VC3500/VC3700 Troubleshooting Manual
Valco Cincinnati
Page 22
EPC Board - 151xx379
(Reference Schematic 999xC151-209)
Service Access Points
Connectors
J1
Connection for 12vdc power supply, input analog signal, Intake output
signal, and Exhaust/Sensor output signal.
Indicators
CR1 (12v Supply) When lit, this green LED indicates that the 12 vdc supply voltage is
available.
CR2 (Intake)
When lit, this yellow LED indicates that the Intake solenoid is active.
CR3 (Exhaust)
When lit, this yellow LED indicates that the Exhaust solenoid is active.
Jumpers
JP1 (E/S Out)
Output Signal Select
Pins 1 & 2 jumpered: Makes the E-OUT signal available at J1, pin 5,
allowing an external device to monitor the
Exhaust
solenoid
condition.
Pins 2 & 3 jumpered: Makes the S-OUT signal available at J1, pin 5,
allowing an external device to monitor the Sensor (transducer) analog
signal.
Potentiometers
P1 (Span)
Provides adjustment of transducer signal gain, allowing an anticipated
small transducer excursion to effect a full scale (0 to 12v) change at
TP2.
P2 (Zero)
Provides adjustment for nulling the pressure transducer signal at zero
pressure.
P4 (Gain)
Not installed on later models. Provides adjustment of feedback loop
gain and affects the hysteresis (and frequency) for switching the Intake
and Exhaust solenoids.
Schematic Description
Diode D1 protects the circuit from applying the 12 to 24vdc supply in reverse polarity.
Voltage regulator U2 provides a ground reference for the LM324 Op Amps and is 0.7vdc
lower than the ground reference supplied by U4 for the analog signals. This difference is due
to D2. Voltage regulator U4 provides a 12v supply for the LM324 Op Amps and is 0.7vdc
higher than the 12vdc generated by U2 for the analog signals. This scheme allows for quasi
“rail-to-rail” Op Amp output signals.
Op Amp U5, output pin 7, buffers the input command signal.
U1 (LM334) is a current source that provides a constant current source for the pressure
transducer.
Op Amp U3, output pins 7 & 8, buffers the pressure transducer signal and offers some gain
adjust with the SPAN pot (P1). Op Amp U3, output pins 1 & 14, provides zero adjustment
with the ZERO pot (P2).
Summary of Contents for VC3500
Page 1: ...VC3500 User s Manual Software Version 3 X Manual Number MCO35 Manual Release Date July 1999 ...
Page 19: ...Installation VC3500 User s Manual Valco Cincinnati 16 Figure 8 Internal Connections Diagram ...
Page 88: ...VC3700 User s Manual Software Version 3 X Manual Number MCO34 Manual Release Date July 1999 ...
Page 181: ...VC3500 VC3700 Troubleshooting Manual Manual Number MC048 Release Date May 1999 ...
Page 185: ...VC3500 VC3700 Troubleshooting Manual Valco Cincinnati Page 1 System Level Documents ...