we were given 6 different resistors and a color code identifiication sheet for the right calculation on different resistors, and theres 4 band resistors and 5 band resistors,5 band doesnnt mean its got more resistance,it should all depends the totaly vaule of the multiplier! and for the rules of caculate the value is to look at the color band and check on the color code table we got thats got all the number value for each color,you first look at the first 2 bands and get the number down form the table and times to the 3nd band*number)and the last band is the tolerance value.
after that we had to put them in a series circuit(end to end)and measure the total combined value,the result was 2070ohms and then we put them in a parallel circuit to test the value and the result was 78,3ohms.
Sunday, May 22, 2011
Saturday, May 21, 2011
diodes
diodes practical, we first meassure the resistance in the diodes on 2k with a ohmmeter,anode to cathode is 0 ohms and same results 0 for cathode to anode.The we set on 2k ohms with another meter set on 20v to test the voltage on the meter probes, we have 0.64v so its a pass for voltage going though the binary layer of the diode,then we tested voltage on teh dioldes from both ways, anode to cathode is 0.52v and cathode to anode its infinity which means we have a working diodes. we then built a circuit with a diode and a resistor in it and test for voltage drop across the resistor and diode, 13.2v on the resistor and diode had none. then its the ampflow though the diode which is 0.01amp and voltage was 13.4v.
we then tried the same test but with a higher resistance resistor,the voltage drop on the diodes was 0.5v and voltage drop across resistor is 12.6,amp flow is 0.005amps and the result is the higher resistance there are the low amp we will get.
and at last we made a circuit with a LED we measure the voltage drop and reads 11.4v,the current going though the lED is 0.001amps and power supply is 13.39v and as result that the we get lesser voltage drop in the LED because the component in the light is a load.
we then tried the same test but with a higher resistance resistor,the voltage drop on the diodes was 0.5v and voltage drop across resistor is 12.6,amp flow is 0.005amps and the result is the higher resistance there are the low amp we will get.
and at last we made a circuit with a LED we measure the voltage drop and reads 11.4v,the current going though the lED is 0.001amps and power supply is 13.39v and as result that the we get lesser voltage drop in the LED because the component in the light is a load.
Relays
we were doing practical exercises on relays, we began reading though our notes and sample wiring diagram on how each relay works on the fuel pump in the circuit,we then did some excercise with the basics and wiring up the relays in circuits with 3 bulbs and in parallel circuit, we also did some measurements like the avaliable voltage from the circuit when its off and on. and from our result, we found that when the circuit is off there are no components using any voltage from power supply and when the circuit is on some voltage is used on the relay to charge up the internal magnet and on our results the terminal 85 has 0.14v avaliable, the bulb is connected to the terminal 85 after the consumers are connected to the parallel,atlast we draw some wiring diagram with a relay to switch with 2 lights and to the swtich of high beam and low beam.
Thursday, May 5, 2011
starter motor on bench testing and on car testing
we got given a mitsubishi M3T 49381 to pull apart and test all the components to see if they are in working conditions.
First we did a no load test on the solenoid to make sure its operating,the result for this test is 11.5v and 35.2A. then marking sectons of the starter body so we can realigned when put back together. then we take it all apart and started testing the armuture,first we did a visual inspection to check if there are any sign of overheating,burnt and any phsical damage,and there are only a few small scratches on the plate so its still serviceable,moving on to the ground circuit test by placing the black leads on the armature core the red between each of the commutator segment,result should be infinity and should have no circuit so its a pass armature,then moving on we stay placing one lead on the armture and the other one on commutator and moving the other around the commutator and see how much resistance in the circuit and we have no ohms and thats the specifications and its still serviceable,after this we meassure the diameter commutator and the undercut depth,the speciffication of a commutator should be 26.8-31mm,and our one is 20.05mm so its not serviceable and the undercut should be 0.7mm-1mm but we can only do a visual check to estimate because we dont have the tool for this test so we are moving on to the next one.
Then we placed the armture on the V block to perform a dail test and do a 360 degree turn for an acurate reading and our result is 0.05mm,specification is 0-0.2mm so ours is still serviceable.
and now its the field coil and pole shoes,we first do a visual inspection for signs of damage and we have found tears on wires and wires are loose on the coil but its still useable and then tested its resistance and showed infinity but its a pass.
