Avionics Bending: N2 Tachometer - Pinout

The N2 %RPM indicator on the L-1011 is not located on the center panel, but on the flight engineers' engine status panel.

Unlike the tachometers on the pilots center panel, the N2 for the flight engineers does not have a digital readout ... it only has a pointer. However, the basic instrument principle of it being driven by a phonic wheel attached to the N2 compressor stage still applies. Below is the schematic for a General Electric %RPM N2 Indicator:

Here is the pinout:

Connector	Pin	Function
Sort	Sort	Sort

J1	01	5VAC/5VDC Instrument Lighting (Hi)
J1	02	5VAC/VDC Instrument Lighting (Lo)
J1	03	Tachometer Signal Twister Pair Shielding Ground
J1	04	Frequency Limit Elect - Ground
J1	05	115V 400Hz Power Supply (Hi)
J1	06	Tachometer Input TP - B
J1	07	Tachometer Input TP - A
J1	08	Casing Ground
J1	10	Over Limit Switch (Input)
J1	11	Over Limit Switch - Ground
J1	12	Frequency Limit Elect - Input
J1	13	AIDS Buffer Output
J1	14	115V 400Hz Power Supply (Lo)
J1	15	Frequency Limit Elect - Ground