4210 Flow Meter
Section 5 Maintenance and Service
5-12
instrumentation are required for troubleshooting. The Isco
service department has trained technicians and spe-
cially-designed equipment necessary for timely, efficient repair of
the 4210 Flow Meter. If you still wish to attempt repairs, the Isco
Customer Service Department is available to provide additional
advice and information on servicing.
5.4.5 Processor Servicing When attempting to isolate problems within the unit, the CPU
and memory should be assumed to be 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 unlikely
that the repair facility will have the time or equipment to do
worthwhile troubleshooting (beyond exchanging components) on
the CPU or memory.
5.4.6 Preliminary
Troubleshooting Steps
The electronic circuitry of the 4210 is solid-state and highly
reliable. If the unit should fail to operate properly, the problem is
most likely a mechanical failure. Items such as a broken or inter-
mittent connection in the power cable or wiring harness should
be suspected. When the unit does not work, do not automatically
assume the CPU is at fault. Telephone consultation with Tech-
nical Service is strongly recommended. Following are suggested
areas to check before attempting to service the CPU and asso-
ciated circuitry.
1. Check the ultrasonic transducer and its cable.
The flow meter could be all right and will appear not to
work because of a damaged cable or misaligned trans-
ducer; check these first.
2. Check to see if any fuses are blown.
Figure 5-7 Location of the Three Fuses
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