STARTER MOTOR BENCH TESTING AND REPAIR
Must wear overalls and steel cap work boots at all time when we doing testing and repair.
Equipments: starter motor, multimeter, armature grolwler, test light, sockets, screw drivers.
First we tested the starter motor on the test bench, carried out a no load test to see if the starter in good working condition. We mounted the starter onto the test bench, connected all wires, turn the machine on, voltmeter showed12.18V (spec >= 11V), clampmeter showed 38.8A (spec 30 to 50A), means the starter in good working condition.
Then disassenmbled the starter by frollowing the sequence shown in our work book.
Next we visual inspected the armature, to see if there is any signs of overheating, burning, physical damage of poling, the one we were working on shows everything in good condition.
After that we use a multimeter in ohms range, put leads on commutator segments and armature core or shaft to check if they connect to each other, all readings shown infinity matched the specs.
Then put meter across each of the armature segments to check the continuity between all segments, meter was shown 0ohms, matched the factory specs.
Next measured the conmutator diameter and checked the mica undercut depth of the armature, our armature got 32mm in diameter and 1mm of mica undercut with in the factory specs.
After that we did the ground test and continuity test again by using the test light, to see if there is any short or open curcirt.
Once we finished the armature, we visual inspected the field coil and pole shoes, all in good condition.
Then we checked the continuity in the field windings by place the probles on each end of the field winding. We found the grounded winding shown infinite and not grounded winging shown 0ohms.
After that we measured the length of brushes, all four of them have good length of 15mm, and tested the brush holder, to see if two of them grounded and other two not shorted to ground.
Then we carried out a solenoid testing. First we tested the pull in winding by connecting 9V power supply to S and M terminals, the plunger been pulled in and current draw was shown 20A. Then tested the hold in winding by connecting 9V power supply to S terminal and solenoid body, the plunger remain in until we disconnect the power, and showed 8A current draw.
Last we checked pinion gear and one way clutch and brushes, they all in good condition.
Once we finished all the testing, we reassembled it back by reversing the proceduce we disassemble the starter and put it back onto the test bench, the starter motor running no problem and showing 13.2V voltage and 38A current.
From the bench testing and repair I understand when we servicing starter motor we need check if there is and wear and damage on the body before take it apart.
- A continuity test between the ends of field windings to check if there is any open circuit (reading needs less than 0.2ohms)
- A test for ground between end of filed windings and body to see if there is any shorted circuit (reading should be infinite).
- All segments on armature must be connected to each other in closed circuit (resistance between 0-1ohms) and not connect to any of the armature core of shaft (reading should be infinite).
- Commutator should be checked for wear segments (refer to SPEC).
- Brushes need in good length, and should be no continuity between insulated bursh holders and grounded brush holders.
- One way clutch and pinion gear should turn freely in running direction and in good condition.
- Solenoid needs to have a factory spec current draw to pull in the plunger and a factory spec current draw to hold in the plunger.
STARTER MOTOR ON CAR TESTING
Equipments: vehicle with a pre-engage starter motor, multimeter, clamp meter.
We tested the starter motor on car to see how ti works. The motor that we tested from a Mazda 323, 1981-1985, with no transmission and not requires a power source for save its memory.
First we carried out some visual checks on the motor and meter, make sure everything in good condition.
Then we checked the battery OCV voltage 12.88V, means the battery in 100% charge. After that we checked the cranking voltage of the starter motor showed us 11.18V above of spec of 9.5V.
Next we performed voltage drop tests of different parts in starting system, battery positive terminal and solenoid input got 0.2V, solenoid input and output got 0.1V and battery negative and starter motor body got 0.2V, and calculated the total voltage drop in starting system was 0.5V within the sepc.
Last we tested the current draw of starter motor when it is cranking, meter showed us 128.7A, with in the spec of 125-175A.
From this test, I understand when the starter operate on car, it should spin at a good speed and the voltage drop of starter motor should not be less than 9.5V, the voltage drop of the whole circuit should be a maximum of 0.5V, and the current draw from the battery needs to be with in the factory spec.
Tuesday 29 March 2011
Thursday 24 March 2011
AUTOMOTIVE BATTERY
This week we learned how to test the automotive battery and tested the the battery on car.
