Asus RT-AC88U AC3100 component level board repair

[Scott Farquhar]

Hello,

Thanks in advance for your help.

I've been using this router since 2016, then as of recently it is no longer receiving power. There are no lights. I've tried 2 power adapters, and tested their voltage; the power adapters are not the issue.

The unit had a 2 year warranty, and it's been almost 3 years.

Voltage at many points on the motherboard is fluctuating. I suspect the issue might be with one of the buck converters. On the top side, there are 3 chips marked:
FR9618
G1551
L107D

The FR9618 seems to be a 23V, 3A, 340KHz synchronous step-down DC/DC converter.

There was a substantial amount of dust and possibly corrosion around 1 of the 3 ICs.

Nowhere on the board registers more than .5VDC.

According to the datasheet, this chip needs voltage flowing into it in order to allocate and disperse the voltage (and this is not the case).

The capacitors all appear to be in good condition. I haven't yet tested the Ohms of the resistors or fuses.

In the absence of a proper schematic and boardview, I'm not sure where to test from here in order to isolate the problem. Please advise.

Thanks!

 

[Grisu]

sorry to say but such units are not worth investing many hours to come to the conclusion you cant fix it.
And there are so many possibilities causing the fault. If you dont find it easily just forget it.
Sell your power adapter and maybe you get something for the not working router too.

 

[sfx2000]

Voltage at many points on the motherboard is fluctuating. I suspect the issue might be with one of the buck converters. On the top side, there are 3 chips marked:
FR9618
G1551
L107D

The FR9618 seems to be a 23V, 3A, 340KHz synchronous step-down DC/DC converter.

There was a substantial amount of dust and possibly corrosion around 1 of the 3 ICs.

Nowhere on the board registers more than .5VDC.

I think you've isolated your problem - the FR9618, as that's the primary, so if it has trouble...

 

[Scott Farquhar]

sorry to say but such units are not worth investing many hours to come to the conclusion you cant fix it.
And there are so many possibilities causing the fault. If you dont find it easily just forget it.
Sell your power adapter and maybe you get something for the not working router too.

Sorry to say...that it's "not worth investing" my time in is a completely subjective sentiment. Maybe for you it's "not worth it," but for me, fixing a $300 router with less than $10 in parts is 100% worth my time, especially considering the knowledge I'll have accrued. Of course there's many possibilities, that's how component level board repair works. If I wanted to sell the broken / partial items for parts, I wouldn't have posted on this form.

You're like someone posting "JUST TAKE IT TO THE APPLE STORE" on a tech forum. Oh, really? Thanks for that input that everyone already knew and was deliberately ignoring. Thanks for a lazy, unproductive response.

 

[Scott Farquhar]

I think you've isolated your problem - the FR9618, as that's the primary, so if it has trouble...

Thank you

 

[sfx2000]

Thank you

Looks like one can find that part over on Aliexpress - so depending on your skill and tools available, should be an easy fix, so worth trying - if you have access to a Metcal, this is a super easy job.

 

[Grisu]

Sorry to say...that it's "not worth investing" my time in is a completely subjective sentiment. Maybe for you it's "not worth it," but for me, fixing a $300 router with less than $10 in parts is 100% worth my time, especially considering the knowledge I'll have accrued. Of course there's many possibilities, that's how component level board repair works. If I wanted to sell the broken / partial items for parts, I wouldn't have posted on this form.

You're like someone posting "JUST TAKE IT TO THE APPLE STORE" on a tech forum. Oh, really? Thanks for that input that everyone already knew and was deliberately ignoring. Thanks for a lazy, unproductive response.

HAHA, where do you see a 300$ router, cant find it, sorry???
I get it NEW for 180€ (free delivery) and used about 100-150. https://www.ebay.de/itm/ASUS-RT-AC8...289975&hash=item340c12db36:g:rjgAAOSwefldAgAD

Yours is definitely USED and repaired not worth 300 you payed years ago!

 

[Smokindog]

You obviously have done your homework but I still want to ask the captain obvious question, .... did you test the output of your wall wart before anything else? Sorry, I only know that I often forget some of the most basic of things once I begin my detailed plan of attack

And I agree with you. If it's my time and I enjoy what I'm doing and I'm learning it's not being wasted. I reload my own ammunition and I have people telling me I'm not saving any money, I'm wasting my time, blah blah blah. Last time the shelves were bare of factory stuff I was out shooting, they weren't

 

[sfx2000]

@Scott Farquhar - don't worry about the side comments - and many of those comments do not reflect the general gist of the community here at SNBForums.

Sidenote - one can help by not responding in a negative view there - just don't worry.

Once you get the part, and replace, please follow up, as this might be useful to others.