Maintenance-7M13
Check
Associated Equipment
Before
troubleshooting 1he 7M13 Readout Unit, check 1hat the equipment used wi1h 1his instrument is
operating correctly. If possible, substitute another unit known to be operating co"ectly into
the
mainframe
and
see
if
1he problem persists. Check 1hat the input is properly connected and 1hat 1he interconnecting
leads
are not defective.
Visual Check. Visually check the portion of the instrument in which 1he trouble is suspected. Many
troubles can
be
located by visual indications, such as unsoldered connections, broken wires, damaged circuit
boards, damaged components, etc.
Individual Components. The following methods are provided for checking the individual components in
the 7M13. Components that are soldered in place are best checked by disconnecting one end to isolate the
measurement from the effects of related circuitry. Fig.
3-1
shows the lead configuration of
the
semiconductor devices used in this instrument.
1. TRANSISTORS
AND INTEGRATED CIRCUITS.
The best
check
of transistor and integrated circuit
operation is actual performance under operating conditions.
If
a transistor
or
integrated circuit is suspected
of being defective,
it
can
best
be
checked by substituting a component known to
be
good. However,
be
sure
that circuit conditions are not such that
a
replacement might also be damaged. If substitute transistors are
not available, use a dynamic tester,
such
as Tektronix Type 576. Static·type testers may
be
used, but since
they do not check operation under simulated operating conditions, some defects may
go
unnoticed. Fig.
3-1
shows
base
pin arrangements of semiconductor devices. Be sure the power is off before attempting to
remove or replace any transistor or integrated circuit.
Integrated circuits can be checked witt. a voltmeter, test oscilloscope, or by direct substitution. A good
understanding
of
the circuit description is essential to troubleshooting circuits using integrated circuits.
Use
care
when checking voltages and
waveforms
around the integrated circuits so that adjacent leads are not
shorted together. An integrated-<ircuit test clip provides a convenient means of clipping a test probe to the
14· and 16-pin integrated circuits. This device also doubles as an integrated-circuit extraction 'tool.
C
E
B
Index
C
E
B
Fig. 3-1. Semiconductor LeM! Configuration.
3·2
C
E
B
