6 TROUBLE SHOOTING
The MCU system is supplied fully tested, and it is unlikely that any apparent faults are as a result
of faulty hardware. Most problems encountered are as a result of installation faults or incorrect
software/hardware configuration.
6.1 Common Faults
Fault
The Detector head display is blank.
• Ensure the MCU has power connected.
• Ensure the current loop connections are correct at the detector head and at the MCU.
• Ensure all connectors within the detector head are attached.
• Ensure a voltage is present at the loop current connections at the detector head terminal
block.
Unless the detector head is mounted a significant distance from the MCU this voltage
should be approaching 20V (7V minimum).
• Where an I.S. Barrier is fitted, check that the barrier fuse is intact.
Fault
A Flammable Head is attached to channel 1 but the reading on the Detector Head display is
a high negative number (e.g. –60).
• Check that the pellistor supply is connected to the head.
The flammable heads require a separate supply to provide the pellistors with current in
excess of the 4-20mA available loop current.
• Check that the ‘pwr’ supply measures 3.5V – 4.5V at the detector head.
The voltage supply for the pellistors is regulated within the detector head at a factory pre-
set level (2.0V for VQ2 type pellistors). In order to provide a regulated supply at the
correct voltage the detector head ‘pwr’ connection must receive a minimum of 3.5V.
Fault
The detector head displays a valid reading; however the MCU does not appear to be
displaying the same, or any valid reading.
• Ensure that the channel has been enabled within the software.
• Ensure the channel setup is correct i.e. gas type, range
• Check that the jumper switch settings are correct. For all Status Scientific Detector Heads J6,
J7 & J11 need to be switched ON.
• Calibrate channel.
Fault
The MCU does not appear to communicate with channels five to eight.
• Ensure interconnecting cable is correctly attached between upper and lower platforms within
the control unit.
• Ensure relevant channels are enabled within the software.
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