Hello all,
this is my first post, so if I make mistakes please do not hesitate to point them out, thank you in advance.
I got a Dell Latitude 5420 (Service Tag: 7RFM6D3, Motherboard: GDF40 LA-491P Rev.: 2.0 (A01)) which does not start and I want to repair it. These are the symptoms:
If the laptop is only connected to the AC adapter (battery removed):
When I press the power button, the keyboard backlight and the display backlight are turning on. Caps key light is lightning, but key does not respond to pressing it.
The power/battery led is NOT showing any signal.
CPU fan is not starting.
CPU is getting warm
I tried:
I am by far no expert, but I measured the voltage at some parts and it seems, that it should be ok, at least the BIOS chip is gettin 3.3 V, the DDR4 Ram is on 1.2 V, Battery is getting 11.4 V as supposed, CMOS is at 3.07 V
The laptop uses at around 20 W when turned on, an this stays constant, so no automatic shutdown or restarting. When the battery is loading, it takes in 40 W, which seems reasonable. Battery is full and delivers 11.4 V.
I can get into the service mode by pressing B key + power button, and since then I am stuck in service mode (which basically means, the laptop does not use any energy from the battery to conduct repairs at the motherboard without removing the battery)
https://www.dell.com/support/manuals...438&lang=en-us
The Dell logo appears and that I should remove AC Adapter and press any key to continue. I do not know, if this is some kind of basic booting?....
At this point I am stuck. I inspected the motherboard and I cannot see any obvious damage, but I do not have a microscope.
The next step would be to flash the BIOS. Does this make any sense? Or should I focus more on the hardware site and e.g. find out, why the fans are not spinning at the boot process, but later they start when the CPU is getting warm?
Thank you in advance for you advice or ideas, what I can try next.
this is my first post, so if I make mistakes please do not hesitate to point them out, thank you in advance.
I got a Dell Latitude 5420 (Service Tag: 7RFM6D3, Motherboard: GDF40 LA-491P Rev.: 2.0 (A01)) which does not start and I want to repair it. These are the symptoms:
If the laptop is only connected to the AC adapter (battery removed):
When I press the power button, the keyboard backlight and the display backlight are turning on. Caps key light is lightning, but key does not respond to pressing it.
The power/battery led is NOT showing any signal.
CPU fan is not starting.
CPU is getting warm
I tried:
- External monitor -> nope
- Performing a hard reset (remove battery + CMOS battery, pressing power button for >60 secs, put CMOS back, AC adapter in, power on) -> nothing changed
- Trying out different RAM configurations (only one RAM module in the different slots etc.) -> nothing changed
- performing some Dell tests -> all successful
- https://www.dell.com/support/manuals...589&lang=en-us
- Display test was successful (LCD-BIST)
- Motherboard test was successful (M-BIST)
- I tried a Real time clock reset -> nothing changed
- I tried a BIOS Recovery following this steps:
- https://www.dell.com/support/kbdoc/e...uter-or-tablet
- But there is no BIOS Recovery screen on the display
I am by far no expert, but I measured the voltage at some parts and it seems, that it should be ok, at least the BIOS chip is gettin 3.3 V, the DDR4 Ram is on 1.2 V, Battery is getting 11.4 V as supposed, CMOS is at 3.07 V
The laptop uses at around 20 W when turned on, an this stays constant, so no automatic shutdown or restarting. When the battery is loading, it takes in 40 W, which seems reasonable. Battery is full and delivers 11.4 V.
I can get into the service mode by pressing B key + power button, and since then I am stuck in service mode (which basically means, the laptop does not use any energy from the battery to conduct repairs at the motherboard without removing the battery)
https://www.dell.com/support/manuals...438&lang=en-us
The Dell logo appears and that I should remove AC Adapter and press any key to continue. I do not know, if this is some kind of basic booting?....
At this point I am stuck. I inspected the motherboard and I cannot see any obvious damage, but I do not have a microscope.
The next step would be to flash the BIOS. Does this make any sense? Or should I focus more on the hardware site and e.g. find out, why the fans are not spinning at the boot process, but later they start when the CPU is getting warm?
Thank you in advance for you advice or ideas, what I can try next.
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