First day we tested a battery off car. The battery made by LUCAS, battery number is 128HD, cold cranking amps is 400A, conventional type.
Before we start the test, we need to carry out some visual checks first to see if any corrosion under mounting clamp, terminals clean and tight, clamp bolts tight and no electrolyte leakage on case. The battery that we were testing had no problem.
A hydrometer has been used to test the electrolyte in the battery, because the electrolyte contants H2SO4, we need to put on a pair of safety glasses and wearing gloves before remove the battery cell covers, and need to know where is the closest water supply if and accident happened.
After remove the battery cell caps, we need to check the electrolyte level in each cell first. All six cells were showing a high level.
Then we tested the open circuit voltage of that battery, was showing 6.60V, refer to the table in our test book, we can find this battery was under 25% charge, as we know the battery must be over 50% charged 12.4V before we can continue the testing. We put the battery back onto the charger and changed to another one.
The hydrometer designed to do the battery electrolyte specific gravity test, we put the hydrometer front end into each of the battery cells, sucked up about half tube of electrolyte, checked the reading and coulor showing in the hydrometer. The readings are, 1.250(white), 1.225(red), 1.250(white), 1.300(green), 1.200(red), 1.200(red), the battery sepccific gravity variation we tested is 100 point. But the allowable spec is 25-50 points, that means the battery has failed this test.
After the off car testing, we moved on to the on car testing of the battery. The battery we were tesing made by LUCAS, number NS40ZLG for a 1998 mazda demio, CCA 310.
Before start testing we also carried out a visual check like the off car testing. That battery was in good condition, no corrosion, all bolts tight, terminals clean, and no leakage on case.
Checked all six battery cells level in high level, we performed an ocv test, reading was 12.6v, more than the half charge spec 12.4v, that means the battery in good working order. After that, we tested the spec gravity by using the hydrometer, all readings between 1.235 to 1.265 and showed green in colour.
Last test was the high rate discharge test, we hooked on the load test onto the battery and applied a current of 155A, which is half of the CCA of that battery, the voltage of that battery was hold above 10.6V.
From the battery testing, I found when we work with batteries, we need to make sure put all safety equipments on, perform visual check first, electrolyte must at high level other wise fill it up with still water. the ocv must more that 12.4v, and spec gravity reading needs between 1.235 to 1.265, high discharge test needs to know the cca rate before put the load on, and load only can put on less than 15sec, if any of these tests failed, the battery either needs to be charged or needs to be replaced.
First day we tested a battery off car. The battery made by LUCAS, battery number is 128HD, cold cranking amps is 400A, conventional type.
Before we start the test, we need to carry out some visual checks first to see if any corrosion under mounting clamp, terminals clean and tight, clamp bolts tight and no electrolyte leakage on case. The battery that we were testing had no problem.
A hydrometer has been used to test the electrolyte in the battery, because the electrolyte contants H2SO4, we need to put on a pair of safety glasses and wearing gloves before remove the battery cell covers, and need to know where is the closest water supply if and accident happened.
After remove the battery cell caps, we need to check the electrolyte level in each cell first. All six cells were showing a high level.
Then we tested the open circuit voltage of that battery, was showing 6.60V, refer to the table in our test book, we can find this battery was under 25% charge, as we know the battery must be over 50% charged 12.4V before we can continue the testing. We put the battery back onto the charger and changed to another one.
The hydrometer designed to do the battery electrolyte specific gravity test, we put the hydrometer front end into each of the battery cells, sucked up about half tube of electrolyte, checked the reading and coulor showing in the hydrometer. The readings are, 1.250(white), 1.225(red), 1.250(white), 1.300(green), 1.200(red), 1.200(red), the battery sepccific gravity variation we tested is 100 point. But the allowable spec is 25-50 points, that means the battery has failed this test.
After the off car testing, we moved on to the on car testing of the battery. The battery we were tesing made by LUCAS, number NS40ZLG for a 1998 mazda demio, CCA 310.
Before start testing we also carried out a visual check like the off car testing. That battery was in good condition, no corrosion, all bolts tight, terminals clean, and no leakage on case.
Checked all six battery cells level in high level, we performed an ocv test, reading was 12.6v, more than the half charge spec 12.4v, that means the battery in good working order. After that, we tested the spec gravity by using the hydrometer, all readings between 1.235 to 1.265 and showed green in colour.
