TP-Link Archer C3200 Blown Power Input - Page 1
Forum section: electronics / repair

author: spoon
author_rank: Newbie
timestamp: June 28, 2018, 04:27:36 am
content: Hi all,I picked up a TP-Link Archer C3200 for cheap because it "wouldn't power on." I was (perhaps somewhat naively) hoping that it would be something as simple as a blown SMD fuse or similar that I could easily fix. However, when I opened the unit up, I found that it had suffered some sort of massive power spike (lightning strike maybe?) and had apparently burnt up a number of components near the DC input.After cleaning up the effected area, according to the PCB labels, it seems that the missing components are two pairs of SMD ferrite beads and a small SMD capacitor. I searched for any sort of service manual or even photos of the same/similar boards for reference, but had no luck. Does anyone have any advice on how I could figure out the values of these components? Would it be that critical to find exact matches? It also seems that there is a short to ground somewhere on the board that I'll have to chase down, so hopefully it's not a complete waste of time anyway. I appreciate any input though!I've attached a couple photos for reference.Thanks!

author: stj
author_rank: Super Contributor
timestamp: June 28, 2018, 06:22:15 pm
content: check for shorts across the pads and across those polymer caps.something destroyed those inductors - they dont fail without a lot of help.

author: wraper
author_rank: Unknown
timestamp: June 28, 2018, 06:30:06 pm
content: Seems like previous owner cut off a "faulty power plug" and plugged wires directly into the mains socket. In the past I've seen one such Nokia phone with evaporated traces. Strangely phone still worked fine, except charging. While being completely ridiculous, people doing this sort of idiocy is not that rare as you might think.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: June 28, 2018, 07:37:48 pm
content: Looks pretty bad but it if not multiplayer board i think it is repairable.I do not have schematic but it could be possible to questimate the needed components maybe someone who is professional can give some further advise.

author: Gyro
author_rank: Super Contributor
timestamp: June 28, 2018, 07:44:50 pm
content: Quote from: Bashstreet on June 28, 2018, 07:37:48 pmI quite like the concept of a "multiplayer board", it certainly works as a descriptive term for what several people have found on used test gear here - "someone's messed with this before!"P.S. Yes I agree, that looks like 'mains damage' not lightning.

author: wraper
author_rank: Unknown
timestamp: June 28, 2018, 07:46:33 pm
content: Quote from: Bashstreet on June 28, 2018, 07:37:48 pmDunno, I'd guess that DC/DC converters are dead and circuit they are powering likely as well.As of broken traces near connector, it's not a big issue.

author: spoon
author_rank: Newbie
timestamp: June 29, 2018, 04:30:56 am
content: Thanks for the replies, everyone. I'll attempt to hunt down the short and keep searching for similar boards I can reference for the missing components. If nothing else I suppose it will be a good learning experience.

author: Rasz
author_rank: Super Contributor
timestamp: June 29, 2018, 05:32:00 am
content: Quote from: spoon on June 28, 2018, 04:27:36 amnah, I would too for something like <=$5missing components are non critical, just input filtering, what you need to check is anything behind them fried and/or passed current even higher. There are at least three buck converters on the pcb.- take off radiators- check for shorts between ground and all the inductors/electrolytic caps-read markings on the buck converter chips, U5 etc

author: bd139
author_rank: Super Contributor
timestamp: June 29, 2018, 09:58:08 am
content: C3 / C4 look like they are across the input and haven't blown. Bet this was reverse polarity using the wrong adapter that caused the input caps to short through the inductor and toast the lot.Might be lucky here. I'd clean it, remove any incidental shorts, check for further ones, scratch off the solder mask past the caps, solder on some bodge wires and bring it up slowly on a bench supply and see what happens.This is an image of a non exploded board apparently. Not a very good one unfortunately but best I can find:Worst case you learn something so

author: wraper
author_rank: Unknown
timestamp: June 29, 2018, 11:34:10 am
content: Quote from: bd139 on June 29, 2018, 09:58:08 amPower bricks do not have current capability to cause something like this. It would need to be something like ATX PSU as minimum. And even ATX PSU likely would just shut down by overcurrent protection.

author: bd139
author_rank: Super Contributor
timestamp: June 29, 2018, 11:49:19 am
content: The thing is rated at 60W max. (12V/5A) which is quite a lot. Possibly the output cap discharged instantly and relieved the low resistance components of their position of the board, then proceeded to leak under 60W across what was left. Power supply will quite happily deliver that into some tants for example if reversed. I know because I occasionally do thisEither that or car battery "hey lets run this portable redneck style".Hypothesising of course here.

author: wraper
author_rank: Unknown
timestamp: June 29, 2018, 12:09:22 pm
content: Quote from: bd139 on June 29, 2018, 11:49:19 amIt still would be not nearly enough to cause explosion like this. Output capacitance won't be more than 3000uF. Maybe enough to damage ferrite beads but not enough to explode them together with traces. Also don't forget that those ferrite beads were rated for at least 5A as well. PSU of such power is used for cases when something like external HDD is attached.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: June 29, 2018, 04:17:32 pm
content: Quote from: wraper on June 29, 2018, 12:09:22 pmDunno any case worth trying his luck in repair who knows might work

author: spoon
author_rank: Newbie
timestamp: June 30, 2018, 03:35:47 am
content: Thanks for the responses! I have a quick update and a new question:In an attempt to find the short, I fed some current into the board via my bench power supply. I eventually found that U4 (pic attached) was getting extremely hot. I'm assuming that's at least one of the faulty components. Problem is, it's only marking is "ACSG" which I cannot find anywhere online. I'm thinking maybe it's just a date code or something? Can anybody point me in the right direction on what this is and a potential replacement?Thanks again!

author: tsman
author_rank: Frequent Contributor
timestamp: June 30, 2018, 04:04:25 am
content: It is aMPS MP1495

author: wraper
author_rank: Unknown
timestamp: June 30, 2018, 08:12:40 am
content: Defore ordering DC/DC converter IC, try powering it's output with external PSU. You could also check it it's input-output is not shorted.

author: Rasz
author_rank: Super Contributor
timestamp: June 30, 2018, 09:29:42 am
content: it does look cracked

author: stj
author_rank: Super Contributor
timestamp: June 30, 2018, 10:22:05 am
content: it is cracked, i would also check the resistors around it against any example schematic in the datasheet.maybe also check the inductor if you have a suitable meter.

author: spoon
author_rank: Newbie
timestamp: July 01, 2018, 12:51:55 am
content: Thank you! I don't know how I would have figured that one out. I'll attempt to test it and the surrounding components.

author: wraper
author_rank: Unknown
timestamp: July 01, 2018, 09:10:49 am
content: Quote from: spoon on July 01, 2018, 12:51:55 amThere is no point testing surrounding components. What's important is to check if it's input/output is shorted and if what's powered from the output of DC/DC converter got fried as well.