And last we checked on the pinion gear and the one way clutch,first is to do a visual test for its smoothness of the movements on the shaft and also check for wares on the bushes and ours is all in good working conditions,then we reassemblred back into one piece but one of the terminals snapped off but was told to continue, and it failed on the final no load test and it could not perform.
All tests were serviceable till the final load test because of the brush came off during reasmmbling causing an incomplete circuit so it did not opereat at the end,but to solve the problem all we need to do is to replace the brush holder and it will operating properly again.
First we did a no load test on the solenoid to make sure its operating,the result for this test is 11.5v and 35.2A. then marking sectons of the starter body so we can realigned when put back together. then we take it all apart and started testing the armuture,first we did a visual inspection to check if there are any sign of overheating,burnt and any phsical damage,and there are only a few small scratches on the plate so its still serviceable,moving on to the ground circuit test by placing the black leads on the armature core the red between each of the commutator segment,result should be infinity and should have no circuit so its a pass armature,then moving on we stay placing one lead on the armture and the other one on commutator and moving the other around the commutator and see how much resistance in the circuit and we have no ohms and thats the specifications and its still serviceable,after this we meassure the diameter commutator and the undercut depth,the speciffication of a commutator should be 26.8-31mm,and our one is 20.05mm so its not serviceable and the undercut should be 0.7mm-1mm but we can only do a visual check to estimate because we dont have the tool for this test so we are moving on to the next one.
Then we placed the armture on the V block to perform a dail test and do a 360 degree turn for an acurate reading and our result is 0.05mm,specification is 0-0.2mm so ours is still serviceable.
and now its the field coil and pole shoes,we first do a visual inspection for signs of damage and we have found tears on wires and wires are loose on the coil but its still useable and then tested its resistance and showed infinity but its a pass.
And last we checked on the pinion gear and the one way clutch,first is to do a visual test for its smoothness of the movements on the shaft and also check for wares on the bushes and ours is all in good working conditions,then we reassemblred back into one piece but one of the terminals snapped off but was told to continue, and it failed on the final no load test and it could not perform.
All tests were serviceable till the final load test because of the brush came off during reasmmbling causing an incomplete circuit so it did not opereat at the end,but to solve the problem all we need to do is to replace the brush holder and it will operating properly again.
Wednesday, May 4, 2011
Alternator Off Car Testing
in this excersice we got given an alternator to dismantle it and do different tests on it to see if they works properly or not.
we follow the instrustions of the booklet,and first we took it all apart and start testing on the rotor winding ground using a muti meter set on 2k OHMs,then we put the black lead of the muti meter to the center of the rotor shaft and the red lead to the slip ring,and we should get around 2-6v as specifaction and we got 3.2v minus the internal resistance of the mutimeter and gave us 2.8 ohms at resulting a pass spec.
To the next step we go to the starter winding,to do this we place the black lead to the meter on the common terminal and the red on each of the other terminals to gain readings of each one,the spec should be 0-2ohms and we got 0.2 0.1&0.1 were the readings and they pass the specification, after this we teste the ground by placing the black lead on the body of the meter.
now we change to diode test mode to test the rectifier positive diodes, place the black lead on to the common terminal and the red to each of the ring winding on at a time. 0.580,0.590,0.579 is the result 3 of the 4 terminals and we have one with no ciruit but it should be the ground so they all pass! and then its the negative diodes, we do the same procedru but puting the red on the terminal body and the black on the terminals,and we should get the same results.
at the end this alternator is a pass after all the tests, all winding internal resistance is between specified spec.
we follow the instrustions of the booklet,and first we took it all apart and start testing on the rotor winding ground using a muti meter set on 2k OHMs,then we put the black lead of the muti meter to the center of the rotor shaft and the red lead to the slip ring,and we should get around 2-6v as specifaction and we got 3.2v minus the internal resistance of the mutimeter and gave us 2.8 ohms at resulting a pass spec.
To the next step we go to the starter winding,to do this we place the black lead to the meter on the common terminal and the red on each of the other terminals to gain readings of each one,the spec should be 0-2ohms and we got 0.2 0.1&0.1 were the readings and they pass the specification, after this we teste the ground by placing the black lead on the body of the meter.
now we change to diode test mode to test the rectifier positive diodes, place the black lead on to the common terminal and the red to each of the ring winding on at a time. 0.580,0.590,0.579 is the result 3 of the 4 terminals and we have one with no ciruit but it should be the ground so they all pass! and then its the negative diodes, we do the same procedru but puting the red on the terminal body and the black on the terminals,and we should get the same results.
at the end this alternator is a pass after all the tests, all winding internal resistance is between specified spec.
