DEll D600 DC 1.05V 1.2V CIRCUIT FAST TEST WAY

Power management chip PU2 (MAX1715) output DC 1.05V voltage (VTT,test point 1), and DC 1.2V voltage (VCC_1_2_MCH, test point 2)....read more

IBM THINKPAD T60 CLOCK CIRCUIT FAST TEST WAY

The clock circuit has a few power supply points, DC 3V voltage (VCC3B, test point 1 and 2)

L13 inductor, the resistance value about 0 ohm (test point 3)....read more

IBM THINKPAD T60 DC CHARGING CIRCUIT FAST TEST WAY

Input DC 20V (VINT20, test point 1), after power management chip U42 (MAX8765) processing, output DC 12V voltage (CHARGER_OUT12, test point 2) to charge.

Complementary push-pull circuit Q4A Q4B, opposite phase PWM  pulse signal to control mosfet (test point 3). Look at their waveform on the picture....read more

IBM THINKPAD T60 DC 1.8V 0.9V CIRCUIT FAST TEST WAY

Input DC 20V (VINT20, test point 1), after power management chip U7 (MAX8632) processing, output DC 1.8V voltage (6A VCC1R8A, test point 2).

12-Pin of U7 (MAX8632) output DC 0.9V (VCC0R9B, test point 3).

Complementary push-pull circuit Q43 Q49, opposite phase PWM  pulse signal to control mosfet (test point 4). Look at their waveform on the picture.....read more

IBM THINKPAD T60 DC 1.5V 1.05V CIRCUIT FAST TEST WAY

Power management chip U29 (MAX1540ETJ) output DC 1.5V voltage (VCC1R5M,test point 1), and DC 1.05V voltage (VCC1R05B, test point 2).

Complementary push-pull circuit, opposite phase PWM  pulse signal to control mosfet (test point 3). Look at their waveform on the picture.

U29 25-Pin control the G pole of Q14 Q90 upper mosfet, .... read more

IBM THINKPAD T60 DC3V 5V CIRCUIT FAST TEST WAY

DC 20V ( test point 1) from DC input circuit, through power management chip U41 ( MAX1901), after processing, output DC 3V(test point 2) and DC 5V(test point 3) voltage.

Complementary push-pull circuit,...read more

HP DM1 Laptop Doesn’t Boot, +VCC_CORE Voltage Missing

A HP laptop doesn’t boot, press power button, the current 0.35A stopped, According to experience, doubt power supply for cpu problem. So test +VCC_CORE (PL13), found +VCC_CORE voltage missing. Observe carefully, there is a small hole on the lower mosfet PQ26, it was damaged. Removed PQ26, test the resistance between PL13 inductor and gnd, the value is normal.

So, replace a new PQ26, connect power and boot again, the current still is 0.35A and stopped. Touch power ic RT8165B, very hot, suspected it was damaged, so replace a new RT8165B. Boot again, the current 0.20A stopped, +VCC_CORE voltage missing, yet. Take the schematic diagram, test +VIN, VCC, PVCC, EN, etc,...read more