Service manual

STP 11-25R13-SM-TG
B - 2
(3) Diodes. All diodes can be checked for an open or shorted condition by measuring the
resistance between the terminals. Use an ohmmeter set to the 1k scale to keep from damaging the diode
for measuring the diode resistance. The resistance should be very high in one direction and very low
when the ohmmeter leads are reversed.
(4) Resistors. Resistors can be checked with an ohmmeter. Check the replaceable electrical parts
list for the tolerance of the resistors used in the instrument. Resistors normally do not need to be
replaced unless the measured value varies widely from the specified value.
(5) Inductors and Switch Contacts. Check for an open circuit (that should normally be closed) by
checking conditions with an ohmmeter.
(6) Capacitors. A leaky or shorted capacitor can best be detected by checking resistance with an
ohmmeter on the highest scale. Do not exceed the voltage rating of the capacitor. An open capacitor
can best be detected with a capacitance meter or by checking whether or not the capacitor passes AC
signals.
WARNING
Because of component density on circuit boards, care should be
taken with the meter leads and probe tips. Accidental shorts can
cause abnormal voltages or transients that may destroy
components. Ground lugs are not always at ground potential.
Check the diagrams before using such connections as ground for
meter leads or oscilloscope probes. Some transistor cases may
be elevated.