Sunday, April 17, 2011
daily report WEEK 4!
tusday april 5th
-today is the first day of electrical and electronics,we went over the laws and basic of ohms+3 triangle formula: 1 to get voltage(v)=current x resistance(R) 2: to get current is voltage/resistance and last is to get Resistance=voltag/current. We also leant how to build up a series circuit, first we connect the power souce to the board,positive wire to the fuse then another wire to the switch,a wire from the switch to the light bulb and wire back to the negative of the battery.
Later on the afternoon we built another circuit with the exact compoent but with 3 big light bulb connected,and we did a cauculation on current on all this bulbs,to measure the current in the circuit we needed the circuit to be broken and the mutimeter to be apart of the circuit. We found out that the currents are the same no matter where you test it.
wednesday april 6
-soo today is another day working circuits,we built a parallel circuit!
so first we power up the circuit board and the positive wire to the fuse and to the switch,and then we have 2 wires to the first bulb each,then from both bulb a wire connect to the negative of the battery, we also did the voltage drop and the aviable voltage on this parrallel circuit, to measure voltage in a circuit the circuit must be prarallel connected and to measure voltage drop in a circuit,and the mutimeter must connected to the input and the output of the component is measuring,and to measure aviable voltage and red and black probe needs to go to the negative and the red to the positve,likewise to avoild blowing up the fuse.
thursday april 7
-soo today we are making the logic probe,that its to check power in a power source like a battery, material used in this was a brass rod(conductor) 1 red led light and 1 green LED,a black meter 1 black alligator clip, a red alligator clip also plastic tubing. after awhile i got the probe done and tested and its ok,for this to work on the car you put the neg and pos on the neg postive on the battery.
Friday april 8
-we did both series on parallel and series into one,we put two bulbs in a parrael and one in a series,with the fuse,power and switch wires,two wires in each for the first 2 bulb,one parallel negative connect to the negative in the series bulb and back to the negative of the battery.after that we measure the resistance of each bulb using R=V/C and for watts is w=V x C. the avaiable voltage in the parallel bulbs are 8v each and none in the series circuit.
-today is the first day of electrical and electronics,we went over the laws and basic of ohms+3 triangle formula: 1 to get voltage(v)=current x resistance(R) 2: to get current is voltage/resistance and last is to get Resistance=voltag/current. We also leant how to build up a series circuit, first we connect the power souce to the board,positive wire to the fuse then another wire to the switch,a wire from the switch to the light bulb and wire back to the negative of the battery.
Later on the afternoon we built another circuit with the exact compoent but with 3 big light bulb connected,and we did a cauculation on current on all this bulbs,to measure the current in the circuit we needed the circuit to be broken and the mutimeter to be apart of the circuit. We found out that the currents are the same no matter where you test it.
wednesday april 6
-soo today is another day working circuits,we built a parallel circuit!
so first we power up the circuit board and the positive wire to the fuse and to the switch,and then we have 2 wires to the first bulb each,then from both bulb a wire connect to the negative of the battery, we also did the voltage drop and the aviable voltage on this parrallel circuit, to measure voltage in a circuit the circuit must be prarallel connected and to measure voltage drop in a circuit,and the mutimeter must connected to the input and the output of the component is measuring,and to measure aviable voltage and red and black probe needs to go to the negative and the red to the positve,likewise to avoild blowing up the fuse.
thursday april 7
-soo today we are making the logic probe,that its to check power in a power source like a battery, material used in this was a brass rod(conductor) 1 red led light and 1 green LED,a black meter 1 black alligator clip, a red alligator clip also plastic tubing. after awhile i got the probe done and tested and its ok,for this to work on the car you put the neg and pos on the neg postive on the battery.
Friday april 8
-we did both series on parallel and series into one,we put two bulbs in a parrael and one in a series,with the fuse,power and switch wires,two wires in each for the first 2 bulb,one parallel negative connect to the negative in the series bulb and back to the negative of the battery.after that we measure the resistance of each bulb using R=V/C and for watts is w=V x C. the avaiable voltage in the parallel bulbs are 8v each and none in the series circuit.
Saturday, April 16, 2011
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