TM 11-5805-424-15/NAVSHIPS 0967-220-9010/TO 31W2-2G-41
(b) Check the voltage between the output and
(2) Remove the -15 volts from diode CRa, and
ground.
The voltage indication should be
jumper CRa to ground.
(Refer to the
approximately 0 volt. If not, check for shorted
appropriate schematic diagram and PC card
diode CRa and resistor Ra or diode CRb.
layout for this point.) The ME26A/U should
indicate approximately 0 volt. If not, check for
(c) If the voltage indications in (b) above are
open diode CRa or shorted resistor Rb.
correct, check for open circuit elements.
(3) Reconnect the input side of diode CRa to a - 15-
6-7. Isolating Troubles in Amplifier Stages
volt source; remove diode CRb from the -15-
a. Inverting Amplifier (A, fig. 5-7).
volt source, and connect it to ground. The ME-
(1) Jumper the input side of resistor Ra, to ground,
26A/U should indicate approximately 0 volt. If
and monitor the collector voltage of transistor
not, check for open diode CRb.
Qa (ME-26A/U set to measure - 30 volts dc).
(2) The voltage at the collector of transistor Qa
operate essentially the same way with a positive input
should be approximately -6 volts. If not, check
applied to any input to enable the gate. Check the
for a shorted transistor, open resistor Pb, or
GOA- and GOB-type OR gates as described in (1)
open diode CRa (if used).
below-; check the GOa- and Gob-type OR gates as
(3) Remove the ground connection from resistor
described in (2) below.
Ra., and jumper the input side of resistor Ra to
(1) GOA- and GOB-type OR gates.
a -15-volt source. (Refer to the applicable
(a) Connect the input side of all input elements
schematic diagram and PC card layout for this
(illustrated by diodes CRa and CRb in A, fig. 5-
point.)
6) to a source of - 15 volts de. (Refer to the
(4) The voltage at the collector of transistor Qa should
applicable schematic diagram and PC card
be approximately 0 volt. If not, check for open
layout for this voltage point.)
resistor Ra, shorted resistor Rb or Rc, shorted
(b) Check the voltage across resistor Rc.
diode CRa or CRb (if used), or open transistor.
The voltage indication should be approximately
0 volt. If not, check for open resistor Rc or
shorted diode CRa or CRb.
the equipment, one employing a PNP transistor ((1)
below), and the other employing a NPN transistor with a
(c) Remove the - 15 volts from the input of CRa,
collector limiting resistor ((2) below).
and jumper the input to ground. The voltage
(1) PNP emitter follower.
across resistor Ra should indicate approximately
0 volt; if not, check for open diode CRa, open
(a) Jumper the base of transistor Qa, to ground,
resistor Ra, or shorted resistor Re.
and monitor the emitter voltage of transistor Qa
(ME-26A/U set to measure - 30 volts dc).
(d) Return the input side of diode CRa to - 15 volts,
and jumper the input side of diode CRb to
(b) The voltage at the emitter of transistor Qa
ground.
The voltage indication should be
should be approximately 0 volt. If not, check for
approximately 0 volt. If not, check for open
shorted transistor Qa.
diode CRb or0 open resistor Rb.
(c) Remove the ground connection from the base of
(2) GOC- and GOE-type OR gates.
the transistor, and jumper the base to a -15-volt
(a) Connect the input side of diodes CRa and CRb
source. (Refer to the applicable schematic
to a source of -15 volts dc.
Refer to the
diagram and PC card layout for this point.)
applicable schematic diagram and PC card
(d) The voltage at the emitter of the transistor
layout for this voltage point.
should be approximately -15
6-55
