Part 3 of tutorial video of repairing adaptor is finally ready! In this we explain the function of primary and secondary circuits and also error correction and compensation in switching circuits. Before repairing adaptor make sure to read the article bellow and be careful and cautious.
And also be sure to check the first and the second parts of adaptor repairing for better understanding
Important tips on Laptop Adapter Repair
Observe safety precautions
Consider two important points before opening the adapter cover
1- Make sure the power cable (you're using) is healthy and OK. You can ensure the health of the cable by checking ohm, or you can just use another healthy cable.
2- Check ohm of the output jack of the adapter while it's disconnected from power so that you'll diagnose disconnection or short circuit of output cable.Ohm that's around zero (on both sides of the multimeter's probe) indicates short circuit and very high ohm (almost infinite) means that the output cable is disconnected. In this case, changing the output cable will solve the adapter problem. The correct ohm of output cable is almost like the diode test (meaning, low ohm on one way, and high ohm on the other way will appear)
Important tips after opening the adapter cover
1- Make sure the adapter is disconnected from the AC power and continue the process observing safety precautions.
2- First of all and before doing anything, discharge the probable voltage of the main capacitor (C1) which is the biggest capacitor on the circuit, with a suitable resistor (3K3 to 100K with a minimum power of 2W resistor)
3- Observe with your eyes. Some failures are visible to the eyes. Identify and troubleshoot them. For example, one of the secondary filter capacitors (C4 or C5) is inflated (bumped). Change the failed capacitor and before connecting adaptor to power socket, make sure of health of rectifier Diode in secondary of power (D6) with ohm check and then connect adaptor to power socket and test. Or, if the input fuse is badly burned, do not connect adaptor to power immediately after changing the fuse. Be sure to ohm check the AC input block (Diode bridge: D1 , main capacitor: C1 and power MOSFET: Q1) for short circuit. And if the circuit is not shorted, test the adaptor with a 200W bulb after changing the fuse.
But if you don't see any burned components, be sure to ohm check the important elements before troubleshooting according to the recommended algorithm in order to save your time (before checking ohm, make sure adaptor is not connected to AC power and the main capacitor is discharged) the important components to ohm check include: D2, R4, R5, R6, NTC, F1, D1, Q1, D3, D4, - in the primary of power and D6 in the secondary block- and the transformer.
Important tips after repairing adapter (before tightening the cover and applying adhesive)
1-Do not at all plug the adapter into the laptop for testing immediately after repairing. First, make sure of the steps below and then plug it:
2-Make sure PCB is OK in terms of soldering. If necessary, renew solder the damaged and suspicious tins.
3- Make sure the cable and the output jack are healthy and OK (ohm check them)
4- Amperage consumption test (load): Take a look at the output amperage of the repaired adapter which is written on the cover. Connect a consumer to the adapter output so that more current than the written amperage would be consumed from it. For example, if the written amperage is 1.8A, then consume 2A of the adapter. And at that time (in that state), measure the output voltage (capacitor C4 or C5) and the main capacitor voltage (C1). If you noticed a remarkable voltage drop on these capacitors, change the capacitors and test amperage consumption again.
5- Final Test: Test the adaptor for at least half an hour. Meaning connect a consumer that consumes the current (that's written on the adapter cover) from it.
(For example, for the adaptor we are discussing about, connect a 12V bulb to the output) and now cautiously, check the generated temperature of the primary power elements Q1 and the secondary D6. If the temperature is too high, repeat the troubleshooting.
6- Caution: (while the adapter is turned ON):
And do not touch the primary block's heat sink (Power MOSFET heat sink) because the heat sink might not be isolated and connected to the GND of the primary block of power, (in that case) which will then have 110V power. (meaning, half the input power).
B: If possible, use a thermal sensor to test the temperature of the primary heat sink, otherwise, disconnect the adaptor power to check temperature (with your hand).
C:Never touch both primary and secondary heat sinks simultaneously because in addition to the risk of electrocution, the primary and secondary GNDs may connect (which are isolated from each other) and damage the adaptor.
D: Completely observe all the safety precautions!
Video Size: 959 MB
Video Time: 48:00
PDF files related to the video ( Attached )
And also be sure to check the first and the second parts of adaptor repairing for better understanding
Important tips on Laptop Adapter Repair
Observe safety precautions
- AC voltage, adaptor input and DC voltage of primary block of switching power are fatal and dangerous. So do not forget to be cautious while working.
