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[Datsun 1200 encyclopedia]

Matchbox Testing

(Difference between revisions)

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Revision as of 06:59, 18 May 2009
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Line 7: Line 7:
A volt-ohm-milliammeter (VOM) may be used to diagnose transistor ignition malfunctions. A volt-ohm-milliammeter (VOM) may be used to diagnose transistor ignition malfunctions.
-Use this scale:+Use these scales:
<br>DC: 20V <br>DC: 20V
-<br>Ohms: 1000 
<br>AC: 10V <br>AC: 10V
 +<br>Ohms: 1000
<br>Ohms: 50,000 <br>Ohms: 50,000
Line 18: Line 18:
-== Step 5 Power Supply Circuit ==+= Step 5 Power Supply Circuit =
# IGN key ON, engine not running # IGN key ON, engine not running
# connect Voltmeter (20V scale) between distributor case and the "B" connection (stem of T) # connect Voltmeter (20V scale) between distributor case and the "B" connection (stem of T)
Line 24: Line 24:
Results: Results:
* below 11.5 volts. Problem. Check fuse and wiring * below 11.5 volts. Problem. Check fuse and wiring
-* 11.5 - 12.5 volts. This test OK. Proceed to Test 6+* 11.5 - 12.5 volts. This test OK. Proceed to Step 6
= Step 6 Power Supply (Cranking) = = Step 6 Power Supply (Cranking) =
Line 34: Line 34:
Results: Results:
* Voltage more than 1V below Battery cranking voltage (or below 8.6V). Check ignition switch, fuse and wiring * Voltage more than 1V below Battery cranking voltage (or below 8.6V). Check ignition switch, fuse and wiring
-* Voltage close to battery cranking voltage (no more than 1V lower) AND better than 8.6V. This test is OK. Proceed to Test 7+* Voltage close to battery cranking voltage (no more than 1V lower) AND better than 8.6V. This test is OK. Proceed to Step 7
= Step 7 Ignition Primary Circuit = = Step 7 Ignition Primary Circuit =
Line 41: Line 41:
Results: Results:
-* below 11.5 volts. Problem. Proceed with Test 8+* below 11.5 volts. Problem. Proceed with Step 8
-* 11.5 - 12.5 volts. This test OK. Proceed with Test 9+* 11.5 - 12.5 volts. This test OK. Proceed with Step 9
- +
= Step 8 Coil Primary Circuit = = Step 8 Coil Primary Circuit =
# Key OFF # Key OFF
-# coil wire removed from coil+# Ignition Coil wire removed from coil
-#+# Ohmmeter at 1x (lowest) range
 +# Connect ohmmeter between Coil's two terminals (+ and -)
 +Results:
 +* 0.84-1.02 ohms. Ignition coil primary winding is O.K, so to solve the problem, check the ignition switch, fuse and wiring from ignition switch to coil and IC unit
 +* Less than 0.84 or more than 1.02 ohms. Coil is bad. Replace the coil.
 +*: NOTE This is for the matching "high energy" Nissan coil. If you are using the stock Datsun 1200 points-based coil, see [[Ignition Coil]]
 += Step 9 IC Unit Ground Circuit =
 +Checking "voltage drop" of the ciruit while in use.
 +
 +# Voltmeter at 20V scale
 +# Connect voltmeter between distributor case and Battery NEGATIVE terminal
 +# Crank engine and observe voltmeter
 +
 +Results:
 +* 0.5 volts or less: OK. Proceed to Step 10
 +* More than 0.5 volts: Bad ground. Check distributor ground, wiring from chassis ground to battery include cable connections
= Step 10 Pick-up Coil Resistance = = Step 10 Pick-up Coil Resistance =
 +Pick-Up Coil
 +<br>http://datsun1200.com/uploads/thumbs/1580.jpg
 +
Check the pickup resistance: Check the pickup resistance:
# Key OFF # Key OFF
Line 59: Line 76:
Results: Results:
-* It should be about 400 ohms. Proceed to Test 11+* It should be about 400 ohms. Proceed to Step 11
* If "substantially" lower or higher than 400 ohms, the pickup is either bad or a wire is pinched or shorted. * If "substantially" lower or higher than 400 ohms, the pickup is either bad or a wire is pinched or shorted.

