Hello,
first of all I want to apologize for my bad English, but I try to give my best.
Customer brought me a laptop, which is charging the battery (when the dc-jack is connected) but don't power up when the power-button was pressed down. Only the white LED lights up, and you can hear a short noise in same interval when power-button was pressed and hold for longer timer. The customer changed already battery and dc-power-adapter.
For this laptop the correct shematic is the service manual "Clevo NH50ER NH57ER NH50EPS NH57EPS - 6-71-NH5S0-D02 Schematic".
I dissembled the motherboard and removed all connectors and pressed the power button. Under the thermal camera, I could see that the dual-channel load switch with part number U67 (its an EM5290) was getting hot and had make the noises in the same interval. So I measured on power controller TPS51275B-1RUKR that I only got VDD3 with 3.3V on coil and 3VS, but no VDD5 for 5V on coil and no 5VS. The voltage will increase but is getting stopped by a dead short on 5VS-rail. Because of that, I removed the EM5290 to isolate the short and the wonderful thing is, without it, the laptop is getting power and boot up completely (so I think it can´t be a big problem) but the fans aren´t spinning so the laptop is overheating and is shutting off after a while.
Now I have a few questions:
- After removing the EM5290 I still don´t get VDD5 with 5V on coil PL20 until I press the power button. Then the voltage will show up and is holding the 5V. Is it normal? I think yes, because on last page of service manual there is a boot-sequence which is showing 5V (but not VDD5) after pwr_btn.
- I try to inject voltage on PIN 13/14 and 8/9 of EM5290 on motherboard and on other components for 5VS but only the point where I inject the voltage is heating up. The voltage is draining down and current goes straight to max (resistance is zero). How can I find the faulty component with this conditions?
- I replaced EM5290 already with new one at first, because i hoped maybe its a low resistance rail.
- There a some bypass capacitors and mosfets/transistors which are connected with ground. I already removed a few components and put it back. Does someone have an idea which components in a case like this are often failure? I don´t want to remove more components blind.
- Is it correct that 5VS (I think it means standby and is the same like always on) is here only on mDP, HDMI, audio codec, fans and rgb keyboard? Because the laptop will boot without 5VS so important components can´t be bad.
If someone need more informations or needs the schematic to help me, feel free to ask.
Thanks in advance!
first of all I want to apologize for my bad English, but I try to give my best.
Customer brought me a laptop, which is charging the battery (when the dc-jack is connected) but don't power up when the power-button was pressed down. Only the white LED lights up, and you can hear a short noise in same interval when power-button was pressed and hold for longer timer. The customer changed already battery and dc-power-adapter.
For this laptop the correct shematic is the service manual "Clevo NH50ER NH57ER NH50EPS NH57EPS - 6-71-NH5S0-D02 Schematic".
I dissembled the motherboard and removed all connectors and pressed the power button. Under the thermal camera, I could see that the dual-channel load switch with part number U67 (its an EM5290) was getting hot and had make the noises in the same interval. So I measured on power controller TPS51275B-1RUKR that I only got VDD3 with 3.3V on coil and 3VS, but no VDD5 for 5V on coil and no 5VS. The voltage will increase but is getting stopped by a dead short on 5VS-rail. Because of that, I removed the EM5290 to isolate the short and the wonderful thing is, without it, the laptop is getting power and boot up completely (so I think it can´t be a big problem) but the fans aren´t spinning so the laptop is overheating and is shutting off after a while.
Now I have a few questions:
- After removing the EM5290 I still don´t get VDD5 with 5V on coil PL20 until I press the power button. Then the voltage will show up and is holding the 5V. Is it normal? I think yes, because on last page of service manual there is a boot-sequence which is showing 5V (but not VDD5) after pwr_btn.
- I try to inject voltage on PIN 13/14 and 8/9 of EM5290 on motherboard and on other components for 5VS but only the point where I inject the voltage is heating up. The voltage is draining down and current goes straight to max (resistance is zero). How can I find the faulty component with this conditions?
- I replaced EM5290 already with new one at first, because i hoped maybe its a low resistance rail.
- There a some bypass capacitors and mosfets/transistors which are connected with ground. I already removed a few components and put it back. Does someone have an idea which components in a case like this are often failure? I don´t want to remove more components blind.
- Is it correct that 5VS (I think it means standby and is the same like always on) is here only on mDP, HDMI, audio codec, fans and rgb keyboard? Because the laptop will boot without 5VS so important components can´t be bad.
If someone need more informations or needs the schematic to help me, feel free to ask.
Thanks in advance!
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