UVP UVX Radiometer - Manual (Page 11)

UVX Radiometer 11
Troubleshooting Procedures
In the event the Radiometer malfunctions, the following procedures will enable the user to determine the
source of error and affect repairs.
If any of the active circuit elements are replaced in the following procedures, then the calibration
procedure must be performed prior to putting the Radiometer back into service.
Troubleshooting Tips
The following paragraphs detail some of the more common malfunctions of the circuit and give the basic
procedures by which the cause of the circuit malfunction can be determined and ultimately corrected.
These procedures are limited to those active elements that can be easily removed and replaced.
Remove the circuit board from the case. Check the battery voltage to make sure it is still above 7.0 volts.
If it is, connect the battery back into the circuit. If it is not, replace it with a new battery.
Note: In the event any component is removed and replaced as a result of any work done on this unit,
then the full calibration procedure must be performed.
• Display segment does not turn on:
Turn the unit on and observe the display during the first second of operation: i.e. during test
mode. In this case the display should indicate “LOBAT” (for 2014 and newer models) and -18:8.8.
In the event any of the segments of the display is not on, it may indicate that a contact is not
making a firm connection at the liquid crystal display.
To correct this, use a pencil tip and place it on the pin contact of the malfunctioning segment.
(Refer to Figure 4 for the display pin-outs) Carefully work the contact pin back and forth with the
pencil tip and watch the segment. Performing this operation will generally correct all display
segment malfunctions.
• “LOBAT” (2014 and newer models) or colon (“:” on 2013 and older models) does not
appear on the display:
If “LOBAT” / “:” does not appear during the test mode, refer to the previous troubleshooting topic.
If “LOBAT” / “:” does not operate as a result of low battery voltage conditions and a new battery
has already been installed, then proceed as follows.
Disconnect the battery from the circuit and connect the circuit to a variable 0 to 10 volt DC power
supply. Set the power supply voltage at 9 volts. Turn the power supply and the unit on.
Slowly reduce the output of the DC power supply to 7.0 volts. If “LOBAT” / “:” does not appear,
then the trimpot RV2 is out of adjustment or the integrated circuit U2 is malfunctioning.
With the power supply set at 7.0 volts, adjust trimpot RV2 fully counterclockwise then fully
clockwise. If “LOBAT” / “:” does not come on at any time during this adjustment, then the
integrated circuit U2 is malfunctioning. Remove U2 and replace it with a new integrated circuit.
• Decimal point does not turn on:
Turn the unit on and place the range switch in the position in which the decimal point should be
on. Connect the negative input of the voltmeter to the negative side of the battery.
If the decimal point that should be on is the one corresponding to the 20 uW/cm
2
range, then
connect the positive side of the voltmeter to pin 9 of integrated circuit U2. If the decimal point that
is not on corresponds to the 200 uW/cm
2
range, connect the positive input of the voltmeter to pin
12 of integrated circuit U2.
When the range switch is in the appropriate position for the decimal point to be on, the voltmeter
should read the battery supply voltage; i.e., 9.0 volts. When the range switch is in some other