Toshiba L600 Water Damaged Laptop

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n the morning, I received the machine from a colleague. He said that the customer had repaired the machine at someone else's house, and it didn't work after half a month. Yes, I got the machine, there are no screws on it , I opened it in a few minutes, it turns out that water has entered the inside, but it has been treated very well, and many resistors and capacitors inside have been welded, it seems that the cheapness is not good Here we go. I can't help but feel a little disappointed. There is no business today, so I have to pick up the phone, so I stay on the plane. Said to find out the problem and give him a reply, and then tell him how much it costs. The colleague left, and found the drawing number TE2. SB welded. The BIOS has been soldered. The crystal vibrates.

3 The 5-volt chip has been touched. Of course, the water inflow area seems to be very large, and the corrosion is very serious, so first add welding, cleaning, etc. to the place that should be welded. 35 volts has power. The switch has power and jumps, the inductance is normal to the ground, the crystal oscillator of the EC has a voltage difference, and there is no short circuit. You can only check one by one.

Firstly, it is tested that the transition of NBSWON# from the switch to the EC is normal. 95 feet jump to normal

According to the timing of this machine, the output should be S5-ON, but there is no response when measuring pin 26, ha ha. Immediately cut off the power and measure the ground, 770. It is normal. Then quickly measure the EC conditions. The power supply is 3.18 volts, the clock is available, and the reset is available. ACIN 2.66 volts, LID 0 volts. ? 0 volts? Is it so lucky? Immediately cut off the power and measure the ground, 003. Hehe , so lucky, directly find the source of this LID

MR1 analysis, it may be that this MR1 ​​is broken, and this is also the hardest hit area. Remove it directly, and then measure the ground, more than 700, my God, no way, so cheap, find the same material board. Find this outfit. Then turn on the power, press the switch and there is no response, then test again. The 26-pin S5-ON is still motionless. It's all right, as expected, and then turn on the power to measure the LID of pin 93. It is already 3.1 volts. 

But why is it still not triggered? Think about the BIOS being soldered. Then brush it again, after the brush is finished, the fault remains. Thinking about the conditions of this EC , there are not many measurements.Then test the RSMRST to the ground and it is normal. Could it be that the EC is broken? There is no way to find an EC to replace it. Power on the test again. 26 feet still not moving? then I wondered if the BIOS was flashed incorrectly? "I found another one from the Internet and installed it, but the fault still persists, 55555. Sad. . . Could it be that the chip is not welded well, and then measure the voltage . Measure it. 2.88 volts. 2.88. Not just now. How many volts is 3.1? Why only. 2.88. Could it be that my soldering is broken, or where am I connecting the pins ? a magnifying glass.No problem, look at this EC power supply by one. The resistor of 2.2 is directly pulled to the 3VPCU, this must be done. 3.3 volts, by the way, I remembered, why was the voltage here before the EC was changed. 3.1 few and not. 3.3, there must be 3.3 on the inductance, by the way, the resistor, find R583

Measure the next set of values. More than 100, haha. It seems that my luck has been so good. Find it now. 2.2 resistor installed. Reconnect the power and turn on the current. 003 remained motionless . test it first. 26 feet this this S5-ON. It has happened, and my heart is finally at ease. Then according to the sequence S5 voltage will be turned on. Directly find the S5 voltage 0 volts, as expected, huh, huh . That. The S5 is turned on, but the S5 voltage is not. It is easy to say, find it first. 15 volts can be seen. Because many of the Quanta boards are not powered by 15V. Measure it.15 volts is already normal, then find that the S5D signal is 0 volts. 

