How to break a Uniti 2 (and other streamers?) with a LAN cable

Sooo - yesterday I received a new TV which I proceeded to setup in the way I thought was correct i.e. connect all cables before plugging the TV into the mains

Unfortunately I hadn’t realised that I should also have turned off the LAN router which was connected to the cable I went to plug into the new TV.

Outcome was a large spark between the LAN connector and the TV LAN socket, accompanied by a loud buzzing from the Uniti 2 - which wasn’t connected to the TV in any way other than sharing the same Netgear Router for their LAN connection.

The Uniti now has no volume control, and plays at a fixed volume with accompanying crackles. Attempts to control the volume are met with a clicking noise and no other changes.

The TV appears to be fine but I’d love to know what happened so that I can avoid making the same mistake when the Uniti returns from its spiritual home in due course. I have been plugging live LAN cables in and out of kit for years and this has never happened. My working hypothesis is an earth problem due to the TV not being plugged in.

Was anything else connected to the TV at the time. If not then i’d suggest it sounds like it was due to static discharge rather than anything else as the TV wasn’t plugged into the mains, the TV building up a charge whilst you were unpacking it. Was the Ethernet cable that you were connecting to the TV shielded ?

You say the Uniti is behaving strangely but has it been powered off and restarted since this incident ?

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Hi Jamie

The only other thing that was connected was the aerial - which does come from a booster amplifier. The size of the discharge was far larger and longer than static though. I don’t believe the cable is shielded but I don’t know for sure.

I’ve spoken to Naim Tech people and done everything that could be done but the volume cannot be controlled any more and there is a background crackling to anything playing. I even factory reset it and left it off overnight to ensure complete discharge of any capacitors.

I’m resigned to it needing repair and a service but just concerned about what I can check to ensure I don’t just repeat the trick when the new unit comes back

Thanks for the response!

Ah ok - that makes more sense then. You’ll find the antenna amp will have no earth connection and you’ve introduced one via the TV chassis and Ethernet cable shield and this has found its way via the Uniti2 to Earth. You can check if the cable is shielded by looking at the connectors (it will be metalised plastic or metal rather than just clear plastic). Normally there should be no issues plugging and unplugging Ethernet cables - the design of the NIC means they are galvanically isolated on the data connections, but when you introduce a shield into the mix then you have a connection which can carry (mostly harmless) leakage currents from different equipment via the shield.

Out of interest is it a single booster amp or a distribution type amp with a few TV’s connected to it ?

Hope you can get the Uniti fixed soon and i’d avoid shielded Ethernet cables in future.

Hi James

That makes sense now - and not a conclusion I’d have got to on my own…

It is a distribution type amp with 5 TV’s on it

I’m hoping it can be fixed soon too. Just waiting for info on how to do this…

Thank you for all your help on this - much appreciated!

Hmm - I’m still surprised this happened to your Uniti - just one more question, what setting is the signal ground switch set to ?

It’s set to chassis - which fits with what you are saying I guess

Ok just wondering - I’ll be interested in what Naim find as i’m curious as to the failure mechanism. I wonder if @NeilS has seen this sort of issue before with these products ?

On an unrelated note, i recognise Penarth pier in your profile picture. We used to take our school racing hovercraft down onto the beach there next to the pier to practice. Happy days.

I’ve got to be honest, it was a complete surprise to me too. I’m still concerned there is something leaking to earth somewhere for this to happen. I’ve just looked at the LAN cable into the TV and it is plastic, but the surround of the LAN socket on the TV is metallic, so one of the contacts in the LAN cable must have arced to this surround. I think that has exhausted my knowledge of what else might be going on…

I’ve been in Penarth for most of my life so probably saw you down there at some stage. Were you there when the multistorey car park was next to the pier slipway?

If they are not shielded then I’m a bit surprised as to why this happened…very strange.

The car park was still there - we would have been down there in the mid 80s. Not been back for a fair while so a lot has changed.

Hi PB,

An interesting one, if the 5 TVs are class 2 devices (no mains earth connection) there is an allowable amount of leakage to the chassis through filter capacitors in the power supplies. These TVs would have their chassis all married up via the coax outer screens. This accumulated leakage could in theory then raise the chassis potential of your new set while you are making the other connections.
This is why larger aerial distribution systems (in blocks of flats for example) are earthed to protect against the leakage rising to dangerous levels, particularly if a tenant’s TV should develop a fault.
Not really necessary in a domestic environment, as the leakage current is very low. If you didn’t “feel” anything tingly when you held the aerial plug, I shouldn’t think you have a TV fault.

As to how this could have damaged your Uniti via the Ethernet cable, I’m not sure.
The fault condition you describe is a known one, usually caused by damage to the bipolar power supplies to the volume IC. We have seen a few examples of it, but the cause is unknown - perhaps this is it?!
I’ll have a look over the circuit diagrams when I get a minute & see if I can come up with any ideas.


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Hi Neil

Thanks for getting back to me with a possible explanation for this. I’ll be interested to see what you find when you look at the circuits.

