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EDM RPM to the mag ‘P’ leads?

 NO! — this is a high voltage area. The magnetos should have a vent plug for the RPM sensor to be attached. The Slick 600 Press- Series does not have vent plugs, and can use the #420806 ‘Modified’ sensor. If the your magneto is an older type that does NOT have any vents, then this type of sensor may work too

How to hook up EDM-700-7C/9C to tach generator?


For a Waco Classic Aircraft – Cessna 195 7 cylinder Jacobs R755B -uses the TSO’d UMA Tach sender. (p/n T1A3-4 TSU;  TSO# -TSO-C49b) Program the RPM RF in the EDM under ‘FAC LIM’ to ‘CYL= ‘8’. (2 pulses per revolution.) T1A3-4 TSU specifications are: power:  5-16vdc 10mA

For 9 cylinder War Birds such as the T-6 and T-28B’s, and Rotax and SMA engines (SMA- SR 305-230 piston engine, with a diesel cycle technology, burns jet fuel) — DO NOT USE BENDIX/SLICK MAG PICKUPS, OR UMA CONNECTORS. — They use the “AC-to-Pulse Converter“. One end of this converter has the white Molex connector that plugs into the EDM RPM harness – (red/black/green wires) In line with the converter wire is a circuit board shrink wrapped. On the other end of this converter, which connects to the tach generator or Tach gage, there are only two(2) wires – white(signal) and black(grnd). These can be hooked to the back of the aircrafts Tach gage. Again ‘black’ grnd to ground and the ‘white’ to either Signal A or Signal B – does not make any difference – choose either A or B.  If his tach generator has only two pins, then these are either signal A or B. The ‘case’ of this type of generator is the ground. Program the RPM RF in the EDM under ‘FAC LIM’ to ‘CYL= ‘4’ or ‘8’ (2 pulses per revolution.)

RPM sensors?

BENDIX series -20, -21, -200 (S4LN-XXX, S4RN-XXX, S6LN-XXX, S6RN-XXX):
-Non-pressurized -#420815-2
-‘Pressurize’ is # 420806.

Bendix 1200:
– Non-pressurized – # 420815-2
-‘Pressurize’ is # 420807.

Bendix dual mag – D-2000 or D-3000 – No # -just specify “Bendix Dual”

SLICK 4000 or 6000:
-Non-pressurized – #420815-1
-‘Pressurize’ is # 420809.

Slick 600 Pressurize is # 420806.

*** Pressurized mags have a ‘Pressure Tube Fitting’ on the magneto.

How do I adjust MAP constant?(New software Rev.)


The EDM and MP sensor are already calibrated. So in PROGRAM mode he will see only a + to – 3. He will use the LF button to ‘tweak’ this value.You should be on the ground with the engine off to perform this procedure…

1. Go to pilot program mode (Hold both buttons to see PROGRAM).
2.Tap STEP until you see HP-?Y.
3. Hold both buttons until the display changes.
4. Hold both buttons until the display says MAP – +/- 3    He will use the LF button to ‘tweak’ this value. Tap ‘Step’ to accept the change.

RPM, wrong reading or erratic

• Could be a ground issue. The instrument to engine ground was may be fouled. Cleaned it and recheck operation.

• Check that the wiring is not adjacent to ignition wires.

• Check that CYL in FAC LIM of the EDM is set correctly to 4 or 6 or 8 for Bendix dual D2000/3000 magnetos or 12 for a Unison Laser ignition.

• Check location of sensor. Make sure sensor is mounted as illustrated in installation manual.

• Check with a degausser (available at Radio Shack): 4 cyl should read 3600 rpm and 6 cyl should read 2400 rpm; 8 cyl 1800; 9 cyl 1600; 4 cyl dual mag 1800; 6 cyl dual mag 2400.

• Make sure the correct sensor is being used. For BENDIX series -20, -21, -200 Non-pressurized -#420815-2 — Pressurize is # 420806.    For Bendix 1200 Non-pressurized -# 420815-2 —– Pressurize is # 420807. For the Bendix dual mag – D2000 or D3000 – No # -just specify “Bendix  Dual”     ——-         For  SLICK 4000 or 6000 -Non-pressurized – #420815-1 — Pressurize is # 420809.  For the Slick 600 Pressurize is # 420806.

