TM 5-4520-240-14
CHAPTER 8
REPAIR OF IGNITION POWER SUPPLY
8-2. Removal.
8-1. Description.
WARNING
a. The ignition power supply (12, fig. 4-7) is mounted
T h e ignition system of this space
in the bottom of the heater housing, It converts 28 vdc
heater contains dangerous voltages
input to the high voltage output necessary to provide a
w h i c h can cause severe electrical
hot spark at the igniter in the burner head. This spark
shock. Be sure to disconnect the power
is necessary to ignite fuel vapors to start combustion. A
plug before repairing the heater.
shielded high voltage cable connects the secondary of
a. Disconnect the power plug and remove the top and
the power supply to the igniter,
side panels to provide access to the ignition power sup-
b. The ignition power supply employs two transistors
ply.
which provide a pulsating current in the primary coil to
b. Disconnect the ignition cable from the igniter,
induce a continuous voltage step-up in the secondary
c. Disconnect the yellow primary lead from the tab
coil. The coils are potted in the transformer box and are
on the terminal block.
not replaceable. All components of the power supply
d. Remove the two nuts (1, fig. 8-1) and lock washers
are mounted in the box except the transistors. The
(2) that secure the ignition power supply case (18) to the
transistors are mounted on the box cover to provide bet-
studs on the bottom of the heater housing, remove the
ignition power supply and lock washers (3).
ter heat dissipation.
8-1
