Acer Aspire 5 a515-52g, EH5AW LA-G521P Rev.1a does not start.

[andrhouseolly]

Hi goodday to all.
I really ask for help.
There are two motherboards (absolutely identical) Acer Aspire 5 a515-52g, EH5AW LA-G521P.
Both boards have exactly the same fault symptoms. It turns on, the power indicator lights up for 5 seconds, turns off (the fan does not spin).
Both boards are flashed with Bios Main and Bios EC from the “Bios Acer A515 LA-G521P FULL TEST” topic. XM25QH128AHIG replaced by W25Q128JVSIQ (also NOR-FLASH, XM was not detected by the programmer). On one of the boards, KB9022 was changed, followed by firmware. The fault persists on both boards.

The general nutrition picture is as follows:
+5VALWP (PL401) is always present when power is applied.
+3VLP is always present when power is applied.
+3VALWP (PL402) appears when the power button is pressed.
+1.2VP (PL502) appears when the power button is pressed.
Power is supplied to the Bios when you press the power button, but there is no readout (there are just high levels on the SPI bus).

More details on the levels, based on the “PWR Sequence” from the datasheet for the board:
+RTCVCC – 3V
SOC_RTCRST# - 3V
+19VB – 19V
+3VLP – 3.3V
EC_ON – 3.3V
+5VALW/+3VALW(+3VALW_DSW...) – 5V/3.3V
SPOK_3V_5V – 3.3V
+1.8VALW_PRIM – 1.8V
+1.8VALW_PG – 3.3V
+1.05VALW_PRIM – 1.1V
EC_RSMRST# - 3.3V
AC_PRESENT – 3.3V
PBTN_OUT# - 3.3V (the oscillogram matches, that is, it has a short dip when the button is pressed)
PM_SLP_S5# - does not rise (not used anywhere, only control point T84)
ESPI_RST# - does not rise
Everything else doesn't rise.

Just in case, I tried the recommendation from the topic “Acer Not Powering la-k701p” to bypass the “thermal protection”. Unfortunately, the problem has not gone away. In this version, +3VALW appears immediately when +19V power is applied (this is natural, since MAINPWON appears with KB9022, which is translated through a jumper to 3V_EN), but when you press the power button, the board also turns on without starting and turns off after 5 seconds.

Thank you. I really hope for help.

[mcplslg123]

This is not a thermal protection issue as you're getting +3VALWP.
Try removing DB2/3/4 one at a time and see if it makes any difference.

[andrhouseolly]

Thank you. I saw this recommendation in the Topic “Acer Not Powering la-k701p”,
but did not focus on it due to the fact that EC_RSMRST# is present.
I'll try this operation and update with the results.

[andrhouseolly]

I turned off DB2/DB3/DB4 sequentially, then turned it off in different combinations, also turning off all diodes.
Unfortunately, I did not get a positive result. The board does not start, shuts down after 4-5 seconds.
Signals via “PWR Sequence” remained the same, starting from PM_SLP_S5#, ESPI_RST# are missing.

[mcplslg123]

PCH does not seems to be responding at all. Whats the status of PM_BATLOW#?

[andrhouseolly]

When you press the button, the high level is 3.28v

[mcplslg123]

Everything is ok but still PCh is not answering. To me,it seems like dry PCH.

[andrhouseolly]

What possible solutions might there be?
It is very confusing that identical boards have the same fault (symptoms).
Thank you.

[mcplslg123]

If you have a bga machine,try to heat up the SOC upto 225 C with a lot of good quality bga flux. Dont attempt to do so with a heat gun or so-SOC will be permanently damaged.

This dry SOC is quite common in hp LA-G07XX series mb ,dell vegas turis 15341-1 mb. So may be/maynot be the case here.

[andrhouseolly]

Yes, I understood. that it will come to this, but this is the last stage and I really wanted to check out the “softer” options.
Unfortunately, I don’t have an infrared station for personal use, I’ll look for opportunities.
Thanks again for your help.