:
A)
The PCA indicator on the front panel will illuminate. Re-insert the program
card with the diode side of the card facing the front panel slot and depress
the RESET switch. The rear edge of the program card should be flush with
the front panel.
B)
Measure the AC Line voltage level with a volt meter. If it is below the
required "drop-out" level, the monitor will transfer the Output relay contacts
and enable the STOP TIME output to the controller. The AC POWER
indicator on the front panel will flash at a rate of 2 Hz to indicate the "brown-
out" condition.
C)
The memory devices are verified when AC Line power is applied or a Reset
command is issued. If a memory fault is detected the MPU executes a
STOP instruction. This causes all MPU activity to cease. Refer to Section
2.15.
D)
Absence of internal watchdog pulses may be due to the following
conditions: the MPU is not executing or completing the program loop or the
hardware to detect the internal watchdog pulses is not functioning. Place
an oscilloscope probe on U4.2. If there are no pulses, depress the front
panel reset switch to re-start the MPU. If the watchdog pulses are now
present on U4.2 then trace the remaining pulse detection hardware for the
required waveforms.
SYMPTOMS:
Required channels will not conflict