Find PQ18.G extremely voltage. If the connection is not disconnected, then you can find PR175 directly. It turned out that the resistors were seriously blackened. Heh Ke, find a 1M one and replace it, and when I change it, I find that the solder pads at one end are gone. Connect it with a wire, and then turn on the power. . The current suddenly jumped to 0.8 and stopped. Hey, why are there so many questions, this kind of question is the most annoying . Tested. CPU reset. The SPD of the memory is normal, and it suddenly occurred to me that someone else has touched the SB BIOS.After swiping it, there is no hope. Connect the power and turn it on, and the current will go up, and then connect the screen, and turn it on as expected, but the result is still displayed.

Lenovo Y460 Y460P Common Problems

 Both Y460 and Y460p are divided into two types: thin screen and thick screen. The screen cables look the same, but they are not universal. If they are interchanged, they will short-circuit. 

The interface between the Y460 Y460P screen cable and the motherboard is easy to burn out. This kind of fault encounters several screen cable interfaces that are all burned. If you press the side of the switch bezel when the power is on, it will also cause a short circuit on the screen cable interface below. If you are lucky, you can still see smoke and smell burning, but the machine is still bright!! ! ! ! ! ! ! ! ! ! 

Both Y460 and Y460P have found a common problem, that is, the phenomenon of dark screen, whether it is a thick screen or a thin screen, the cause of the

The problem is ridiculous, so when you encounter a machine with a dark screen, don't rush to remove the screen Check the circuit, the problem is likely to be on the switch bar, because the standby chip on the switch board is the dark screen caused by the damage of the magnetically conductive triode. I tested and researched and removed nearly 30 bad switch bars, and the dark screen was almost all. is bad this one.
Detection method: Press the power button to turn on the machine. If the screen is dark, remove the switch board and the screen should light up.

Solution: If there is no replacement chip, you can just remove the triode directly, and the big deal is not to wait.

ACER 4741G Wistron JE40- CP

I haven't posted a notebook repair post for many days, and I am busy with data recovery all day long. The year is coming to an end, and the apprentices are going back to set up shop. They are usually responsible for the maintenance of these machines, but now I have to do it myself. Basically, I have to repair 5 boards every day. Today I will choose an interesting one and write a post. Let's get down to business. Model: ACER4741G Motherboard :

Wistron
JE40- CP
Architecture: I3+HM55+NV independent display

Fault description: There is a standby current when it is powered on, and it does not trigger. It does not trigger on the surface, but in fact there is already a trigger action, and the current jumps from 0.02 to 0.05 repeatedly.

To repair this kind of failure, I usually don't look at the drawings, because it is better to have a picture in my heart than to look at a picture! From the previous fault description, we know that the standby condition of the machine is Basically Met. The Oscilloscope Can Directly Measure the 3V 5V Standby or The Pin1 Pin of the EC ROM Has Data Transmission. O 0.05 After Pressing the Switch, Which FURTHER ProVES that there is no problem why can't the current rise? We know that Wistron has a 3V 5V standby-to-run voltage conversion MOS similar to Quanta. We first measure whether the MOS outputs 3V 5V correctly after triggering. As shown below:

The picture shows the voltage after the 3V voltage has been switched by the MOS. It is obviously wrong. The maximum value is only 2.48V and this waveform has been maintained. It can be seen that his control level waveform is also wrong, as shown in the figure below:

The control stage and the output stage are equal, and the same is true for the measurement of the 5V voltage. We often encounter this in the maintenance of Wistron and Quanta boards. 90% of them are short circuits in the rear stage, but there is no serious short circuit. We can check it with a meter. Use the ground resistance to judge which path is short-circuited. Here we only use an oscilloscope for the whole process. How to use an oscilloscope to determine whether this short circuit
is a 3V load short circuit or a 5V load short circuit, in fact, you only need to measure the 3V 5V standby voltage waveform. As shown below:

The figure shows the waveform of the 3V standby voltage, which is normally flat and does not appear in the picture, but the waveform of the 5V standby voltage is flat, which proves that it is a short circuit caused by a 3V load. Next, use the burner directly The position can be accurately judged by using the method, and the adjustable power supply is connected to the 3V switching MOS, and the high current is directly adjusted to 3.3V, and the fault point can be found quickly by touching it with hands.

