hp Pavilion 14 CE-1XXX 5 fast 3 slow blinks or cmos checksum error if restarted immediately after shutdown or suspend

[Caimano]

hp Pavilion 14 CE-1XXX
MB G7AD-2G DAG7ADMB8D0 REV D
Processor i5 8265U

AFAIK schematics or boardview are not available for this MB, but I used a similar board as a reference (G7AL-2G)

Laptop came in not booting with caps lock blinking 3 fast- 2 slow indicating RAM error. Charging works fine. Found bad soldering on the only ram socket present (2 outer left pins and 2 outer right pins).
Once soldered the laptop started fine and I was able to install Windows 11, upgrade BIOS to version F30 from Windows without a problem, BUT I found a strange and annoying problem.

If I start the laptop immediately after the shutdown or the suspend (within 5 seconds) most of the time the laptop stops with the caps lock blinking 5 fast- 3 slow. After soft reset (power button pressed more than 6 seconds) the laptop starts and boots normally. A few times instead of the 5-3 blink the laptop showed a CMOS checksum error and asked to press enter to reset BIOS config : after reset the laptop boots fine.

If I wait at least 10 seconds before restarting or resuming the laptop starts and boots fine.
The problem is the same with or without the AC adapter.

I replaced EC chip twice (1 x IT8987E-BXA and 1 x IT8987E-BXS), tried a different battery (both supply RTC voltage =3.22V and rtc clock is not lost), RAM stick, disk, USB port, display, keyboard, power connector.

I flashed 2 different versions of BIOS from HP site with clean ME (and updated to latest version from Windows). Same problem. Once started the laptop works just fine.

Any clue or anything to check?
Thanks in advance

[MOD EDIT] Link to schematic - https://www.badcaps.net/forum/troubl...00-dag7almb8c0

Reminder: rules and organization of this section - https://www.badcaps.net/forum/troubl...f-this-section

[mcplslg123]

Make sure the suffix of EC is same as original. Like BXA suffix should be replaced with BXA only and not BXS. Though not much information is available about the suffix version differences,as per some sources A stands for "Always" while S stands for "Suspend". So may give unexpected behaviour.

However, if you replaced with the same suffix,then dont have much to suggest other then checking LIDSW#

[Caimano]

Update : Lidsw# works fine and reacts as expected when opening/closing lid.
I found a thing I've never noticed, but I don't know if it is relevant for the problem : when the system shuts down te 3.3V and the 5V remain on for about 6 seconds (more or less the time I have to wait to be sure that the restart will work Unfortunately while you can control to wait a while before restarting, you cannot control the timing of auto restart after Windows updates, Bios, updates and so on).

Anyway I tried to change the EC chip, and Ram again but same problem.

As the last shot I will try to replace the BIOS chip itself. Waiting for new chip.

[Caimano]

I flashed and verified a new BIOS chip just arrived from China Winbond 25Q128FV . I replaced the original 25Q128JV with this chip, but the pc does not start (no fan and power led blinking). The difference between FV nd JV chips seems to by a slightly higher max frequency spec for JV's, but I doubt laptops work at such high frequency. Maybe the new chip is fake. Anyway I ordered new 25Q128JV and I will give it a try.

[Caimano]

I received and programmed the new 25Q128JV chip but the problem is still the same: pc boots and works fine, but after shutdown if restarted within few seconds from power off the laptop stops with the caps lock blinking 5 fast- 3 slow. After soft reset (power button pressed more than 6 seconds) the laptop starts and boots normally. A few times instead of the 5-3 blink the laptop showed a CMOS checksum error and asked to press enter to reset BIOS config : after reset the laptop boots fine. If I wait at least 10 seconds before restarting or resuming the laptop starts and boots fine.
Since I am running out of ideas I am giving up and selling the pc as defective.

[Caimano]

Before selling the laptop for parts I decided to give it one more try. I checked the resistors around the BIOS chip and I found that the pullup resistors on the HOLD pin and on the WRITEENABLE pins had an abnormal resistance. After replacing them with one KOhm resistors the problem was solved 👍👍👍😎

[Dr.d]

Nice work finding the problem....what a weird issue. Just curious how far off the values were?

[Caimano]

Nice work finding the problem....what a weird issue. Just curious how far off the values were?

They were in the 100K range and probably the 2 active low lines were kind of floating causing the random malfunction. You are right saying it was a weird issue because in my experience a resistor gets damaged (open or higher resistance value) when a high current flows through it and I can't imagine how this could happen on these two lines (maybe a previous repair attempt?). Anyway I am happy that everything works now.