Dump nand content on working ac86u

[dominik]

Hello,
I have two ac86u routers, one of them has broken nand memory, I already order chip for replacement as well as programmer for it so I will be ready to replace nand to new one.
The question is how to get out image from working router without desoldering nand from it? Is that possible via SSH or do I have to open it, connect via UART and boot into CFE?

I know that I need to correct mac addresses when everything is finished.

 

[Anonymous34]

Hi, could you please update me if you manage to get a good dump of AC86U? I just took apart mine and I see both a UART connector and a JTAG connector. My router most likely has a bad CFE since the only LED that's on is the 4th ethernet port. Thanks!

 

[Tech9]

Stop! Your router has blown step down power converter. When I get home I’ll tell you which one exactly. Or you can search a thread called Router Temperatures - there is a picture of the component there, last few pages.

 

[Anonymous34]

Stop! Your router has blown step down power converter. When I get home I’ll tell you which one exactly. Or you can search a thread called Router Temperatures - there is a picture of the component there, last few pages.

That would be great! Saves me the trouble to source a NAND flasher and CGE. Still new with trying to fix routers and I did not find any schematics so far. Keep me posted and thanks in advance

 

[Tech9]

LAN4 lit -> MT3125 step down converter
LAN4 lit + Power LED -> you may need MT3125 + MX30LF2G18AC-TI NAND

The yellow circle is where the converter is located, marked as U355 on the PCB
The red circle is where you need 5.2V voltage to boot, 2A is enough (but see below)

You'll need hot air station to de-solder the IC and solder the new one. The IC is about $1.50, if you can find it. The other option is to build your own power supply. I had a successful boot with LM7805 fed with 19V from the main power supply, but this IC is up to 1.5A current (heats up quite a bit). This was only an experiment, no FB voltage (pin 5 on MT3125). After boot the voltage drops to about 1.2V, but still needs about 2A current.

What you usually find under the heat spreader looks like the picture below (note visually blown power converter).
If your IC looks similar, it's blown. If it looks normal, you shout read 5.2V on the inductor, or on pin 16 of the IC:

I don't think the repair is worth it though. This router has more than one issues:
https://www.snbforums.com/threads/router-temperatures.71123/page-2#post-672908

I've played with 10x broken AC86U routers about a year ago using 7x for donor parts. I had a full bin of AC86U routers. 3x came back to life, one failed again after (re-flown 2.4GHz radio IC). Not interested anymore in repairing home routers. They are all made as cheap as possible, including "high-end" models. I have one repaired AX88U (2.4GHz radio again) and some more in my collection.

Good luck!

 

[OzarkEdge]

LAN4 lit -> MT3125 step down converter
LAN4 lit + Power LED -> you may need MT3125 + MX30LF2G18AC-TI NAND

The yellow circle is where the converter is located, marked as U355 on the PCB
The red circle is where you need 5.2V voltage to boot, 2A is enough (but see below)

View attachment 39992

You'll need hot air station to de-solder the IC and solder the new one. The IC is about $1.50, if you can find it. The other option is to build your own power supply. I had a successful boot with LM7805 fed with 19V from the main power supply, but this IC is up to 1.5A current (heats up quite a bit). This was only an experiment, no FB voltage (pin 5 on MT3125). After boot the voltage drops to about 1.2V, but still needs about 2A current.

What you usually find under the heat spreader looks like the picture below (note visually blown power converter).
If your IC looks similar, it's blown. If it looks normal, you shout read 5.2V on the inductor, or on pin 16 of the IC:

View attachment 39993

I don't think the repair is worth it though. This router has more than one issues:
https://www.snbforums.com/threads/router-temperatures.71123/page-2#post-672908

I've played with 10x broken AC86U routers about a year ago using 7x for donor parts. I had a full bin of AC86U routers. 3x came back to life, one failed again after (re-flown 2.4GHz radio IC). Not interested anymore in repairing home routers. They are all made as cheap as possible, including "high-end" models. I have one repaired AX88U (2.4GHz radio again) and some more in my collection.

Good luck!

I've got two labeled 'parts' that I'll likely never use. One LED4 half-lit and one 2.4 signal that comes and goes.

Maybe the 2.4 one could be a 5.0 media bridge.

OE

 

[Tech9]

May be interesting for someone to see what usual voltage regulator IC die looks like:

It's one big transistor, taking >50% of the die surface with some control circuits around.

