9U6958 Magneto Peak Detect Module{1552, 0712, 0781} Caterpillar


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9U6958 Magneto Peak Detect Module{1552, 0712, 0781} [NEHS0588]
ELECTRICAL AND STARTING SYSTEM
MAGNETO GP
9U6958 Magneto Peak Detect Module{1552, 0712, 0781}
1.1. Introduction
2.1. Specifications
3.1. Description
4.1. Care and Cleaning
5.1. Operating Instructions
6.1. Troubleshooting
7.1. Service

Introduction

The 9U6958 Magneto Peak Detect Module provides the serviceman with an easy way to check the approximate spark plug firing voltage being supplied by the Altronics magneto on the 3500 series and some 3600 series spark ignited engines. The 9U6958 requires the use of the serviceman's voltmeter. An optional output is available that provides an output to an oscilloscope so that the waveform may be observed.


9U6958 Magneto Peak Detect Module 9U6959 T Cable

Specifications

Input 0 - 200 VDC
DC Voltmeter Connections 0 - 200 VDC
Scope Connections 0 - 200 VDC
Operating Temperature -40° F to 140° F (-40° C to 60° C)
Storage Temperature -40° F to 140° F (-40° C to 60° C)
Dimensions 7.5" x 6.6" x 1.6" (190 x 168 x 41mm)
Weight 1 lb. (0.5kg)

Description

INPUT

Input connector that connects the 9U6958 to the magneto under test using the 9U6959 T Cable.

SCOPE CONNECTIONS

Output connections for connecting an oscilloscope to observe waveforms of the firing pulses for the even and odd cylinders.

DC VOLTMETER CONNECTIONS

Output connections for connecting a voltmeter to measure the voltage level being generated by the magneto for the even and odd cylinders. The tip jacks should allow the use of standard voltmeter probes that are supplied with the serviceman's voltmeter.

Care and Cleaning

The 9U6958 Magneto Peak Detect Module is a durable hand-held instrument. However, since it will be used outdoors in a wide range of conditions, care must be taken to protect it and keep it clean. The case is water resistant, but not waterproof, and the 9U6958 can be damaged if water is allowed to enter the case. If moisture does enter the case, the 9U6958 should be allowed to dry out. Remove the rear cover and allow it to dry completely in a warm, dry area.


NOTICE

DO NOT use aromatic hydrocarbons of chlorinated solvents for cleaning. These chemicals will react with the plastics used in the case and cause damage.


Operating Instructions

Engine and Magneto Charts

G3500 and G3600 Firing Orders for Variable Timing Magnetos

The following tables list the firing orders for the G3500 and G3600 engines. The Magneto Peak Detect Module is labeled with an Even and an Odd Firings, or Bank, connections for the voltmeter and the oscilloscope. The cylinders that are measured for each of these connections for each magneto is also listed. It is important to note that 'even' and 'odd' descriptors do not necessarily imply even and odd cylinders, as can be seen with the G3508 and G3608. It is also important to note that on some magnetos, like the G3606 which only has one storage capacitor, all firings will be measured on the Odd Firings Connection.

G3508

Firing Order 1 - 2 - 7 - 3 - 4 - 5 - 6 - 8
Firings Measured at Odd Order Connection 1, 7, 4, 6
Firings Measured at Even Order Connection 2, 3, 5, 8
Magneto Part Number 7C6744

G3512

Firing Order 1 - 12 - 9 - 4 - 5 - 8 - 11 - 2 - 3 - 10 - 7 - 6
Firings Measured at Odd Order Connection 1, 9, 5, 11, 3, 7
Firings Measured at Even Order Connection 12, 4, 8, 2, 10, 6
Magneto Part Number 7W2171

G3516

Firing Order 1 - 2 - 5 - 6 - 3 - 4 - 9 - 10 - 15 - 16 - 11 - 12 - 13 - 14 - 7 - 8
Firings Measured at Odd Order Connection 1, 5, 3, 9, 15, 11, 13, 7
Firings Measured at Even Order Connection 2, 6, 4, 10, 16, 12, 14, 8
Magneto Part Number 7W2172

G3606

Firing Order 1 - 5 - 3 - 6 - 2 - 4
Firings Measured at Odd Order Connection 1, 5, 3, 6, 2, 4
Firings Measured at Even Order Connection
Magneto Part Number 7E8245

G3608

Firing Order 1 - 6 - 2 - 5 - 8 - 3 - 7 - 4
Firings Measured at Odd Order Connection 1, 2, 8, 7
Firings Measured at Even Order Connection 6, 5, 3, 4
Magneto Part Number 7E8246

G3612

Firing Order 1 - 12 - 9 - 4 - 5 - 8 - 11 - 2 - 3 - 10 - 7 - 6
Firings Measured at Odd Order Connection 1, 9, 5, 11, 3, 7
Firings Measured at Even Order Connection 12, 4, 8, 2, 10, 6
Magneto Part Number 7E6215

G3616

Firing Order 1 - 2 - 5 - 6 - 3 - 4 - 9 - 10 - 15 - 16 - 11 - 12 - 13 - 14 - 7 - 8
Firings Measured at Odd Order Connection 1, 5, 3, 9, 15, 11, 13, 7
Firings Measured at Even Order Connection 2, 6, 4, 10, 16, 12, 14, 8
Magneto Part Number 7C8882

DC Voltmeter Operation

To determine magneto pulses, look up engine and magneto used in the above charts.

