MULTISKAN
FILTER OUT OF POSITION TOLERANCE
Reason:
Thecalculated filter position and
fi
lter home position signalled by filter sensors
are
too far apart.
Action: Open the instrument cover and power up the instrument. Watch filter movement
d&ng startup. If the filter stepper loo&s steps it can be noticed and also heard.
In this caselook for something that mechanically disturbs freemovement of the
filter wheel.
Service:
If no mechanical reason for irregular filter movement is found, first check that
+21V voltage from the power supply is ok.
Then continue by checking pins 29 and 33 of D1 on the MUSCU-RC board.
Power up the instrument. Pin 29 should be high when the filter is stopped and
low when the filter is running. At pin 33 there should be short active high pulses
whenever the filter or plate stepper is running. If the signals are not okay,
disconnect connector
X7
and power up again. If the signals still are not okay,
D1 is faulty. Else either N1 or N4 on MOTCU board is faulty. To determine
which one requires quessing or cutting traces to one of the chips.
If the signals at pins 29 and 33 of D1 were ok, the fault remains in one of N4,
V6 to V10 and R19 on MOTCU board or the filter stepper itself.
If this error is reported though the filter wheel seems to rotate smoothly, there
may
be
a problem in sensing the filter home position. Filter home position
sensors are enabled only while the filter stepper is running. The enable signal
originatesfrompin
8
of Dl on theMUSCU-RC board and is active high. Home
position isdetected from pins 34 and 36of D1 being simultaneously low. When
the filter is stopped, theenable signal shouldbe low and both sense signals high.
If not, disconnect connector
X7
on MUSCU-RC. If the signals still are in
incorrect states, Dl on MUSCU-RC is faulty. Else the problem is on MOTCU
board or the sensors themselves. Connect
X7
and power up the instrument.
Observe the enable signal during startup sequence. It should be high when the
filteris rotating andlow when the filter is stopped. If not, buffer Dl on MOTCU
-
.
.
board is faulty.
Disconnect connector X4 on MOTCU board. Both sense signals on pins 34 and
36 of Dl on MUSCU-RC board should
be
steady high. If not, buffer Dl on
MOTCU board is faulty.
Document
Release
,r,
Section Page
351/352-100-~
1
.O
-<--
Labsystems
8
15
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