 

[Anonymous34]

LAN4 lit -> MT3125 step down converter
LAN4 lit + Power LED -> you may need MT3125 + MX30LF2G18AC-TI NAND

The yellow circle is where the converter is located, marked as U355 on the PCB
The red circle is where you need 5.2V voltage to boot, 2A is enough (but see below)

View attachment 39992

You'll need hot air station to de-solder the IC and solder the new one. The IC is about $1.50, if you can find it. The other option is to build your own power supply. I had a successful boot with LM7805 fed with 19V from the main power supply, but this IC is up to 1.5A current (heats up quite a bit). This was only an experiment, no FB voltage (pin 5 on MT3125). After boot the voltage drops to about 1.2V, but still needs about 2A current.

What you usually find under the heat spreader looks like the picture below (note visually blown power converter).
If your IC looks similar, it's blown. If it looks normal, you shout read 5.2V on the inductor, or on pin 16 of the IC:

View attachment 39993

I don't think the repair is worth it though. This router has more than one issues:
https://www.snbforums.com/threads/router-temperatures.71123/page-2#post-672908

I've played with 10x broken AC86U routers about a year ago using 7x for donor parts. I had a full bin of AC86U routers. 3x came back to life, one failed again after (re-flown 2.4GHz radio IC). Not interested anymore in repairing home routers. They are all made as cheap as possible, including "high-end" models. I have one repaired AX88U (2.4GHz radio again) and some more in my collection.

Good luck!

have taken off the IC, I tried wicking the pads

LAN4 lit -> MT3125 step down converter
LAN4 lit + Power LED -> you may need MT3125 + MX30LF2G18AC-TI NAND

The yellow circle is where the converter is located, marked as U355 on the PCB
The red circle is where you need 5.2V voltage to boot, 2A is enough (but see below)

View attachment 39992

You'll need hot air station to de-solder the IC and solder the new one. The IC is about $1.50, if you can find it. The other option is to build your own power supply. I had a successful boot with LM7805 fed with 19V from the main power supply, but this IC is up to 1.5A current (heats up quite a bit). This was only an experiment, no FB voltage (pin 5 on MT3125). After boot the voltage drops to about 1.2V, but still needs about 2A current.

What you usually find under the heat spreader looks like the picture below (note visually blown power converter).
If your IC looks similar, it's blown. If it looks normal, you shout read 5.2V on the inductor, or on pin 16 of the IC:

View attachment 39993

I don't think the repair is worth it though. This router has more than one issues:
https://www.snbforums.com/threads/router-temperatures.71123/page-2#post-672908

I've played with 10x broken AC86U routers about a year ago using 7x for donor parts. I had a full bin of AC86U routers. 3x came back to life, one failed again after (re-flown 2.4GHz radio IC). Not interested anymore in repairing home routers. They are all made as cheap as possible, including "high-end" models. I have one repaired AX88U (2.4GHz radio again) and some more in my collection.

Good luck!

I have worked on it for a little bit last night. While wicking the pads, I realized I was using a non leaded solder with a tiny tip. I have ripped some pads but crucially its AVIN and PG which are pin 10 and 4 respectively. Any idea if it will work without them? I also tried a tiny DC-DC converter (MP1584EN) connected to the DC jack of the router but it doesn't seem to power on, the output goes straight to 0 when connected to the inductor and LED 4 is stuck on. Resistance to ground reading on both ends of the inductor seems to be fine and not shorted

And wow, I have no idea that this router is littered with so many issues since it was positioned as a high end home router. I would probably add a couple of fans to help with the cooling if I were to get it working. No idea why Asus would choose to use 19V adapters for routers. While browsing for potential issues of the AC86U, I stumbled across AC5300's power adapter, seems to be the one included with Asus ultrabooks which is ridiculous.

 

[Anonymous34]

I've got two labeled 'parts' that I'll likely never use. One LED4 half-lit and one 2.4 signal that comes and goes.

Maybe the 2.4 one could be a 5.0 media bridge.

OE

I've got two labeled 'parts' that I'll likely never use. One LED4 half-lit and one 2.4 signal that comes and goes.

Maybe the 2.4 one could be a 5.0 media bridge.

OE

Or a wired router but there are better options out there I would say

 

[Tech9]

Any idea if it will work without them?

Try to find the reference design* and trace where the pins were connected. Restore the connections with external wiring.

* - I had it somewhere and I even posted it here on SNB, but can't find it now. It was a long time ago.

Here - https://www.m3tekic.com/filedown.ph...sb2FkLzIwMjIvMDIvMjAyMjAyMTUxMDAxNDE0NjAucGRm

 

[Anonymous34]

Try to find the reference design* and trace where the pins were connected. Restore the connections with external wiring.

* - I had it somewhere and I even posted it here on SNB, but can't find it now. It was a long time ago.