•With oscilloscope or Frequency Counter-( If they do not have these, ask if their digital voltmeter has the ‘Hz’ option on the dial. They can use that if it does. Meter’s red probe to the green wire on RPM sensor and the meter’s black probe to black ground wire on RPM harness. Do not use engine ground.) —- They should see these values per RPM / HZ:  500 RPM=12.50HZ; 1200 RPM=30.00HZ; 1550 RPM=38.75HZ; 1900 RPM=47.50HZ; 2250 RPM=56.25HZ; 2600 RPM=65.00HZ; 3500 RPM=87.50HZ

Will JPI products work with Light Speed Ignition?

Yes. Light Speed #1 and Light Speed #2:

Will need schematic on Lightspeed Tach Pulse ‘Out’ and Tach Pulse Ground  to EDM RPM harness signal(green) and ground(blk) wires. Call Technical Support.

Program the EDM in ‘FAC LIM’ to:   Cyl = 4 > RF = 8 ; Cyl = 6 > RF = 12

Will JPI products work with LASAR Ignition (Unison/Slick)?

Uses Slick sensor. Two(2) pulses per rev. For the EDM in ‘FAC LIM’ , program “CYL=XX” field to different RF value:  4 cylinder set to 8 cylinder. 6 cylinder is a special (as if set to 12 cylinder).

Is my factory RPM sensor compatible

IO-550 engines made after 2002 may have a compatible RPM sensor installed (+5v active sensor), but the JPI unit should be used.

No RPM reading – shows only zero(0).

• Check connections to sensor.

• Make sure you have the RPM sensor on the correct vent plug of the magneto. You should see the rotating magnet in this hole. If you see a ‘gear’ you’re on the wrong vent.

• Check with a tape recorder head degausser (available at Radio Shack):
4 cyl should read 3600 rpm
6 cyl should read 2400 rpm
8 cyl 1800
9 cyl 1600

 4 cyl dual mag 1800
6 cyl dual mag 2400.

• The RPM sensor red wire should have 5v. The green wire is signal and will have a 0-5v square wave.

 ** Or if his digital voltmeter has HZ (hertz) ability – connected to the sensors green signal wire and sensor ground (blk):
1200 engine RPM= 30.00 Hz
1550 engine RPM= 38.75 Hz
2250 engine RPM= 56.25 Hz.

What is the thread for the Manifold Pressure sensor?

The MAP sensor uses a 1/8 NPT fitting. MP sensor p/n 604010

How do I adjust MAP constant?(Older software Rev.)

You should be on the ground with the engine off to perform this procedure.

  1. Go to pilot program mode (Hold both buttons to see PROGRAM).
  2. Tap STEP until you see HP-? Y.
  3. Hold both buttons until the display changes.
  4. Hold both buttons until the display says MAP – 29.9.
  5. Tap or Hold the LF button to set the display to match the field MAP setting (NOTE the current altimeter setting, unless you are at sea level; see Pilots Guide for table)
  6. Tap STEP and see CYL = 4 or 6 or 8 for dual (all in one) magnetos or 12 for a Laser ignition.
  7. Hold both buttons to exit.

Manifold Pressure not reading correctly?

#1) Make sure connector plugged into the MP sensor has not come loose or is plugged in upside down. Also make sure the small ‘hole’ in the screw in side of the sensor is not plugged up.

#2) Make sure the pins inside MP sensor are not bent.

#3) Check voltages on MP sensor wires with MP sensor plugged into EDM and power on. Voltage between:

Red & Blk = 5V
Blk & White = 2.5V
Blk & Green = 2.5V
White & Green = 10.16mV (milli volts) if pressure is around 30.0 HG.

**[[ Other milli volt readings you should see between White and Green wires at different pressures: 3.386mV at 10.0 HG; 5.080mV at 15.0 HG; 6.773mV at 20.0 HG; 8.466mV at 25.0 HG; 11.85mV at 35.0 HG; 13.55mV at 40.0 HG, and 15.25mV at 42.0 HG]]

** HG stands for Inches in mercury.**

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