J.P. Instruments EDM 930 Primary Primary Installation Manual - Manual (Page 12)

FAA Approved Installation Manual for the Report No 908
EDM-900 and EDM-930 Page 12 of 50 Rev J
Primary Engine Data Management System Date 5-24-14
11. Power Connection
The EDM automatically adapts to either a 14 or 28-volt electrical system. Master Bus power wire to the EDM
should be 20ga copper connected directly to the master solenoid located at the battery to avoid a line drop when
cranking. A 5 amp circuit breaker is required. Connect the EDM ground wire to the engine block. The
instrument is designed to reset at less than 10vdc bus power, therefore the instrument may reset on engine start
(typical for 14vdc systems). For lighting, no connection to the aircraft dimmer system is required because the
instrument dims automatically with reductions in ambient light. Required power for 900 or 930 is 1.0 amp at 14vdc
12. Probe Wiring
When cutting the pair of leads to the proper length to connect to the probes, leave enough slack in the wiring so
that probe may be interchanged to an adjacent cylinder if necessary for trouble-shooting and servicing.
Thermocouple wire length is not critical and should be trimmed to any length as required for a clean installation.
The Temperature probe must be wired with the correct polarity. The temperature probe connects to its temperature
indicator with yellow jacket Teflon Chromel Alumel wire supplied. Strip the wires as shown below—observing color-
coding.
1/4" 1 1/2"
Fold back wire
double before
crimping terminals
2 1/4"
Thermocouple wire harness
red
yellow
Terminate each wire with a crimp-on ring terminal, provided. The ring terminals may be crimped with an AMP part
number 48518 crimp tool is recommended however, a “service-type” tool may also be used. Verify the quality of
each crimp with a sharp tug on the wire. The terminal should be impossible to pull off when crimped correctly.
shrink tubing
ring terminal
Place a ¼ x 4-inch sleeve over each pair of wires in the wiring. Connect the wire ring lug to the probe ring lug using
the supplied number 4 screws and nuts, placing the star washer between the ring lugs, not against the nut.
Important: place star waster between two ring
terminals and tighten nut and bolt as
necessary
to instrument
to probe
Slide the sleeve over the joint and secure with three tie-wraps.
1/4 x 4" sleeve
tie-wrap 3 places
The most common installation problems are related to poor quality terminations.
12.1 Wiring Markings
The EDM-900/930 is supplied with special Teflon insulated Chromel Alumel factory assembled wiring harness
configured for the correct number of cylinders. The wire harness is marked E1= EGT-1, C1= CHT-1, etc.
NOTE: Unlike most other EGT & CHT installations the probe wire length is not critical and should be
trimmed to any length as required for a clean installation. Do not extend the thermocouple wire with
copper wire.