Here - https://www.m3tekic.com/filedown.ph...sb2FkLzIwMjIvMDIvMjAyMjAyMTUxMDAxNDE0NjAucGRm

Would be doing this, I think I see where the trace PG leads to, but not AVIN. Will have to probe around and see where that gets me. Thanks for your help

 

[Tech9]

Better replace the router, unless you are playing with it for educational purposes.

 

[dominik]

I don't think the repair is worth it though. This router has more than one issues:
https://www.snbforums.com/threads/router-temperatures.71123/page-2#post-672908

BTW: my routers are labelled as 19/12V and I'm using them with 12V 3A power supply, this may be an answer to Your questions about such strange voltage.

I've played with 10x broken AC86U routers about a year ago using 7x for donor parts. I had a full bin of AC86U routers. 3x came back to life, one failed again after (re-flown 2.4GHz radio IC). Not interested anymore in repairing home routers. They are all made as cheap as possible, including "high-end" models. I have one repaired AX88U (2.4GHz radio again) and some more in my collection.

Can You please share them? I already have everything except that to try to fix my broken unit.

 

[Tech9]

BTW: my routers are labelled as 19/12V

All AC86U routers I've seen were with 19V power supply. Asus specs also say 19V 1.75A.

Can You please share them?

I kept one good AC86U for my collection, recycled the rest. And it was about an year ago.

 

[dominik]

All AC86U routers I've seen were with 19V power supply. Asus specs also say 19V 1.75A.

Please take a look at attached image, its 19V 1.75A or 12V 3A.
Probably all of them were something like 5-22V and label plus power supply can be different on some regions.

I kept one good AC86U for my collection, recycled the rest. And it was about an year ago.

Ok, do You still have bin dump of nand? Have You uploaded it anywhere or to someone?
This would be for me just easier than resoldering two nands

 

[Tech9]

Please take a look at attached image, its 19V 1.75A or 12V 3A.

What year is this router?

Ok, do You still have bin dump of nand?

I never needed one. Can't help you with that, sorry.

 

[dominik]

What year is this router?

Oh, that was on that white sticker on bottom, it's 2020 (made in china). I can take more photos if You need, as well as included charger and thermal images of board if You are interested (after I replace nand).

I never needed one. Can't help you with that, sorry.

Ok, I still have another one if everything fails. Also it should be possible to dump image from CFE and upload to some tftp. Maybe somebody already have done that?

 

[Anonymous34]

Better replace the router, unless you are playing with it for educational purposes.

Update, I received the replacement IC today and replaced it today. With the ripped pad for analog voltage in, the voltage supplied to the circuit is not 5.2V. Neither does Power On Good signal connected to the board. However, the router does boot up. I will add a jumper wire down the road if the router does not go up in flames once I get a microscope.

Not using it as my main router since there are so many problems you mentioned. And besides, I am more familiar with OpenWRT than Merlin or AsusWRT. Currently serving as a Wireless AP and it performs better than the garbage DIR-850L given by my ISP. Going to use the 86U till I can afford something better or it goes up in flames.

Are there any wireless AP you'd recommend that are built better and cheap? I don't mind used as long as they are cheap. Looking to pay less than $20 for one. Will go for a x86 router soon as well since OpenVPN client is very slow on my main router (EA7500v2).

Also, seems like my CPU temperature is pegged to 120 Celsius. It should be the incorrect voltage supplied from the step down converter right? I have a fan actively running blowing on the heatsink directly. It is not in its housing since that doesn't have any EMI shield anyways. Thanks for your response again

 

[Tech9]

the voltage supplied to the circuit is not 5.2V

The output is 5.2V during boot, it drops after to I believe 1.3V, but you have to check yourself. There is info online. It's a common AC86U issue.

Looking to pay less than $20 for one.

No. Nothing in this price range, even used.

Also, seems like my CPU temperature is pegged to 120 Celsius.

Check the heatsink placement and the thermal pad underneath. If they look good, turn the router off until fully fixed. You are going to fry it.

 

[Anonymous34]

The output is 5.2V during boot, it drops after to I believe 1.3V, but you have to check yourself. There is info online. It's a common AC86U issue.



No. Nothing in this price range, even used.



Check the heatsink placement and the thermal pad underneath. If they look good, turn the router off until fully fixed. You are going to fry it.

I have a fan blowing on the rear heatsink 24/7 and the heatsink is barely warm to the touch. I think the sensor is fried since the graph shows a straight line rather than fluctuation under normal operation.

The output goes to 1.62V I believe. Not sure if that's normal.