Chapter 10 Troubleshooting
10-10
Condition Cause Corrective Action
The load does
not turn off.
y Sneak current due to the use of two
different power supplies.
E1<E2, sneaks. E1 is off (E2 is on), sneaks.
y Use only one power supply.
y Connect a sneak current prevention
diode.
If the load is the relay, etc, connect a
counter-electromotive voltage absorbing
code as shown by the dot line.
The load off
response time
is long.
y Over current at off state [The large
solenoid current fluidic load (L/R is large)
such as is directly driven with the transistor
output.
y The off response time can be delayed by
one or more second as some loads make
the current flow across the diode at the off
time of the transistor output.
y Insert a small L/R magnetic contact and
drive the load using the same contact.
Output
transistor is
destroyed.
Surge current of the white lamp
A surge current of 10 times or more when
turned on.
y To suppress the surge current, make the
dark current of 1/3 to 1/5 rated current flow.
Sink type transistor output
Outpu
Loa
Output
E
R
Output
E1
Output
Load
E
E
E1
Load
E2
Output
Outpu
Loa
E
Off current
Output
E
R
Source type transistor output
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