4230 Flow Meter
Section 5 Maintenance and Service
5-14
5.8 Preliminary
Troubleshooting Steps
CAUTION
Do not attempt to disassemble or repair the 4230 Flow Meter
(other than changing fuses) unless you are skilled in the evalu-
ation and repair of microprocessor-based circuitry. Isco recom-
mends no attempt be made to disassemble or repair the
printer mechanism or display module.
The electronic circuitry of the 4230 is solid-state and its reli-
ability is high. If the unit should fail to operate properly, the
problem is most likely a mechanical failure. Items such as a
broken or intermittent connection in the power cable or wiring
harness or (rarely) poor electrical connection through keypad
switches should be suspected.
5.8.1 If Serious Problems
Occur
If you suspect an electronic problem, Isco strongly recommends
that you call the Isco Technical Repair Department. (800)
775-2965 or (402) 464-0231 outside the U.S.A. The service
department will advise you on how to return the 4230 to the
factory for servicing.
The Technical Repair Department has trained technicians and
specially-designed equipment necessary for timely, efficient
repair of the 4230 Flow Meter. If you still wish to attempt
repairs, the Technical Repair Department is available to provide
additional advice and information on servicing.
5.8.2 Processor When attempting to isolate problems within the unit, you should
assume that the CPU and memory are working properly until
attempts to find problems in the peripheral circuitry have been
exhausted.
This is for two reasons: First, the likelihood of failure is far
greater on transistor drive circuits (heavier currents are handled
here), than on the CPU or memory. Second, it is doubtful that the
repair facility would have the time or equipment to do worth-
while troubleshooting (beyond exchanging components) on the
CPU or memory.
When the unit does not work, do not automatically assume the
CPU is at fault. Following are suggested areas to check before
attempting to service the CPU and associated circuitry. Tele-
phone consultation with Isco Technical Service is strongly recom-
mended. Look for the following:
1. First verify that the problem is in the flow meter and not
caused by the bubble line, power supply, or any other
equipment connected to the flow meter.
The flow meter could be all right and will appear not to
work because of a clogged or leaking tube or other compo-
nent; check these first.
2. Check to see if any fuses are blown
3. Check the battery or power supply.
Proper voltage to the unit should be from 10.5 to 14.5 VDC.
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