Last test was the high rate discharge test, we hooked on the load test onto the battery and applied a current of 155A, which is half of the CCA of that battery, the voltage of that battery was hold above 10.6V.
From the battery testing, I found when we work with batteries, we need to make sure put all safety equipments on, perform visual check first, electrolyte must at high level other wise fill it up with still water. the ocv must more that 12.4v, and spec gravity reading needs between 1.235 to 1.265, high discharge test needs to know the cca rate before put the load on, and load only can put on less than 15sec, if any of these tests failed, the battery either needs to be charged or needs to be replaced.
Sunday 20 March 2011
CHARGING SYSTEM
March 15 2011 - March 16 2011
This week we learned the alternator off car testing and the charging system on-car testing.
ALTERNATOR OFF CAR TESTING
First day we disassembled an alternator to see how it works and tested all important parts of the alternator.
Equipments are, adigital multimeter, alternator, screw drivers, sockets.
To disassemble an alternator, we need to follow the directions in a service manual just like the procedure in our pratical book.
After we removed the rear cover, brush holder, rectifier, and regulator, we tested the rotor winding to ground and the rotor winding internal resistance.
To test the rotor winding to ground, we set the meter on 2k ohms, place black lead on the centre of the rotor shaft and red lead on the positive slip ring, the meter reads infinity, because there should be an open circuit otherwise the rotor winding has shorted to ground need to replace it.
Then we set the meter on 200 ohms to test the internal resistance of the rotor winding by place one end of each lead on each slip rings, the meter reading was 3.5 ohms, we can find the reading specification is 2 to 6 ohms.
Next we removed the back cover of the alternator, found there are four terminals. First we need to find the common point which is the terminal has most wires attached, then we measured the resistance of each stator winding by touching each terminal and the common point, the actual reading are 0.2 ohms for all three terminals, within the spec reading, means there is no problem of the stator winding.
After that we tested if the stator winding contected to the ground by place the meter leads on the common point and the alternator body, there should be no circuit between the winding and ground. The reading was infinite which is a pass.
Once we done that, we moved on to test the rectifier. Diodes in the rectifier makes the current only can go one direction. Faulty diodes in an rectifier reduce current and voltage output.
There are two sets of diodes in one rectifier, positve diodes and negative diodes. As we know the current in a working diode should only can go one direction. We set the meter on diode test mode, to test the positive didoes, place the common lead on output terminal and positive lead on each input terminal, the resistance was low, around 0.52VD, when we reverse that, the reading was infinite. To test the negative didoes, we found readings were opposite to the positive diodes, the reading tells us all the diodes on the rectifier are working good.
The next testing was the voltage regulator, the voltage regulator controls the output of the alternator by controlling the strength of the magnetic field produced by the rotor. Procedure for testing the voltage regulator, first we need to find out the regulator spec's, the one I was testing the part number is 0170, field setting A, Voltage 12V, and Set point spec 14.5V. Then contected the regulator on to the tester by refer to the diagram for this regulator, after we turn the tester on, the short circuit light was off, warning ligh was stay on, field light flash continuously, and set point voltage reading was 14.5V, that means this regulator is working properly.
The last thing we did was measure the brush protrusion length, it is important because if the protrusions are too short, brush springs can not apply enough pressure to maintain the contact, may reduces the output of the alternator. To measuring that we just use an ruler to measure the length of the brush protursion, both protrusions on the brush we tested was 9.0mm which are more than the minimum length of 4.0mm.
After tested all the parts of the alternator, we assemble the alternator back on and tested it to see if it is working properly.
CHARGING SYSTEM ON-CAR TESTING
Second day of this week we tested and learned how the charging system works on-car.
From the charts in the workshop, we found the charging system that we used from a MAZDA 323 1981-1985.
First thing we need to do was remove the sureface charge of the battery by turn the fan on for serval minutes. Then we contect the voltmeter across the terminals of the battery, with the engine off. The reading was 12.5V whick means the battery in good condition and fully charged.
After that, we start the engine and let it run at about 1500rpm - 2000 rpm, contect the voltmeter across the terminals of the battery got a no-load voltage reading 14.5V. As we know the no-load voltage increases should between 0.5 to 2.0 volts. If the reading higher than that, means something wrong with the regulator, if the reading same as the open circuit voltage, means the charging system not working properly.
