Motion Vivian repair Head Office] Record of the V3000 does not boot repair service

Post By: mahmoud 2020-05-05

Temporary work, when receiving a client machine repair, COMPAQ’s V3000, Oh, the classic models, this machine is the most frequent failures card air welding, and surely we all know this, throw little brother had prepared for aboutBGAOf. But nothing else, looked on adjustable power supply connected to the current run 0.27, it seems not a question of graphics, current is so low. Should not be too CPU, then disassemble.Open the machine and found that this board is the 945 set was, plate number Akita. Simple test of what power each of the major power, that my judgments are right, it really is no CPU power, L28 and L26 two inductors is no PWM waveform, then the focus to the maintenance aspects of the Vcore. Akita this part of the circuit models of the Vcore is done by the MAX8736 Fengyun PWM control IC chip, measured with an oscilloscope tube Q6 on the G pole, the instantaneous power does not wave, indicating that the PWM circuit did not work, then go Check MAX8736 working conditions, first to see 8736 feet of two power supply pins 21 and 30 feet, two feet has 5V voltage. The supply of electricity is no problem, then go check the 4 pin SHDN # signal that is powered on 8736 feet, measuring voltage is only 0.8V, which is obviously wrong, the normal turn signal is 3V this is about.“Q8 d; k (z & l-v, h0 a

Be easier to find the point of failure, this board should be part of spike, and along the circuit to check CPUCORE_ON, the signal is from the TPS51120 (U35) The IC 30 feet and 11 feet to the issuance, R415 Fengyun pull measurement across the resistor, the voltage is only 0.8V or so, and R415 should be a termination voltage of 3.3V, the other end CPUCORE_ON this signal, and now pull voltage 3D3V_S0 voltage of only 0.8V, resulting in a low power signal CPUCORE_ON level, then continue to check 3D3V_S0 this voltage.

Then press the circuit to check, 3D3V_S0 by 3D3V_AUX_S5 the voltage MOS tube through U39 for this conversion, the 5678 foot measurement U39, 3.3V voltage is normal, measuring 4 feet, found that G voltage is only 0.1V, This is obviously not turn, then together to see the principle of this circuit, the actual figure since the Q15 is to do with a switch, with Q15 turn on and off, to provide to the U39 and U38 G pole control voltage . Measurement Q15, S pole voltage is 0.1V, while the S pole of the voltage is DCBATOUT to provide through R241, R241 measured at both ends, one end is 19V, the other end is 0.1V, the multimeter to the resistance to open files, the amount of R241, actually there are 35M ohm resistance, while the R241 is a 15K in the circuit resistance, it is clear that R241 has been broken, and the amount of about R243 this resistance and found that there are 15M ohm resistance, this resistance is broken, could not find 15K resistance, only to find a 330K resistor, had to use a 10K resistor for R241, after the installation of two resistors, power turn, the current run smoothly up until 1.2A, should be light machine.

Connected to the screen test machine, that actually does not shine, and then look carefully, there COMPAQ’s LOGO, but there is no backlight, but also pick up the monitor, can be displayed properly, appears to be no backlight control signals sent to, measuring a little LCD interface 34 feet BLON_OUT, voltage is 0, this is the backlight on the signal, the normal voltage is 3.3V, this signal is issued by the EC to, but the machine does not have other problems, do not bother to engage in EC, directly From there, fly wire screen over to the panel backlight is on high-voltage signal pin. This process is relatively simple, do not have text descriptions, and plug it wants.8 F; x8 O. I1 ^ + D