The final failure point of the machine in this case is caused by the leakage of the C359 small capacitor in the above picture. This failure can be repaired by directly removing it. The whole board repair takes less than 5 minutes. Faults are accurate to a single point.

Case Study 1

 Resistance Resistor

Capacitance: Capacity

Inductance: Inductance

Diode: Diode

Triode: triode

Field tube: field effect transistor FET

There are also certain rules to follow for the identification of components on the main board: (All the screenshots are from CT3 material board)

1. The logo of the resistance contains the letter "R"

In addition, there are thermistors marked with RT or RH at the beginning.
2. The logo of the capacitor contains the letter "C"

3. The logo of the inductance contains the letter "L"

4. The logo of the diode contains the letter "D"

 

(1) PD25 and PD26 in the above figure are single diodes. Using the forward conduction characteristics of the diodes, the conduction value measured on the main board with the diode position (the multimeter is: FLUKE15B the same below) is 228, and the components are removed to measure Value: 260 Carefully observe that pin 1 and pin 2 of PD22 on the motherboard are connected, so it is also a single diode. The conduction value measured online is 125, and the measured value is 133 when removed

(2) PD34 is a dual diode. Its internal structure may have the following situations:

             When ABC
is measured online with a diode file, touch any two feet with black and red test leads, and there are readings in the six measurements. It seems that the online measurement is not accurate at this time. Either the component is damaged, or the reading on the multimeter is affected by the peripheral circuit. Remove the D34, and there are two readings in the six measurements: when the red pen is connected to pin 3 and the black pen is connected to pin 1, the reading is 557; When the red pen is connected to pin 2 and the black pen is connected to pin 3, the reading is 553.

According to the forward conduction characteristics of the diode, this double diode belongs to the "end-to-end connection" type, that is, type A
(3)

In the above figure, the types of the double-diode PD30 and PD40 can be measured online, which are B type and A type respectively. 5.
The identification of the triode and field effect tube on the main board contains the letter "Q"

 

On the reverse side of this part is a power management chip MAX1999, which controls two PWM circuits. Combined with the tinfoil wiring on the motherboard, it can be determined that this is part of a PWM circuit. PQ154 and PQ155 are the upper and lower tubes, and they are single MOS tubes.

Take off PQ154 and PQ155 respectively, and measure D and S poles alternately with black and red test leads. When the red test lead is connected to the S pole and the black test lead is connected to the D pole, there will be readings: the reading of the upper tube is 510, and the reading of the lower tube is 189. Both are N-channel single MOS transistors. The silk screen mark on the surface of the upper tube is 4800B, and the silk screen mark on the surface of the lower tube is 4702. The materials used for the upper and lower tubes are different. Observe the periphery of PQ142 and the corresponding reverse side. This tube should be a dual-channel MOS tube of another PWM circuit controlled by MAX1999.

After measurement, it is found that S1 is grounded, and S2 is connected with D1. Therefore, it can be visually understood that the left half of the PQ142 in the above figure is the upper tube, and the right half is the lower tube.
Next, judge the type of PQ142, as shown in the figure below, use a camera and ferrochrome to pry open D1 and D2 of PQ142, so that these four feet are separated from the pad.

 

Adjust the multimeter to the diode level:

(1) When the red pen is connected to D1 and the black pen is connected to S1, the reading is infinity; when the red pen is connected to S1 and the black pen is connected to D1, the reading is 173.

(2) When the red pen is connected to D2 and the black pen is connected to S2, the reading is infinity; when the red pen is connected to S2 and the black pen is connected to D2, the reading is 485. It can be known that PQ142 is a dual N-channel MOS transistor.

