TM11-6125-256-34
a Replace the voltage and frequency regulator as-
a Shut off dc input power
sembly as described in paragraph 3-14b
b Repeat the procedures of paragraph 4-10 2 If
sembly from the motor-generator as described in para-
the measurements of paragraph 4-10 2, steps d(1)
graph 3-14a
through d(3), are satisfactorily made, the assembly has
c Check the suspected component(s) Section VI
been repaired satisfactorily
gives the electrical component test values for the volt-
c Turn off dc input power
age and frequency regulator assembly components
d Remove the voltage and frequency regulator as-
d Check to see that replacement parts are available
sembly from the motor-generator as described in para-
To replace the faulty parts, proceed as follows
graph 3-14a
(1) Using a 23- to 37 5-watt pencil-type solder-
NOTE
ing iron, heat and peel off the polyurethane coating
Do not remove voltage adjust resistor (R23)
from the component to be replaced
from control box assembly Remove hard-
(2) Using the soldering iron and a vacuum solder
ware and disconnect leads from terminals 8,
removing tool, remove solder from the component leads
9, and 11
and remove the component leads Where necessary, use
e With the exception of transistors Q6 and Q11,
an appropriate heat sink to prevent damage to adja-
associated heatsinks and hardware, terminal clinch-nut
cent components
threads, the areas within 1/4 inch diameter of the
clinch-nuts on the copperside, and within 7/16 inch
CAUTION
diameter of the mounting holes on both sides of the
Do not clean printed wiring board assembly
board, spray the voltage and frequency regulator as-
(43, fig 4-5 1) unless absolutely necessary
sembly with Hysol PC 28 STD urethane coating (Hysol
as cleaning solvents may damage coating
Division of the Dexter Corporation, Olean, NY) as
follows
(3) Using the old component as a guide, form
and cut the replacement component leads, as required
WARNING
After positioning the component or leads in place,
Contents of spray can are under pressure and
solder securely as follows
flammable Do not spray near fire, flame, or
heated surfaces Do not store can at a tem-
NOTE
perature above 120F (48 8C) Avoid
breathing of vapors, prolonged contact with
Equivalent soldering materials may be used
the skin, contact with open breaks in the skin,
and ingestion Wash hands thoroughly after
(a) Use the 23- to 37 5-watt soldering iron Be
handling and before eating and smoking
sure the tip is clean, free from oxides, and coated with
a film of solder
(1) Shake spray can a few times to completely
mix material in spray can
eter core) and Kester No 1544 liquid flux (Kester
(2) While spraying, hold spray can approximately
Solder Company, Newark, New Jersey) The solder
6 inches from area to be sprayed
consists of 63 percent tin and 37 percent lead and has
(3) Allow coating to cure for a minimum of 4
a melting temperature of 357F (181 C)
hours at room temperature before handling sprayed
(c) Clean the joints with Lonco flux remover
surfaces Allow 24 hours at room temperature for com-
(London Chemical Co, Melrose Park, Illinois)
plete curing
