| Ремонт: Ноутбуков, Компьютеров https://vlab.su/ |
|
| Hp Probook 640 G2 (Circus 6050A2723701-MB-A02) no image https://vlab.su/viewtopic.php?f=53&t=122250 |
Страница 1 из 1 |
| andromedax [ 10 янв 2022, 16:52 ] | |
| Заголовок сообщения: | Hp Probook 640 G2 (Circus 6050A2723701-MB-A02) no image |
This laptop come to me with bios chip re-soldered and probably reprogrammed It is posible that some liquid hit some parts of motherboard, but it is unlikely. There are some capacitors damaged near pwm chip "AKVG" but seems that one of the capacitors failed and burnt. I have replaced the caps and tested circuit and it is ok now. It has no video and it drains only 0.1 amps from psu. Laptop makes auto start but can be shutdown with power button. All voltages are present but not cpucore. Signal ISL95857_VR_EN is present also but there are no ISL95857_PWM_A7/ ISL95857_FCCM_A, and no H_CPU_SVIDCLK and H_CPU_SVIDDAT are present neither. I suspect that ISL95859 could be damaged. I have tested other bios dump just in case. Should I replaced the ISL95859, or need to check other voltages or signals? What do you think? |
|
| andromedax [ 18 янв 2022, 16:05 ] | |
| Заголовок сообщения: | Re: Hp Probook 640 G2 (Circus 6050A2723701-MB-A02) no image |
Hi, I have replaced the ISL95859 and nothing change, still there is no cpu vcore. I am using the schematic Quanta ZAA for reference, as it has the same pwm regulator for cpu vcore. The fact that there is no H_CPU_SVIDCLK and H_CPU_SVIDDAT makes me think that cpu could be bad. I don't know if this tho signals must be present before vcore rises. Need your help, please. Thanks in advance. |
|
| andromedax [ 22 янв 2022, 15:43 ] | |
| Заголовок сообщения: | Re: Hp Probook 640 G2 (Circus 6050A2723701-MB-A02) no image |
Seems that cpu is dead. VCCGT_SENSE is shorted to ground. Not shorted, but 3.1 ohms is like a short. This signal is feedback to ISL95859 pin 5, so it knows that something is wrong inside cpu and it cuts pwm outputs. The Quanta_Z8V mounts also this isl and is good for reference. I would like to know if someone else has found this same problem, if so, please comment. Thanks. |
|
| Страница 1 из 1 | Часовой пояс: UTC + 4 часа |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|