Troubleshooting
Apollo SL40 Field Maintenance Manual
5
S
ECTION
2 - T
ROUBLESHOOTING
This section provides information to assist in isolating problems with the SL40. Where
required, detailed drawings of test setups are provided. The specified test equipment is a
recommendation based on the equipment used to test the SL40 during manufacture and
factory service. Alternate, but equivalent, equipment may be substituted if the recommended
equipment is not available.
O
VERVIEW
Field maintenance of the SL40 is limited to replacement of the SP96 Com Display Board
and the VHF Com Main board.
ESD S
AFE
W
ORK
A
REA
R
EQUIREMENTS
The SL40 circuit boards contain electrostatic discharge sensitive (ESDS) components. To
prevent damage to the ESDS components, the circuit boards must be removed from the
SL40 and handled in an ESD safe work area only. The work area must comply with the
requirements of IPC 610A or other equivalent document. At a minimum, observe the
following the following precautions when handling SL40 components.
Both you and the work surface must be properly grounded before handling the SL40
components. If moving the SL40 components from one area to another, they must either
be reinstalled in the SL40 case or placed in an anti-static bag.
P
RELIMINARY
C
HECKOUT
Perform the following tests before removing the SL40 from the aircraft to determine if
the problem is in the SL40 or the aircraft.
Transmission and reception range is normally not a problem in aircraft due to the aircraft
height above terrain. Poor reception range that can be traced to aircraft noise or antenna
performance is usually repairable.
The SL40 has a number of “System Functions” to assist in isolating Comm problems.
Two of these features assist the operator or service personnel, in evaluating the aircraft
communication environment: Signal Strength Display
(RFLVL)
and Audio Noise Level
Display (
NOISE
). Additionally, there are several adjustments, which if improperly set,
can give the appearance of a malfunctioning radio. If the system functions fail to pinpoint
or correct a Comm problem remove the SL40 from the aircraft and refer to the Equipment
Test procedures on Page 12 for bench testing. A built in Display test function allows
isolation of Com Display board malfunctions with the SL40 mounted in the aircraft. If a
problem is isolated to the SL40 (Com Display board or Com Main board) refer to the
Disassembly procedures on Page 20 for instructions on removing and replacing the
malfunctioning component.
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