Acer A517-51 LA-E891P LAN+wireless adapter not working

[freeboxman]

Hello guys,

I've some issues with my laptop Acer A517-51. LA-E891P r1A

initially,I tried to insert by mistake a usb key in the RJ45 port. The realtek RTL8411b ic got very hot. the SDD m.2 was no working. I replaced the LAN controller. Now the ssd working fine, but the LAN, SD card and wireless adapter no showing in device manager. LAN is activated in bios and i treid with another wireless adapter but same issues.

I measured the voltages on the IC controller RTL8411b. Voltages missing in pins 27 and 13.

in your opinion, other things to check?

[mon2]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Hi. The links are not working.

1) Very surprised that the USB key inserting into the RJ45 caused this fault. The RJ45 is essentially a transformer and is isolated from the 'hot' voltages of the LAN interface. That is, you could short all of the RJ45 pins together without an issue.

See attached.

2) The LAN controller, if hot, perhaps should have been replaced. Are you confident the component is a known good part ? It is a PCIe device so be sure the PCIe interface legs are all good with the DC blocking caps present.

That is, when soldered in properly, with the proper pin #1 orientation of this QFN package - the Device Manager should show this PCIe device as being present. Regardless if the LAN xfmr and physical connector missing off the logic board. The PCIe LAN function should appear as a device and then install with the supporting device driver on Windows / Linux, etc. platforms.

The bottom side of this LAN IC = metal belly = pin # 49. From past experience on the XMOS user forum, this was the #1 root cause of failed PCBAs. That is, the metal belly MUST be soldered properly to allow for the component to function properly. Suggest lots of flux and direct high heat with some air pressure to melt the part into the solder bath underneath. This will create a good ground connection.

3)

Voltage of +REGOUT ?

[freeboxman]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Hello,

+regout= 1.02V

I don't know what happens, but I remember that since I tried to insert the usb key the pc has stopped working.
I forgot to specify that I changed the M.2 ssd, because the first was also shorted. I replaced it.

the LAn IC was changed by a new one bought from aliexpress. the orientation has been respected and the ground also, because most of the voltages are present except the power supply of the sd card and the VDD33 / 18 (please correct me if I'm wrong).

Schematic -> https://www.badcaps.net/forum/showthread.php?t=123071

[mon2]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Remove the M.2 SSD. It is not required to boot the laptop. At the very least, with the SSD removed, you should be able to see the POST (power on self test with memory count, text based CMOS setup key options, etc.).

With the SSD removed, does the LAN chip get hot / warm like it used to ?

Do you see any video at all at this stage ? If not, the fault is likely elsewhere. Then we should start with the basics on checking the voltage for each and every coil on the logic board when the logic board is powered with the external power adapter.

The power adapter is the original or is capable of supplying the proper current (power) for this unit ? How many watts is marked on the adapter ?

[freeboxman]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Hello Mon2,

The power adapter isn't the original one 45W, but the same amperage recommended by acer 2.37A(label on the bottom of product).

Without the SSd M.2, i've screen with acer logo and not bootable device.
The LAN chip stays cold( i think) because the board is a little bit warm when the cpu is working on. i've also boot with linux live on my usb stick. but same issue lan not detected.

if necessary, i've a bench power supply to check.

[mon2]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Do you get the Acer logo after you install the SSD ? If not, the SSD is not compatible and should be left out of the machine, for now.

[freeboxman]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Do you get the Acer logo after you install the SSD ? If not, the SSD is not compatible and should be left out of the machine, for now.

The laptop working fine with my SSD except LAN and wireless adapter not detected in operating system.

[mon2]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Both, the wireless adapter & LAN are PCIe devices.

Confirm that the attached caps are present on your board. They CANNOT be shorted or missing. Both cases will cause the observed faults.

Consider to flux and reflow each of these caps but do so with ample flux, high heat but low air pressure so that they do not go flying of the logic board.

[freeboxman]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Both, the wireless adapter & LAN are PCIe devices.

Confirm that the attached caps are present on your board. They CANNOT be shorted or missing. Both cases will cause the observed faults.

Consider to flux and reflow each of these caps but do so with ample flux, high heat but low air pressure so that they do not go flying of the logic board.

I haven't reflow the components yet, but I checked caps values on board.

The wireless adapter issue is related with the LAN chip?
Do you think the problem is the PCH itself? reflow?

[mon2]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

The caps are required for proper PCIe communication with the host (PCH) and the target devices such as the PCIe flash, wifi, BT, etc.

The cap values look ok for 0.1uf caps. Just be sure that the traces for each cap makes to the target connections. The large BGA device is responsible for the PCIe communication to assorted devices. Effectively, the laptop has multiple PCIe 'slots' like a motherboard would but for this logic board, some of the physical slots are directly connected to the chips themselves. Either way, the interface lines for data flow & clock along with the DC blocking capacitors must be present as per the PCIe specifications. They appear to be ok.

Perhaps wait on other advice but the PCH is often a show stopper for reflowing due to the size of the chip. Be sure the contacts are clean for the connectors, where present. You could use alcohol to clean them up but otherwise it may be down the large BGA device and perhaps the need to flux and reflow.

Wait for others to comment before proceeding on this task.

As noted in another thread, we recently invested into a hefty BGA rework station and only recently removed out of its crate. This table can pre-heat and work with such large or down to 0.5*0.5mm SMD devices. Hope to post a review and update once it is operational. Just fired up the power (230V) on Friday. Hope to remove a BGA this week with the tool.

[piernov]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

https://www.badcaps.net/forum/showpo...02&postcount=2

2.1. Never reflow large BGA
It won't fix the problem since 99% of the time it's not an contact issue between the BGA and the logic board. There's a high risk of damaging the board even further.
If you want to confirm if an AMD/NVidia chip is bad, you can heat it up to 200°C max for a minute and a half, no flux. It'll come back to life for a short while and then die again, because it's bad. In this case it has to be replaced.

[roxboy1984]

Re: Acer A517-51 LA-E891P LAN+wireless adapter not working

Hi, not trying to hijack but I'm having a similar issue with an Acer A315-53 the Realtek RTL8411B chip gets super hot. Any advice is greatly appreciated. I'm still learning so if someone can point me in the right direction I would really appreciate it. 🙏