Melink Intelli-Hood Controls Reference Manual page 20

Operation/Service Specifications for Melink Intelli-Hood Operator
Advanced Troubleshooting
This section will deal with phenomena that are not mentioned in the standard troubleshooting guide. The
following actions take a more subjective approach to the problems.
General Procedure For Isolating Bad Components
Temperature Sensors
•
Verify correct number of sensors are programmed for the hood and that all plug-n-play
connections are secure.
•
Ensure no "Y" cables are plugged in at the IOP. Plugging temperature "Y" cables in at the IOP
can cause erratic behavior due to the wiring used internally. Always plug these in at the sensor.
•
Check resistance between Pin 1 and Pin 2 at the end of the cable plugged into the IOP.
Resistance value should be approximately 109Ω per sensor. If there is more than one sensor,
multiply 109Ω by the number of temperature sensors for that hood to get an approximate value.
If resistance is incorrect, check temperature probe and cable individually to determine
o
problem component and replace as necessary.
If issue is low resistance (i.e. approximately half to a third of expected value) and a "Y" is
o
being used, verify that a temperature "Y" is in place and not an APU "Y". The APU "Y"
will put the resistances in parallel, effectively reducing it to the point that the system will
never operate at more than minimum speed on temperature.
•
If temperature faults are still present after these checks, it is possible that the problem is coming
from the optic circuit (this has been known to happen in the past). To check for this condition,
eliminate any optics on non-calibrated channels in the Simplissimo programming as well as
disconnecting the cables from the IOP. If the system now runs fine, the culprit is probably in the
optics portion. If the system does not work, it is possibly a bad Autocal board that may need to
be replaced.
Optic Sensors
•
Verify that the correct optic channels are programmed for the given system.
•
Check optics alignment in Simplissimo System Menu #9.
If a strong signal is present (4-8 bars), verify that breaking the beam reduces the signal to
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one bar.
If a weak signal (2-3 bars) or no signal (1 bar) is present, increase the gain setting on the
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receiver.
•
If system is running at full speed for no apparent reason, try re-calibrating the optics (turning
system on and off). Also try programming out the optics and re-testing the system.
If the system runs normally in temperature only, but at full speed with the optics then
o
check the voltage output from the receiver. There should be 1-2 volts (DC) between the
ground post on the Autocal board and the respective receiver points on the Autocal. The
test points are labeled RCV0 through RCV3 for channels 1 through 4 respectively. If the
voltage is below one volt with the gain setting at the appropriate level, the optic boards
will need to be replaced.
•
If possible, switch optic boards from malfunctioning channel with boards from a working optic
channel. If the problem jumps with the optic boards, then the problem is with either the emitter or
receiver. If the problem does not move, then the optic boards are fine and more checks need to
be made:
If possible, try to isolate if the problem is in the cables by switching the optics "Y" (with all
o
existing cables attached) with a working channel. If the problem moves at this point, then
the problem can most likely be attributed to a bad cable. If the problem does not move at
this point then the Autocal board is probably malfunctioning and should be replaced.
Check cables: Use a "pigtail plug" (female plug with wires that can be twisted together for
o
a continuity check) to short two pins together and check for continuity at the other end of
the cable. Also check for shorts to other pins. The optic channel uses pins 1, 2, and 3 on
the 4-pin cables. Replace any bad cables and retest system.
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