Shutdown the engine. Disconnect the timing control cable on the back of the magneto and insert the 9U6959 T Cable in line with the timing control cable. Connect the T Cable to the input connector on the Magneto Peak Detect Module. Clip the ground wire to the engine.

Plug the black voltmeter lead into the tip jack on the front panel labelled "GND". Insert the red voltmeter lead into the tip jack on the front panel labelled "EVEN BANK" to measure the voltage being supplied during the even numbered firing pulses, 2, 4, 6, etc., of the magneto. To measure the voltage being supplied during the odd numbered firing pulses, 1, 3, 5, etc., insert the red voltmeter lead into the tip jack labelled "ODD BANK."

Set the voltmeter to the 200 VDC range and operate the engine at the desired speed and load setting to determine magneto performance. You may move the red voltmeter lead between EVEN and ODD jacks while the engine is running.

DO NOT use the SCOPE CONNECTIONS output jacks on the top panel. The voltages measured there will not be correct when measured with a voltmeter.

Ignition Voltage vs. Compression Ratio

The above chart displays the effect that compression ratios and plug gaps have on magneto performance, i.e. engine performance. The spark plug firing voltages are calculated values and represent how much voltage is needed to jump the gap. The Minimum Mag DC Voltage values are what voltages that will be measured at the "DC VOLTMETER CONNECTIONS" on the front panel.

Oscilloscope Operation

To determine magneto pulses, look in the charts for engine and magneto used.

Shut down the engine. Disconnect the timing control cable on the back of the magneto and insert the 9U6959 T Cable, in line with the timing control cable. Connect the T Cable to the input connector on the Magneto Peak Detect Module. Clip the ground wire the engine.

Connect the ground clip on the scope to the black tip jack on the top panel of the Magneto Peak Detect Module. Using a 10:1 scope probe, connect the probe to the tip jack labelled "EVEN or "ODD" depending upon which output you want to observe.

Set the oscilloscope to have a time base of 5ms/division on the screen and the voltage range to 50 V/division. The following illustrations are an indication of what the signals from the magneto should look like on the oscilloscope screen.


Magneto Firing Signals

The ODD and EVEN Scope Connections are the Inputs to the Peak Detector. The Odd signal is the same as the magneto G pin. The Even signal shows the remaining cylinders. These connections provide access to look at all cylinder firing signals with a scope. The Odd Connection signal is not necessarily the odd cylinders, but rather the odd firings in the firing order.

DO NOT use the DC VOLTMETER CONNECTIONS output jacks of the front panel. The scope traces at these connections will be DC levels only.

Troubleshooting

Instrument Check

If unit does not seem to be performing correctly do the following checks to decide what is wrong.

Disconnect the 9U6959 T Cable from the input connector on the instrument.

Using your voltmeter, perform the resistance tests outlined below in the chart.

If the measured values are different than the above described results the instrument should be returned to CSTG for repair.

T Cable Check

Disconnect the T Cable from the magneto and the timing control cable. Be sure that the T Cable is disconnected from the instrument also. Perform a continuity check on the cable using your multimeter. There should be continuity between pin C on the large male connector (9X4463), pin C on the large female connector (9X4385), and pin 3 on the small input connector (4C9810). There should be continuity between pin D on the large male connector (9X4463), pin D on the large female connector (9X4385), and pin 1 on the small input connector (4C9810). There should be continuity between the alligator clip and pin 2 of the small input connector (4C9810) and GND jacks for both DC VOLTMETER and SCOPE CONNECTIONS. See illustration below for pin locations.

Service

Before sending the instrument in for repair, be sure to perform the checks outlined in the troubleshooting section above.

If the Magneto Peak Detect Module does not work correctly, return it to the address shown below.

U.S. Mail, UPS and EMERY

AVSpare Service Technology Group
Attn: Tool Repair
100 N.E. Adams St.
Peoria, IL 61629

Telephone:

1-800-541-8665 - Inside Illinois
1-800-542-8665 - Outside Illinois
1-800-523-8665 - CanadaOutside of North America use fax 309/675-6618

Before returning the tool, be sure to enclose a letter that describes the problem and give the date of purchase from AVSpare. Tools that are less than one year old will be repaired under warranty (except for abuse). The cost of out of warranty repairs will be charged to the owner.

For information on service tools or shop supplies contact AVSpare Service Technology Group on:

AVSpare Service Technology
100 N.E. Adams Street
Peoria, Illinois 61629-9110
1-800-542-8665 (USA)
1-800-541-8665 (Illinois)
1-800-543-8665 (Canada)
404435 (Telex)
1-309-675-6618 (Fax)

or

AVSpare Service Technology
AVSpare Overseas S.A.
P.O. Box 456
1211 Geneva 6
Switzerland
41 (22) 737 40 36 (Geneva Phone)
41 (22) 737 45 44 (Geneva Fax)
AVSOVERSEA (Geneva Cable)
36CSTG (COSA E-Mail Address)

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