It would be interesting if you could also look at what might have happened if the aerial was not plugged in. I’ve just been discussing the order of things yesterday with my son, and we can’t remember if the aerial was connected at the time we tried to plug the LAN cable in. This would then mean that it is something within the brand new TV discharging on first contact with an earth. I can only think of a capacitor or a massive static discharge as suggested by Jamie earlier in the thread.

Whatever it is I’m unsure what should be connected to the TV first to enable a safe discharge. For the Uniti I guess I should ensure the grounding is set to isolated when I get it back? Just checked and, even though the LAN cable from the router to the TV was unshielded, the LAN cable from the router to the Uniti WAS shielded. I’ll get this changed so there isn’t a route to earth through this direction.

I’m hoping Naim will get back to my dealer soon with a date for the unit to come in but not sure on waiting times for repairs at present. I hadn’t realised how much I depended on the Uniti 2 until it’s been taken away from me… :unamused:

It can be difficult sometimes to establish a clear chain of events when something like this happens!
I’d rule out any charge coming from a capacitor in the TV - that would potentially be dangerous. A static build up on the set from the packaging is not out of the question, although I usually find that discharges through me - ouch!
Which dealer will it be coming via? I’ll keep my eye out for your Uniti in due course.
Also, what model is your Netgear router & did you have any other connections to the Uniti at the time (other than speakers)?


Hi Neil

You are correct about the chain of events as it’s not something you are expecting at the time. I know that the LAN cable hadn’t actually touched the TV before it started sparking. This went on for a good second before my brain kicked into gear to move the cable away from the TV as I was trying to process the unexpected noise suddenly coming from the stereo at the same time.

You’re probably right about it not being a capacitor, so this just leaves static, which I guess could be possible as we’re just holding plastic and glass when putting the TV in place but it still doesn’t seem correct. So that implies it coming from the Netgear Router to the TV, but why and why not since? Perhaps a loose connection when pulling the cable to the TV? I’ll check that too.

The only other thing plugged in at the time is an external FM aerial which comes through the same route as the TV signal before being split at the wall socket.

The unit is coming in from Audio T in Cardiff. It’s a 2014 model. The Netgear Router is a GS 308.
As it’s now around 6 years old I’ve asked my dealer to get it serviced too and to have the dim screen replaced as part of it going back. I know it’s not as up-to-date as the latest kit but it’s perfect for my needs so want to get it back up to spec if it has to go in anyway. Please be nice to it if you do get to see it :slightly_smiling_face:

To be honest as described this sounds like there was a fault with your router switch port or TV Ethernet port.
For safety reasons compliant Ethernet sockets have to be galvanically isolated to prevent precisely this from happening. It sounds like this was not the case which allowed the spark to cause damage. Compliant Ethernet sockets are isolated to 1.5kV DC for a short period of time. It is possible but unlikely the static discharge was greater than 1.5kV, as that could be potentially lethal.

Just one other consideration are your Ethernet leads regular ones (that is UTP), or are they earthed (STP/FTP/ScTP) - the construction type should be labelled on the Ethernet lead jacket ? Possibly there was a floating earth discharge via the earthing on the cable, but again any floating earth device to be compliant with EC mark should not allow this to happen to the point where this is damaging static spark. If you have floating earth network devices DO NOT use earthed Ethernet cables.

Thanks for the response SiS

It was a pretty hefty spark when it happened…

I’m coming to the conclusion that in connecting the LAN cable to the TV I’ve pulled the router around and caused something to short or disconnect slightly. The router still works well and the TV internet has been rock solid since the incident. I’ve put the LAN cable in and out of the TV a couple of times now and all seems to be working as I’d expect.

I have a mixture of earthed LAN cables (to the Naim which was switched to ground to the chassis) and unearthed (to the TV). To be honest I’ve never really taken much notice of whether they were shielded or unshielded until now - being more interested in the CAT type and whether they were the right length for the job in hand.

I’m probably going to swap out all the earthed LAN cables I have for unearthed whilst the Uniti is repaired just to be safe. I’ll have a nose around the forum for the pros and cons of shielded vs unshielded LAN cables generally just to try and understand them better first.

Hi PB,

Had a look over the circuit diagrams today - still none the wiser as to how the “event” could have caused the fault condition.
Will have to assess the unit when it arrives & take it from there I think.


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Cheers Neil

So it remains a mystery. Hopefully you might be able to find something when it comes in.

Still waiting to hear from Naim when they want the unit in so I guess it might be a while yet. Have you got much of a backlog in the Service Department?

It’s a manageable amount on site, but I believe there are more in our distribution warehouse that were probably in transit when the site closed.
Give Henry in tech support a nudge, he will have a better idea of the current RMA situation. Understandably we are also experiencing delays with some of our component supplies too.


Thanks for the heads-up. I won’t contact Henry as he’s probably got enough to do as it is. I’m sure you have a decent queuing system set up so I’ll just have to wait my turn.

I hope the return to work is going well and everyone has come through OK so far :+1:

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