Ohm, 20W resistor, by an angle bracket. The output of U17-2
is connected to the non-inverting input of differential amplifier
U18-3. Differential amplifier U18 will only amplify the differ-
ence between these two inputs.
ATURNONREQUESTswitchesQ15ONandapplies+5VDC
to R91. The output voltage of U17-2 will increase as the R91
heats up. The voltage will then stabilize as air flow passes over
both components.
Normal air flow in the transmitter will cause the voltage at
U18-1 to stabilize. If the air flow decreases, the temperature of
R91 will increase and U18-1 output will increase due to the
greater differential between inputs U18-3 and U18-2.
Thedifferencebetween the Ambient temperature sensorand the
output of the heated sensor is buffered and amplified by U18.
The AIR FLOW CAL is adjusted by R98.
S.2.3.2 Air Flow Fault Detectors
A two level fault comparator circuit is formed by U19. A
resistive voltage divider establishes voltages at the inverting
inputs of the comparators: +2.76 VDC at U19-4and +2.90 VDC
at U19-5. The non-inverting inputs U19-5 and U19-7 are con-
nected together.
The failure of one of the four fans or restricted air intakes will
cause the air flow voltage at TP11 to increase above the refer-
ence at U19-4 (2.76 VDC) and cause output U19-2 to go HIGH.
This will cause U19-13 to go from HIGH to LOW and illumi-
nateAIRFLOWREDUCED LED DS7. This logicHIGH is also
sent to the LED Board and will cause the AIR LED on the
ColorStat™ panel to changefrom GREEN (normal)toAMBER
(air flow reduced).
If the air flow voltage continues to rise, the air flow voltage will
increaseabovethe faultreferenceU19-5.TheoutputU19-1will
go HIGH and trigger the AIR FAULT on the LED Board. The
AIR LED on the ColorStat™ panel will turn from AMBER to
RED (fault).
S.2.4
Cable Interlock Monitor
Refer to Figure S-3 for the following discussion.
The CABLE INTERLOCKMONITOR functionis provided by
two series connections. Whenall theDriverModulesandDriver
Encoder cables are properly installed, a circuit is established
between J1-9 and J1-19 from Driver Modules D8 through D14
and between J2-9 and J2-19 from Driver Modules D1 through
D7. Both interlock circuits are identical. Therefore, only the
interlocks involving J2-9 to J2-19 will be discussed.
Due to the voltage divider action of R25, R26, R27, R28, and
R25, R31, R32 (through the interlock circuit), the voltage at
non-inverting input U7-11 will be greater than the voltage at
inverting input U7-10. Under these conditions, output U7-13
will be HIGH.
If the interlock J1-9 to J1-19 is not broken, U8-1 and U8-2
inputs will both be HIGH. With both inputs to NAND gate U8
HIGH, the output U8-3 will be LOW and Q14 will be turned
OFF.ThecollectorofQ14 will be HIGH dueto a pull-up resistor
on the Modulation Encoder.
If the circuit between J2-9 and J2-19 is broken (by removing
the encoder cable or unplugging a Driver Module), the voltage
at non-inverting input U7-11 will be lower than the voltage at
the inverting input U7-18 due to the additional voltage drop
provided by CR3. Under these conditions, U7-13 will go LOW.
With a LOW on either or both inputs of U8, output U8-3 will
go HIGH and turn on Q14. This will light the DRIVER CABLE
INTERLOCK LED DS8 and give a CABLE INTERLOCK
fault to the LED Board through the Modulation Encoder. The
CABLE INTERLOCK LED will illuminate on the ColorStat™
panel and the transmitter will turn OFF.
S.2.5
Power Supplies
Regulator U13 provides +15 VDC from the unregulated +22
VDC supply. When the +15 VDC is present, DS4 will illumi-
nate.The+15VDCsupply isfused by F01 andcanbemonitored
at TP7.
Regulator U14 provides +5 VDC from the unregulated +8 VDC
supply. When the +5 VDC is present, DS5 will illuminate. The
+5 VDC supply is fused by F02 and can be monitored at TP8.
Regulator U15 provides -5 VDC from the unregulated -8 VDC
supply. When the -5 VDC is present, DS6 will illuminate. The
-5 VDC supply is fused by F03 and can be monitored at TP9.
S.3 Maintenance
Refer to Section V of this manual for general printed circuit
board maintenance procedure.
S.4 Adjustment
Referto TuningandSetupProceduresin SECTION V,Maintenance.
Section S - Driver Encoder/Temp Sense (A19)
888-2297-002 S-5
WARNING: Disconnect primary power prior to servicing.
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