- If possible, insulate the floor of the repair shop (pave the floor with insulator floor covering) or at least insulate under the chair of your work area. (About one square meter).
- Do NOT use metal desk and chair at all.
- Make sure that the work area and your body would NOT be moist (wet) while working, dry them completely.
- Take care of the metal tools and objects on your work desk.
- Use 200 watt bulb while testing adaptor (which we've taught how to make it before)
- Do NOT forget to discharge the main capacitor (C1)
- while working with measuring instruments (multimeter- Oscilloscope), choose the right (suitable) range. (Because of high voltage of the primary block)
Consider two important points before opening the adapter cover
1- Make sure the power cable (you're using) is healthy and OK. You can ensure the health of the cable by checking ohm, or you can just use another healthy cable.
2- Check ohm of the output jack of the adapter while it's disconnected from power so that you'll diagnose disconnection or short circuit of output cable.Ohm that's around zero (on both sides of the multimeter's probe) indicates short circuit and very high ohm (almost infinite) means that the output cable is disconnected. In this case, changing the output cable will solve the adapter problem. The correct ohm of output cable is almost like the diode test (meaning, low ohm on one way, and high ohm on the other way will appear)
Important tips after opening the adapter cover
1- Make sure the adapter is disconnected from the AC power and continue the process observing safety precautions.
2- First of all and before doing anything, discharge the probable voltage of the main capacitor (C1) which is the biggest capacitor on the circuit, with a suitable resistor (3K3 to 100K with a minimum power of 2W resistor)
3- Observe with your eyes. Some failures are visible to the eyes. Identify and troubleshoot them. For example, one of the secondary filter capacitors (C4 or C5) is inflated (bumped). Change the failed capacitor and before connecting adaptor to power socket, make sure of health of rectifier Diode in secondary of power (D6) with ohm check and then connect adaptor to power socket and test. Or, if the input fuse is badly burned, do not connect adaptor to power immediately after changing the fuse. Be sure to ohm check the AC input block (Diode bridge: D1 , main capacitor: C1 and power MOSFET: Q1) for short circuit. And if the circuit is not shorted, test the adaptor with a 200W bulb after changing the fuse.
But if you don't see any burned components, be sure to ohm check the important elements before troubleshooting according to the recommended algorithm in order to save your time (before checking ohm, make sure adaptor is not connected to AC power and the main capacitor is discharged) the important components to ohm check include: D2, R4, R5, R6, NTC, F1, D1, Q1, D3, D4, - in the primary of power and D6 in the secondary block- and the transformer.
Important tips after repairing adapter (before tightening the cover and applying adhesive)
1-Do not at all plug the adapter into the laptop for testing immediately after repairing. First, make sure of the steps below and then plug it:
2-Make sure PCB is OK in terms of soldering. If necessary, renew solder the damaged and suspicious tins.
3- Make sure the cable and the output jack are healthy and OK (ohm check them)
4- Amperage consumption test (load): Take a look at the output amperage of the repaired adapter which is written on the cover. Connect a consumer to the adapter output so that more current than the written amperage would be consumed from it. For example, if the written amperage is 1.8A, then consume 2A of the adapter. And at that time (in that state), measure the output voltage (capacitor C4 or C5) and the main capacitor voltage (C1). If you noticed a remarkable voltage drop on these capacitors, change the capacitors and test amperage consumption again.
5- Final Test: Test the adaptor for at least half an hour. Meaning connect a consumer that consumes the current (that's written on the adapter cover) from it.
(For example, for the adaptor we are discussing about, connect a 12V bulb to the output) and now cautiously, check the generated temperature of the primary power elements Q1 and the secondary D6. If the temperature is too high, repeat the troubleshooting.
6- Caution: (while the adapter is turned ON):
And do not touch the primary block's heat sink (Power MOSFET heat sink) because the heat sink might not be isolated and connected to the GND of the primary block of power, (in that case) which will then have 110V power. (meaning, half the input power).
B: If possible, use a thermal sensor to test the temperature of the primary heat sink, otherwise, disconnect the adaptor power to check temperature (with your hand).
C:Never touch both primary and secondary heat sinks simultaneously because in addition to the risk of electrocution, the primary and secondary GNDs may connect (which are isolated from each other) and damage the adaptor.
D: Completely observe all the safety precautions!
Video Size: 959 MB
Video Time: 48:00
PDF files related to the video ( Attached )
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