Revision as of 07:22, 18 May 2009

How to test your 1978-1982 factory Datsun "matchbox" distributor, from the Nissan factory service manual. Matchbox is a nickname for the "IC ignition unit".

For B310 Electronic Distributor Swap
1885.jpg]

Contents

General Instructions

A volt-ohm-milliammeter (VOM) may be used to diagnose transistor ignition malfunctions.

Use these scales:
DC: 20V
AC: 10V
Ohms: 1000
Ohms: 50,000

If possible test with components at operating temperature -- this will help find intermittent problems that only occur when the parts are HOT.

It is not necessary to disconnect the harness connectors when performing the following tests.


Step 5 Power Supply Circuit

  1. IGN key ON, engine not running
  2. connect Voltmeter (20V scale) between distributor case and the "B" connection (stem of T)

Results:

  • below 11.5 volts. Problem. Check fuse and wiring
  • 11.5 - 12.5 volts. This test OK. Proceed to Step 6

Step 6 Power Supply (Cranking)

  1. Pull coil wire from cap and ground it
  2. Set Voltmeter to 20V DC scale
  3. connect Voltmeter between distributor case and the "B" connection (stem of T)
  4. Crank engine (key at START) and observe voltage

Results:

  • Voltage more than 1V below Battery cranking voltage (or below 8.6V). Check ignition switch, fuse and wiring
  • Voltage close to battery cranking voltage (no more than 1V lower) AND better than 8.6V. This test is OK. Proceed to Step 7

Step 7 Ignition Primary Circuit

  1. IGN key ON, engine not running
  2. connect Voltmeter (20V scale) between distributor case and the "C" connection (head of T)

Results:

  • below 11.5 volts. Problem. Proceed with Step 8
  • 11.5 - 12.5 volts. This test OK. Proceed with Step 9

Step 8 Coil Primary Circuit

  1. Key OFF
  2. Ignition Coil wire removed from coil
  3. Ohmmeter at 1x (lowest) range
  4. Connect ohmmeter between Coil's two terminals (+ and -)

Results:

  • 0.84-1.02 ohms. Ignition coil primary winding is O.K, so to solve the problem, check the ignition switch, fuse and wiring from ignition switch to coil and IC unit
  • Less than 0.84 or more than 1.02 ohms. Coil is bad. Replace the coil.
    NOTE This is for the matching "high energy" Nissan coil. If you are using the stock Datsun 1200 points-based coil, see Ignition Coil

Step 9 IC Unit Ground Circuit

Checking "voltage drop" of the ciruit while in use.

  1. Voltmeter at 20V scale
  2. Connect voltmeter between distributor case and Battery NEGATIVE terminal
  3. Crank engine and observe voltmeter

Results:

  • 0.5 volts or less: OK. Proceed to Step 10
  • More than 0.5 volts: Bad ground. Check distributor ground, wiring from chassis ground to battery include cable connections

Step 10 Pick-up Coil Resistance

Pick-Up Coil
1580.jpg

Check the pickup resistance:

  1. Key OFF
  2. ohmmeter between the two wires on the matchbox (red & green wires -- NOT the T-connector).
  3. set VOM to 1000 ohm scale

Results:

  • It should be about 400 ohms. Proceed to Step 11
  • If "substantially" lower or higher than 400 ohms, the pickup is either bad or a wire is pinched or shorted.


Step 11 Pick-up Coil Output

Output while cranking. Use ANALOG voltemeter.

  1. Engine at or above normal operating temperature (HOT) if possible
  2. VOM at 5V AC or 10V AC scale
  3. Connect Voltmeter to body of distributor (ground) and internal wire closest to the T-connector
  4. Remove coil wire from cap and ground it
  5. Observe analog Voltmeter while cranking engine

Results:

  • Needle wavers. OK. But if "no Spark" condition still exists, replace IC ignition unit
  • Needle steady. Problem.
    1. Check physical condition of pick-up coil and reluctor
      14075.jpg
      Reluctor (4-tooth rotating part). Stator (4-teeth ring)
    2. Check wiring and connections between coil and IC ignition unit (the matchbox)