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[digitalnemesis]

Is my Zyxel VMG8924-B10A faulty because it rebooted automatically twice this week 5 days apart for no apparent reason.


How can I check what is causing the automatic reboots? All remote management is off and it's unbranded so could it be the power supply not giving enough power or the stats overloading it?


Currently on 28-jumbo-tel-x6-stats1.1-cmd

[broadstairs]

The PSU can be troublesome with this router as it needs quite a lot of power, you need to check it is the correct PSU it's not the same as the 8324.

Stuart

[digitalnemesis]

Hi this is the power adapter that came with mine:

[broadstairs]

I seem to remember 2A output is correct, I'll try to dig mine out and check later. If I'm right it is possible you have a duff PSU but there's no easy way to check as you need to test it under load.

Stuart

[Alex Atkin UK]

I seem to remember 2A output is correct, I'll try to dig mine out and check later. If I'm right it is possible you have a duff PSU but there's no easy way to check as you need to test it under load.

Stuart

Even under load it can be ripple issues that you wont see without a scope.

[banger]

My VMG-1312-B10A rebooted unexpectedly tonight as I was listening to a stream. It has been up for ages before in bridge mode but this is the first time I have used it in router mode.

[Weaver]

None of my many ( > 4 ) VMG 1312-B10As has ever rebooted itself, all in modem mode, never tried full router mode. I use our very own Johnson’s firmware (feb 2020 version) - binaries ready-built and sources. Firmware for ZyXEL models available there too.

I agree that a weak power supply brick could well be the problem. One with a higher current rating is a very good thing, but the ZyXEL-supplied brick is fine. Otherwise bad firmware or a defective unit. A short-term current-draw spike can cause a very short D.C. rail down-going spike that isn’t easy to see with a scope unless you ‘zoom in’.

Too much inductance inside the device, in the line going into its guts would mean that when there is a fast current draw demand, the required current isn’t delivered on time, so the unit dies because the voltage drops fast. The required current can (eventually) be delivered, but always too late; it doesn’t rise quickly enough. I have seen this problem with prototype computers at work. So internal resistance and inductance are the two ills.

Burakkucat uses a VMG 1312-B10A in router mode iirc so he will know about reliability.

[burakkucat]

Burakkucat uses a VMG 1312-B10A in router mode iirc so he will know about reliability.

My one and only problem occurred a couple of months ago when the switch-mode power supply just died. In the preceding fortnight I experienced two unexplained system re-boot events. On both occasions I was quick enough to see the "all LEDs out" state followed by the usual LED sequence of a system power-on. However, as Weaver has mentioned, I use a VMG1312-B10A and not a VMG8924-B10A.

Perhaps the PSU is "giving hints" that its demise is near? Who knows . . . 

[banger]

I have swapped out my VMG-1312-B10A and adapter. Whilst at an idle moment I tested the adapter of the rebooting router and it was around 14.2v with a multimeter. This seems about right?

[Weaver]

That’s about right. But as for voltage downward-going spikes, a scope would be needed to catch those as they will be of extremely short duration.

[digitalnemesis]

Hmmm yeah I probably think there's something obtuse occuring with my adapter. I recall noticing something iffy going on with my VOIP adapter when the power supply was on its last legs. I'm not sure how to prove this though without the proper equipment.


Could there be something faulty with the hardware of the router itself though?

[Weaver]

Not likely, but what do I know. Capacitors deteriorate for example. I would just swap out the power supply first for a good one with a strong current rating, as that’s a cheap fix. Depends on what your time is worth to you, but a £10-15 PSU from ebay is so cheap your time diagnosing it would be costly, especially if you need to buy a scope to do it.

I have a mountain of VMG 1312-B10As but I don’t know if all the PSUs are the same for the different models.

[tubaman]

This works fine - https://www.ebay.co.uk/itm/Genuine-BT-Home-Hub-5-Type-B-Power-supply-12V-2A-WILL-NOT-WORK-WITH-TYPE-A/174441136397?epid=1891896714&hash=item289d80810d:g:oJQAAOSwsnldD8P1 - it's what my 8924 has been running happily on for a few years now (must be 'Type B').
 

[Weaver]

Would Tubaman’s ebay PSU work with a VMG 1312-B10A too? I’m wondering if the power supply requirements are the same across the range? And if they’re not then it’s just a matter of getting a superior unit, provided the connectors and polarity are the same.

[burakkucat]

Would Tubaman’s ebay PSU work with a VMG 1312-B10A too?

Yes, it would. I have one, which is kept with my reserve VMG1312-B10A, for a just-in-case event.

See: Now What?