Once we finished the no-load test, we contected a load test onto the battery with engine running at about 2000rpm, increased the load in the system to 100amps dc, the voltage dropped to 13.0V and the amp meter reading was 29.1amps, which told us the charging system is supply current to the electrical units and charging the battery.
The last test was the voltage drop test. we used the voltmeter tested the voltage drop before and after the alternator when the engine was running to see if there is any resistance in the system. the reading was 0.017V between battery postive to the alternator output, and 0.02V between battery negative and alternator body. Then we calculated the total volts droped 0.037V, within the maximum allowed 0.40V.
This week we learned the alternator off car testing and the charging system on-car testing.
ALTERNATOR OFF CAR TESTING
First day we disassembled an alternator to see how it works and tested all important parts of the alternator.
Equipments are, adigital multimeter, alternator, screw drivers, sockets.
To disassemble an alternator, we need to follow the directions in a service manual just like the procedure in our pratical book.
After we removed the rear cover, brush holder, rectifier, and regulator, we tested the rotor winding to ground and the rotor winding internal resistance.
To test the rotor winding to ground, we set the meter on 2k ohms, place black lead on the centre of the rotor shaft and red lead on the positive slip ring, the meter reads infinity, because there should be an open circuit otherwise the rotor winding has shorted to ground need to replace it.
Then we set the meter on 200 ohms to test the internal resistance of the rotor winding by place one end of each lead on each slip rings, the meter reading was 3.5 ohms, we can find the reading specification is 2 to 6 ohms.
Next we removed the back cover of the alternator, found there are four terminals. First we need to find the common point which is the terminal has most wires attached, then we measured the resistance of each stator winding by touching each terminal and the common point, the actual reading are 0.2 ohms for all three terminals, within the spec reading, means there is no problem of the stator winding.
After that we tested if the stator winding contected to the ground by place the meter leads on the common point and the alternator body, there should be no circuit between the winding and ground. The reading was infinite which is a pass.
Once we done that, we moved on to test the rectifier. Diodes in the rectifier makes the current only can go one direction. Faulty diodes in an rectifier reduce current and voltage output.
There are two sets of diodes in one rectifier, positve diodes and negative diodes. As we know the current in a working diode should only can go one direction. We set the meter on diode test mode, to test the positive didoes, place the common lead on output terminal and positive lead on each input terminal, the resistance was low, around 0.52VD, when we reverse that, the reading was infinite. To test the negative didoes, we found readings were opposite to the positive diodes, the reading tells us all the diodes on the rectifier are working good.
The next testing was the voltage regulator, the voltage regulator controls the output of the alternator by controlling the strength of the magnetic field produced by the rotor. Procedure for testing the voltage regulator, first we need to find out the regulator spec's, the one I was testing the part number is 0170, field setting A, Voltage 12V, and Set point spec 14.5V. Then contected the regulator on to the tester by refer to the diagram for this regulator, after we turn the tester on, the short circuit light was off, warning ligh was stay on, field light flash continuously, and set point voltage reading was 14.5V, that means this regulator is working properly.
The last thing we did was measure the brush protrusion length, it is important because if the protrusions are too short, brush springs can not apply enough pressure to maintain the contact, may reduces the output of the alternator. To measuring that we just use an ruler to measure the length of the brush protursion, both protrusions on the brush we tested was 9.0mm which are more than the minimum length of 4.0mm.
After tested all the parts of the alternator, we assemble the alternator back on and tested it to see if it is working properly.
CHARGING SYSTEM ON-CAR TESTING
Second day of this week we tested and learned how the charging system works on-car.
From the charts in the workshop, we found the charging system that we used from a MAZDA 323 1981-1985.
First thing we need to do was remove the sureface charge of the battery by turn the fan on for serval minutes. Then we contect the voltmeter across the terminals of the battery, with the engine off. The reading was 12.5V whick means the battery in good condition and fully charged.
After that, we start the engine and let it run at about 1500rpm - 2000 rpm, contect the voltmeter across the terminals of the battery got a no-load voltage reading 14.5V. As we know the no-load voltage increases should between 0.5 to 2.0 volts. If the reading higher than that, means something wrong with the regulator, if the reading same as the open circuit voltage, means the charging system not working properly.
