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Old 11-30-2021, 09:12 PM   #1
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Join Date: Feb 2020
City & State: Noosaville
My Country: Australia
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Posts: 309
Default Dell Inspiron 13 5379 not starting heads up

I had a Dell Inspiron 13 5379 brought in with little signs of life. No response to power button. Motherboard fitted was Dell part no: 00KJ0J; the following schematics were available and matched up.

No RSMRST_PWRGD# was traced back to the 1D0V_S5 supply being missing. At one point the machine booted up ok during probing, only to return dead when the board was screwed back in. There was evidence that the owner had been quite rough with this lappie, screen was broken and mounts for the battery all broken. The hinges for the screen were also quite stiff.

So I was looking around PU5201, and checked the other side of the board. I noticed that PC5204 (bootstrap capacitor for PU5201) looked a bit odd. I wasn't sure if it was corrosion so scraped it with my tweezers. The cap moved at one end so was partially detached from the pad. The cap measured 0.1uf (schematic says 1uf, however datasheet for the AOZ2262QI IC says 0.1uf). I replaced it anyway. Machine booted up straight away.

So the reason for this post is to give a heads up to others. The design of this lappie allows a lot of torsional stress on the motherboard as it isn't that rigid. The cracking of the cap solder joint says as much. So something to look out for on this model particularly with components in the middle of the board.

One other thing to note is that since the CMOS battery is on a daughterboard, you will be clearing the BIOS back to defaults when removing the board. When I booted the machine up, I was met with a Bitlocker screen on his drive. The TPM keys were still intact but it was because the BIOS reset defaults PTT (TPM) and Secure Boot to OFF. You will need to re-enable these to get your system booting Bitlocker encrypted drives without a recovery key.
Attached Images
File Type: jpg PC5204 broken joint.jpg (302.4 KB, 12 views)
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