 

Observe that the four pins 1, 2, 5, and 6 of PQ127 in the above figure are connected, which conforms to the characteristics of a single MOS tube. Press the MOS tube directly to measure. The four pins connected are the D pole, the 4 pins are the S pole, and the 3 pins are the G pole. After measurement, when the red pen is connected to the S pole and the black meter is connected to the D pole, the reading is 520. Therefore, it is an N-channel six-pin MOS transistor

 

The observations of the sesame tubes Q54 and Q55 in the above picture are fruitless. It may be a triode or a field effect transistor. It can be assumed that it is a triode to measure, take it off and measure any two pins alternately with red and black test leads, and there is only one reading: when the red pen is connected to pin 1 and the black pen is connected to pin 3, the reading is 598, which can be judged as N ditch Dojo effect tube. Carefully observe the surface of the components, the silk screen code is "W2E", so we can know that all the components on the motherboard are N-channel field effect transistors.

In the picture above, MQ1 looks like a field effect tube (not necessarily true), take it off and measure the diode value of any two pins alternately with red and black test leads. There are two readings in the six measurements: when the red pen is connected to pin 2 and the black pen is connected to pin 3, the reading is 586; when the red pen is connected to pin 2 and the black pen is connected to pin 1, the reading is 600. It can be inferred that MQ1 is an NPN transistor.

 

According to the silkscreen, the sesame tube in the picture above is Q33, measure according to the above method: connect the red pen to 3 pins, the black pen to 2 pins, the reading is 639; the red pen to 1 pin, the black pen to 2 pins, the reading is 641. It can be inferred that Q33 is a PNP transistor.

 

Q40 in the above figure should be a field effect tube after observation. After measurement, when the red pen is connected to D pole (pin 1, 2, 5, 6), and the black pen is connected to pin 4, the reading is 418. Therefore, the component is a P-channel field effect transistor.
The observation of Sesame tube Q41 was fruitless. It may be a triode or a field effect transistor. It can be assumed that it is a triode to measure: in the road test, use the red and black test leads to measure any two pins alternately, and the readings are infinite. Take it off and get the same result. Chatto learned that it has integrated resistors inside. It seems that this method is not suitable for all triodes.

 

In addition, the components marked with the letter "U" on the motherboard are integrated ICs. Some are easy to distinguish, for example: the south bridge on the CT3 material board is marked as U40, the north bridge is marked as U38, the EC mark is U23, the card reader chip is marked as U21, the marks of sound card, power amplifier, MODEL, network card, EEPROM, power management chip, etc. Both contain the letter "U". Of course, there are still some components marked with "U" that are not easy to identify. For example, there is a five-pin chip marked with U near the two USB ports of the CT3 material board.

 

 

Carefully observe the above figure, the first pin of U33 is connected with the first pin of the USB interface through the 0-ohm resistor R682. It can be seen that this five-pin chip provides power for USB.

 

Seeing U1, U2, three 0-ohm resistors, and three triodes, it is natural to think of the R, G, B and line and field signals of VGA. If U1 and U2 are gates, their pins should be connected to the row and field pins of VGA. Adjust the multimeter to the diode level, connect one test lead to pin 13 of the VGA interface, and draw the other test lead on the pins of U1 and U2, and find that the first pin of U2 is

The value of pin 4 and pin 13 of the VGA interface is 17; similarly, the value of pin 4 of U1 and pin 14 of the VGA interface is 17. On the front and back of the VGA interface, it is found that the resistance marked 390 is connected between them.

Also near the South Bridge, we can also find two five-pin chips with the letter "U" in their logo

It can be known from experience that the function of the two five-pin chips is to convert the reset signal sent by the south bridge.

In short, for the identification of components on the motherboard, there must be not only relevant theories as the basis, but also rich maintenance experience as the foundation.

Acer V193HQV Monitor Dead Condition Repair

Customer gave Acer V193HQV Monitor for service. Dead Condition

 

Checked Power Cord with multi meter working fine. then decided to open the back case. 

Checked mainboard Section "TOP258PN" IC Burnt. 

Changed With New IC.Monitor Working Fine.