Once we finished the no-load test, we contected a load test onto the battery with engine running at about 2000rpm, increased the load in the system to 100amps dc, the voltage dropped to 13.0V and the amp meter reading was 29.1amps, which told us the charging system is supply current to the electrical units and charging the battery.
The last test was the voltage drop test. we used the voltmeter tested the voltage drop before and after the alternator when the engine was running to see if there is any resistance in the system. the reading was 0.017V between battery postive to the alternator output, and 0.02V between battery negative and alternator body. Then we calculated the total volts droped 0.037V, within the maximum allowed 0.40V.
Friday 11 March 2011
CIRCUITS
March 9 2011 - March 11 2011
First week of 4841 Electrical & Electronics, we learned some basics of electrical and circuits.
The basic elements of electricity are Volts, Ohms, Amps and Watts. Volts is the pressure to make electrons move in a circuit; Ohms is the resistance to reduce the current flow and voltage in a circuit; and Amps is how many and how fast the electrons can move in the conductor; Watts is the unit of how much work has been done.
After we known these basic things of electricity, we moved on to several types of electrical circuits.
Before we set up some electrical circuit, there are several things that we need to know, how to measure Available Voltage, Voltage Drop, Amps, and Resistance.
-Available Voltage is the voltage that is availabe for a consumer to use, we use black lead of a multimeter attach to good earth, and positive lead attach to the point we need to measure.
-Voltage Drop is how many voltage that been used by a components in a circuit, that we use the meter leads touch the wires on both sides of the component in circuit.
-To measure the Ohms of a components, we need to separate it from the circuit, and use red lead touch the positive side and black lead touch the negative side of the component.
-To measure the amperage in circuit, first we need to move the positive lead into the DC amp position, then we must brake the circuit and use the red lead touch positive side and black lead attach negative side of the circuit, so the current can flow into the meter.
First week of 4841 Electrical & Electronics, we learned some basics of electrical and circuits.
The basic elements of electricity are Volts, Ohms, Amps and Watts. Volts is the pressure to make electrons move in a circuit; Ohms is the resistance to reduce the current flow and voltage in a circuit; and Amps is how many and how fast the electrons can move in the conductor; Watts is the unit of how much work has been done.
After we known these basic things of electricity, we moved on to several types of electrical circuits.
Before we set up some electrical circuit, there are several things that we need to know, how to measure Available Voltage, Voltage Drop, Amps, and Resistance.
-Available Voltage is the voltage that is availabe for a consumer to use, we use black lead of a multimeter attach to good earth, and positive lead attach to the point we need to measure.
-Voltage Drop is how many voltage that been used by a components in a circuit, that we use the meter leads touch the wires on both sides of the component in circuit.
-To measure the Ohms of a components, we need to separate it from the circuit, and use red lead touch the positive side and black lead touch the negative side of the component.
-To measure the amperage in circuit, first we need to move the positive lead into the DC amp position, then we must brake the circuit and use the red lead touch positive side and black lead attach negative side of the circuit, so the current can flow into the meter.
SAFETY
March 8 2011
The first day of 4841 Electrical & Electronics, the most important thing that we talked in the class is SAFETY.
Each of us received a copy of Safety Briefing need to sign when we known all of the things on that sheet.
The key points of safety when we work in a workshop is PPE(Personal Protection Equipment) including safety boots, overall, safety glasses, etc.
Other potential risks and hazards that we need to know in work shop like, do not remove and cap or strews that contants hot or high pressure fluid; some of the parts can be really hot after use; always use axle stands or drive-on ramps when the car been raised up; never smoke in the workshop; need to take care of electrical overload, short-circuit or the electric shork etc.
The first day of 4841 Electrical & Electronics, the most important thing that we talked in the class is SAFETY.
Each of us received a copy of Safety Briefing need to sign when we known all of the things on that sheet.
The key points of safety when we work in a workshop is PPE(Personal Protection Equipment) including safety boots, overall, safety glasses, etc.
Other potential risks and hazards that we need to know in work shop like, do not remove and cap or strews that contants hot or high pressure fluid; some of the parts can be really hot after use; always use axle stands or drive-on ramps when the car been raised up; never smoke in the workshop; need to take care of electrical overload, short-circuit or the electric shork etc.
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