Murphy Wiring the OS77 Series, Setting the OS77 Series, Warranty, Hook Up And Adjustments

HOOK UP AND ADJUSTMENTS

Wiring the OS77 Series

WARNING: BEFORE WIRING THE OS77 MAKE SURE THE POWER SOURCE IS OFF AND EQUIPMENT IS STOPPED.

OS77D Model Typical Wiring Diagram (Negative Ground Only)

OS77518PH/518APH

Key Switch

Setting the OS77 Series

The OS77 Series module must be fully installed and properly wired before attempting any of adjustment steps. These adjustment steps must be per- formed before the fine tuning can be accomplished and should be performed for first time setup of the OS77.

Note for relay output models only (OS77R): The following instructions assume terminal 5 is grounded. Relay contacts are between terminals 2& 5.

1 2 3 4	5
	***	R
		G NO NC SW1 SW2 B

*

Pickup**

+ –

Pressure Temp.

Hold	To Starter
coil

I

B S

To

Starter

–+

Battery

1.	Turn the “SPEED ADJ. ” potentiometer	Detail 1
	fully clockwise (Detail 1).
2. Remove the wire from terminal #2 of		OS77 Module
	the OS77 terminal block (Detail 2).
		Front View
3. Start engine and run at the highest
	RPM desired. This is the RPM at
	which the engine should be shut-	Lower	Raise
	down if exceeded.
		Speed Adj.
4.	Connect a Voltmeter or a test light
		Potentiometer
	between terminals #1 (positive+) and
	terminal #2 (negative) of the OS77 ter-

Ignition Coil Fuel Valve Rack Puller

OS77I Typical Wiring Diagram (Distributor Ignition Applications)

OS77 518PH/518APH

Key Switch

minal block. You should read no voltage
or the test lamp will be OFF.	Detail 2
5. Slowly turn the “SPEED ADJ. ”	OS77 Module
pot counter-clockwise and stop
the INSTANT the battery volt-	Back View

Pressure

Temp.

I

age is indicated on the meter

1 2	3 4	5
		R
		*** G NO NC SW1 SW2	B

*

+ –

To Distributor

Hold coil

B S

To

Starter

– +

Battery

To Starter

or the test light comes ON.
6. Slowly turn “SPEED ADJ.”
pot clockwise about 1/8 of an	1	2	3	4
inch. Now, tighten the locknut
(bigger nut) on the SPEED						To Battery–
ADJ. pot without disturbing
the setting.						To Pickup
7. Re-connect the wire to terminal					To Battery +
#2 on the OS77 terminal block.			Light

Ignition Coil Fuel Valve Rack Puller

OS77I Typical Wiring Diagram (For Shutting Down Magneto Ignitions)

OS77 169PH Magnetic Switch Ignition

	5
1 2 3 4	***
	B	S	C G
	Pickup**
			+	–
			Battery

* Applies to 518APH model. ** Always use shielded cable.

*** Applies to Relay output models only. B+ can be switched on Relay output models if desired.

This reconnects the SPEED	+		--
shutdown circuitry.
		Meter	OR

NOTE: If further adjustment (fine tuning) is needed: Turning the SPEED ADJ. pot clockwise, RAISES the shutdown point. This allows the engine to run at a HIGHER RPM. Turning the SPEED ADJ. counter-clockwise LOW- ERS the shutdown point. This will shutdown the engine at a LOWER RPM.

Warranty

A two year limited warranty on materials and workmanship is provided with this Murphy product. Details are available on request and are packed with each unit.

In order to consistently bring you the highest quality, full featured products, we reserve the right to change our specifications and designs at any time.

FRANK W. MURPHY MANUFACTURER P.O. Box 470248; Tulsa, Oklahoma 74147; USA tel. (918) 627-3550 fax (918) 664-6146 e-mailsales@fwmurphy.com http://www.fwmurphy.com

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