Much like the fault reported here: Zyxel NR7101 stopped working
My Zyxel NR7101 has suddenly failed. No lights, no LAN connectivity.
I've tried a new POE adapter and LAN cable. No Luck.
My issue is I'm out of warranty so not getting a return like in the linked post. Can anyone direct me to the PSU on the router so I can buy and solder a replacement in to test if that fixes it?
Thanks in advance.
Ah I'm so sorry to read this. Yes mine just went completely dead.
Ever since I got mine replaced under the RMA procedure all has been fine.
You say you are out of warranty. By how long? Could it be worth still trying on the basis that you understand there may have been a batch of devices with a faulty PoE supplies and that you might have been unlucky enough to have acquired such a device (albeit it did not fail within the warranty period).
At least UK consumer legislation has some notions about 'fit for purpose' and the like, and such provisions can sometimes be relied upon beyond any warranty period. Could there be an equivalent provision in your country?
Otherwise, I hope @bmork can help you here. Perhaps it would be fairly simple to replace the PoE supply in the device. And even such knowledge could come in handy for the future or for others.
Thank you. I'm in the UK. I did try the Zyxel UK support but they declined to help given it was out of warranty. I'll speak with them again and mention this particular issue to see if anything comes from it.
Sorry. This is way out of my league.
I guess someone knowing how to debug power supply circuits could fix it by locating and replacing faulty components. If it is a power problem. We don't really know, do we?
Maybe try connecting a 12V supply and see if that works? Would indicate that the issue is in the PoE circuit. There's a labelled place in the board for a 12V barrel connector.
Please keep us posted how you get on @Pioneer.
Wow nice link!
@Pioneer what’s the latest?
Ok so powering on with 12v gives me a flashing led down by SIM cards. However the ttl gives no response and nor does trying to access 192.168.1.1 on LAN. I’ve (me and ChatGPT) decided something is off in the dc-dc conversion. 48v gets into the conversion circuit.
I’ve taken the shield off to get inside because it was getting hot. Seems a large transformer (UMEC) is the issue with heat, whether it's 'too' hot I'm unsure.
Not sure where to go next though. I've ordered a barrel connector so I can keep 12V consistent, rather than trying to hold wires in place on the solder pads.
Sorry to butt in here, but is that list publicly available somewhere? I don't own a NR7101 myself, but am involved with a project that does use it. Would be good to know if I need to keep an eye out.
I too would love a list of affected serial numbers.
I’ve fitted the 12v barrel. That works and the router powers up fine. (So was just not waiting long enough when I was holding cables onto the solder pads).
So good news, the router works and definitely the 48v to 12v poe on the router is the issue.
My setup has this mounted outside so the Poe is ideal. Running a new 12v line wouldn’t be as neat or easy.Going to continue to see if I can find faulty components.
I’ve isolated it to one of a few components on the 12vdc rectification circuit. Something is causing a short to ground (I’ll upload a photo when I’m back at my computer, doesn’t seem to work from my phone).
Trouble is they’re all so tiny that I don’t want to start guessing and desoldering. Too tricky to handle.
Point it out on your photo ?
Bit more of an update. I made an educated guess at Q1 being the problem. (Top right - 3 legs).
I’ve removed it and it’s stopped the ground fault. The transformer no longer overheats (UMEC). And then I was able to continuity test the mosfet Q1 and it seems shorted. Also it’s one of the components that has the heatsink on the reverse side. So all seems to point to it being the problem.
Ordered a (hopefully) similar replacement (hard to tell as there isn’t much in the way of marking on it). Will fit it when it arrives this week and update.
Wow thanks a lot for the updates and massive kudos to you for working through this. Does the idea that this issue only affects a set of devices fit with what you have seen?
Absolutely astounding!
Do you suppose only some units are affected? Certainly my replacement has been going strong ever since I got it.
In theory all units could be a ticking time bomb?
Please could you elaborate? I’m struggling to piece this together in my mind from the photos.
