Hi all,
TL;DR - this laptop is driving me nuts with the oddball power-related behaviors. Appreciate any insight you can provide!
I'm experiencing a power issue on an Asus Probook P5440UF-XB74. Although I've worked with electronics and computers for decades, this is my first attempt at getting into motherboard-level component troubleshooting. Any help the community can provide is greatly appreciated!
A few weeks ago I was using the laptop (on battery power) for a Zoom meeting. The battery was running very low (long meeting) but I wasn't worried about...
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Lenovo ThinkPad E480 - power LED only, no fan, no USB 5V, CPU cold (suspected power rail/fuse issue)Lenovo ThinkPad E480 - power LED only, no fan, no USB 5V, CPU cold (suspected power rail/fuse issue)
Post:
Hello,
I have a Lenovo ThinkPad E480 motherboard with the following issue.
The laptop shows only a power LED when connected to charger, but it does not boot at all.
Symptoms:- Power LED turns on
- No fan spin
- No display (internal or HDMI)
- No Caps Lock response
- CPU stays completely cold
- USB ports do not provide 5V power
Board condition:
I found corrosion around the power/PM area. I cleaned the motherboard carefully,... -
Toshiba Satellite C650-101 C650-15C C650-126 6050A2368301-MB-A02 Laptop Schematic
MANAUS 10MD2 MAS10MD2...11-01-2024, 03:13 AM -
HP Zbook 17 G6 DAXW3EMBAF0 REV F
I can't figure out the power supply system on this motherboard. There's no response and no voltage readings. Here are the measurements I took at the input.
The +VAC_IN 19V power supply from the connector goes to the three-legged transistor PQ 10009, and to the P-channel B03P03 transistors PQ10007 and PQ10006. The AC_GATE of transistors PQ10007 and PQ10006 is 6V, so the transistor is on. The VADPBL output of transistors PQ10007 and PQ10006 is 19V. This 19V then goes to transistor PQ10013, labeled
B03P03. Its PVADPTR output is 19V, and the...05-06-2026, 03:04 AM -
Toshiba Satellite A100-525 power indicator light disappears on pressing Power Button and voltages disappear except 4.5v on one pin of the battery terminal. Some like L9 shorts to ground and otherwise; capacitors - C340, C371, C98 short to ground, on-board and off-board. Please experts in the house, assist me pin down the fault. See schematic attached....