Table 3-6. Troubleshooting
Chart-Continued
TM 11-6125-261-30
Corrective
Correct
Test
Possible
Cheeks
Malfunction
action
reading
cause
conditions
3 pulser switches is
shorted collector to
emitter. Replace all
three. A failure of this
type may take out all
five transistors in a
Check for 115 V ac at pins as noted
7. Fan does not Vin 26-29 V ac. All Defective fan.
pulser section. Check the
1 and 2 of fan and a phase
outputs normal. Any
operate.
other two transistors
load condition.
shifted voltage at pin 3.
carefully. Replace as
Note
required.
Fan may slow down
Replace fans if voltages are
under some load
correct. Replace C35 if pin
conditions but air
3 voltage not present or if
must continue to
waveform is in the same
flow at all times.
phase as pin 2.
Proceed to Section IV,
Open padding
Any normal
8. Frequency not
Maintenance and adjust the
operating condition. capacitor.
4 0 0 7 Hz.
frequency in accordance
See Table 1-1.
with para 3-7.
Refer to malfunctions 2,4
9. Unit does not meet
and 5 of this table. If these
distortion
did not correct the problem,
specifications.
replace the main
transformer A3T1, para 3-
10. Unit has low
11E. Refer to malfunctions
efficiency.
2,4 and 5 of this table.
Check that output
ammeters are calibrated for
400 Hz. Clamp-on type
ammeters should be
avoided as they are
generally accurate for 60 Hz
only.
With Vin at 26 V dc and Vout should be 65 V ac 5
Refer to Section IV
Overload
11. Overload input Vin + V dc Load
Maintenance, paragraph
each phase at 4.36 amps V ac.
current exceeds equals 4.36 amps per misadjusted.
3.
load.
specification but phase or greater.
doesn't limit.
Check A22CR112, Q112,
Refer to Chapter 2. Check 2. Signal A2 goes more
Vout should begin to Broken wire,
12. No limits on
and CR108 (6A). Replace
negative with higher loads.
voltages of divider
overload. Usually decrease when lout defective diode,
as required.
exceeds 3 amps per defective transistor. carefully.
on one phase
phase.
only.
Refer to Section IV
13. Short circuit
Maintenance, paragraph
output current
3-9.
less than 5.45
amps per phase.
Refer to Section IV
14. Short circuit
Maintenance,
output current
paragraph 3-9.
less than 5.45
amps per phase.
Use a VOM to check
As noted.
Refer to Chapter 2.
15. Unit does not Vin + 27 V dc 1 V U29 defective
transistors A22Q113, Q114
fold back in moredc. Output shorted
A220113, 0114,
and Q115. Replace if
115 defective.
than 5 sec. or less all 3 phases.
defective. U29 should show
than 20 sec.
about 35 ohms from pin 4
to any other pin. This diode
is in series with a small
inductor. Replace if any pin
shows a high resistance.
A22R129 is nominally 68K.Refer to Section IV
A22R129 value too
16.. Unit does not
Maintenance paragraph
high.
recover quickly
3-9.
after short circuit
3-19
or overload test.
