Macurco DVP-120 Installation & Operating Instructions Manual
Also see for DVP-120: User instructions
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Contents
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Revision 0.07 364 TroubleshootingThe DVP-120 is extensively tested at the factory to ensure reliable operation. Most problems can be traced tothe set-up of configurable features and modes, system wiring or trouble with the sensors.4.1 System Status Light FlashingThe system status light (section 3.1.1) is normally green indicating power is present, but will change to yellowwhenever the controlling firmware detects a trouble condition. Possible trouble conditions are– Any configured channel has less than 4 mA flowing in the current loop– A sensor is reporting a trouble condition– Any configured channel wiring is open.– Internal controller board problems are detected.4.1.1 Input Channel TroubleAny time the POWER light is yellow, the first thing the technician should consider is that one of the inputchannels is in trouble. Reviewing the Sensor Status displays (using the up and down keys), should reveal whichchannel has a problem since the gas reading will be replaced with the word TROUBLE.A common source of trouble is an input channel that is configured for a sensor that does not exist. In this case,the system expects to see current flowing within the current loop, but there cannot be current if there is nosensor connected. Either fix the miss-wired sensor, or change the sensor type to NONE, section 3.3.3.2. Afterreturning to normal mode (using the MENU key), the power light should return to steady green.If all channels are configured properly, another source of trouble could be the type of sensor attached to an inputchannel. Macurco Toxic sensors can indicated high gas concentrations with signals of up to 24 mA in thecurrent loop. However, the combustible sensor (GT-11A) can indicate trouble with a 21 mA signal. Therefore, aToxic sensor connected to channel which is configured for a combustible sensor can cause a fault indication ifthe gas concentration is high enough.All Macurco sensors are either supplied with a STATUS lamp that will indicate the health of the device, or willdisplay a trouble message on the digital display. Macurco sensors may be tested by depressing the TEST buttonon the sensor printed circuit board, or (depending on the type of sensor), the button on the interior front panel ofthe unit. Macurco sensors will step the output current level from 4 mA to 20 mA over the course of the warm-upperiod, allowing the technician to determine where the trouble exists. If the sensor is still in trouble, resettingthe power may clear the trouble. Remove one of the power wires from the sensor terminal strip causing thesensor to go through a power-up reboot.Finally, the wiring between the DVP-120 and the sensor should be investigated. The power input to the sensorshould be investigated at the sensor. Since Macurco sensors are rated for operation between 12 and 24 VDC orVAC, the voltage drop between the DVP-120 and the sensor should not be an issue if the wiring guidelines inTable 2-2 are followed. A multimeter can be inserted to check the current flow within the loop, or a continuitytest can be performed on all four wires between the DVP-120 and the sensor. Ensure power is removed from theDVP-120 prior to removing the input or output connectors from the DVP-120 controller board.Each sensor channel is provided with a PTC-resettable fuse internal to the DVP-120 to protect against overcurrent situations. To reset a sensor channel, power should be removed from the channel. This can beaccomplished by removing power from the sensor – causing the loop current to go to zero, or by completelyremoving power from the DVP-120.4.1.2 Internal Controller Board TroubleIf the sensor status display and investigative efforts reveal no problems with the input channel current loops andchannel configuration, the most likely trouble is an internal problem detected by the DVP-120 controller. In thiscase, contact the Macurco Technical Department for advice and help.4.2 Timed ventilation problemWhen using the timed ventilation mode the system clock should be checked regularly (at least twice a year).The battery backed real time clock in the DVP-120 does not adjust for daylight saving time so the spring andfall switch over points are good choices to check the system clock. |
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