RCD tripping fault help

[jakeevans]

Hi Everyone,

I hope someone can help, basically I have the Logitech Z906 Speaker System along with the Behringer 1204USB Mixer and one of these devices are causing my RCD at home to trip. They've been working together for about 3 years now, but all of a sudden this week, when I came to use the mixer/sound system, it's starting to trip. Being related to RCD I thought someone out there can point me in the right direction into which one it is?

It took me ages to narrow down but after disconnecting all but two of these devices I finally found that either one of them are creating a nightmare and keeps cutting of my power.

I turn on the speaker system, they turn on fine, I turn on the mixer, that turns on fine, I play some music, plays for a while then boom, RCD trips. So I keep trying different methods trying to find which one is causing the issue but it's doing my head in. 2nd Attempt - I turn the speakers on - fine. Then switch on the mixer, and boom, RCD trips. However, 3rd time round, mixer is on fine, speakers are on fine, then trips after a few minutes. I'm going round in circles which one it is.

My question is, has anyone had this issue before? The speakers are only about 3 years old, so is the mixer. Which one is causing the fault. Could the mixer now be faulty? or the speaker system? The speakers are connected to the mixer, could the speakers send some strange power down the audio cable and causing the mixer to short or something? I'm just so confused.

Kind Regards,
Jake

[Manc chippy]

Sounds like something is shorting. It happened in my house and I did continuity tests for hours until I found the problem. If you know how to do these things then get yourself a multimeter and just keep elimenating every wire until you find problem.
Otherwise call a spark.

[jakeevans]

Thanks for your reply Manc chippy for confirming it may be a short, It drove me nuts to narrow down it was one of these two items that were causing the tripping, I've now fully disconnected them, will have a look to see if I can test them or call out a spark.

Kind Regards,
Jake

[arco_iris]

Which RCD trips? The main one (usually on the left) or do you have individual ones (RCBOs) on each house circuit? You're definitely talking RCD & not an individual circuit trip? The equipment is extremely low powered (mixer 40 watts, speakers 23 watts) so a fault is quite likely to be elsewhere, and RCD trips are extremely sensitive these days.

If the equipments are plugged directly into a wall socket, (which could be faulty) have you tried either:

[a] Moving them to a different room and therefore, socket;
Using an extension lead to power them from a different room/socket.
[c] Plugging each item in to separate sockets, if necessary using extn. lead for one or other.

If they go through an extension lead, (which could be faulty) have you tried using a different lead?

Carefully inspected the power leads for damage?
Don't do this while the equipment is powered up though!

If they use conventional 3 pin plugs, have you checked the state of the wiring inside the plug? Looks like the mixer uses an IEC type computer lead, (these are usually sealed), have you tried a different one? Can you connect up (or borrow) different speakers other than the Z906 setup?

Is the equipment inside a conventional house, or a shed down the garden? In a loft with mice eating the cables?

[jakeevans]

Hi arco_iris,

Many thanks for your reply and trying to help me identify the issue.
Here is a picture of the fuse box, the one that that trips is the one on the far right (labelled R.C.D)



The individual ones don't go down (I thought usually the one affected (i.e. downstairs sockets) should go down but instead shuts power to all RCD circuits?)

The equipment is connected via extension leads, however, I have ruled out them out as I had changed them, and still the same fault.
I have also checked the 3 pin plugs, no sign of any damage, fuses inside look ok as well. I can't change the power lead for the speakers as those are hard wired in,
however, will try another IEC cable for the mixer (like you mentioned, it is sealed), but there is no signs of power lead damage on the outside, will report back once checked.

Equipment is in a conventional house, not in a shed or anything. I highly doubt it's mice, I've left the mixer+speakers unplugged and it hasn't tripped in the past 72 hours.
I did try again today just for re-assurance, plugged them both in, and straight away RCD trips.

I also do not know if is relevant, but I seem to be getting like a small tingle shock when I touch the mixer, not sure if that's giving the game away that it is 100% the mixer? or a short inside of it?
Another giveaway is that the speakers are on...but I remember last time I checked, I just went to switch on the mixer and straight away the RCD tripped so it's gearing me more to that itself.
I am also still curious whether it's the speakers though? Not sure if they are sending some sort of overvoltage signal that's going to the mixer and that's causing the issue?
I have tried disconnecting the cable from the speakers to the mixer, and remember that everything seemed ok for a while, unless it was a fluke.

I'm also going to do what you mentioned and take them to a completely different socket, maybe that can shed some light on the device that's causing it.
As I mentioned, they've been working in harmony for over 3 years, so I know it's probably nothing else other than one of these playing up.

Thanks in advance for your help and advice.

Kind Regards,
Jake

[Someone-Else]

The individual ones don't go down (I thought usually the one affected (i.e. downstairs sockets) should go down but instead shuts power to all RCD circuits?)

I see confusion / misunderstanding is arising. Allow me to explain.

The individual "switches" in your consumers unit, are Miniature Circuit Breakers. They are designed to operate in overload condition only.
The overload can be a variety of things. Too much connected, a short circuit. etc (These can then be broken down further)

A Residual Current Device detects any difference between Live and Neutral.
Imagine a pipe in a loop, water goes out one side and comes back the other.
If a hole is made in the pipe, water will now leak to earth, so what is coming back is not the same quantity as what went out.
An RCD will detect this difference and switch the whole supply off.

I also do not know if is relevant, but I seem to be getting like a small tingle shock when I touch the mixer,

The above is your answer. The mixer has a component that is starting to break down and is allowing a "Leak"

[jakeevans]

Hi someone-else,

Brilliant, thank you for the clarification and explaining that, it makes much more sense.
Now that I know the individual switches only go of in an overload situation, it's clearer why the RCD just trips.

I'm glad that you also agree it's the mixer, based on that tingle/shock, problem is it's just gone past its warranty period by 3 months I think
I'll get in contact with the manufacturer and see if it can possible be repaired or replaced.

Thanks in advance for your help as well!

Kind Regards,
Jake

[DIY_Johnny]

A Residual Current Device detects any difference between Live and Neutral.
Imagine a pipe in a loop, water goes out one side and comes back the other.
If a hole is made in the pipe, water will now leak to earth, so what is coming back is not the same quantity as what went out.
An RCD will detect this difference and switch the whole supply off.

so does a MCB just disconnect the LIVE only? I often wonder why cutting a wire with a MCB off for that circuit still cause the RCD to trip. By cutting the wire, is the short between the Earth to Neutral causing this? That is current from Neutral on another circuit now flowing to earth? Thus making me think an MCB only disconnects live?

[Someone-Else]

An MCB is only single pole, so when switched off, it only disconnects the Live.

There is often a slight imbalance between neutral and earth, and when you join the two together (Cutting the cable can join the earth to neutral) The RCD detects the imbalance and trips.

[jakeevans]

Hi Everyone,

Thanks so far for everyone's help, so I tried it with a different socket, both the speakers + mixer, and same thing, RCD tripped so I know 100% its one of these devices.

When I tried a power socket in a different room, here's what happened:
-Powered Behringer Mixer Only - RCD didn't trip
-Powered Z906 Speaker System Only - RCD didn't trip.
-Plugged in Laptop into Mixer with audio cable - RCD didn't Trip
-Plugged in Laptop into Speakers with audio cable - RCD didn't Trip
-Plugged in Mixer to Speakers with audio cable - RCD DID TRIP

-Changed audio cable - same thing happened.
So this led me to believe that the speakers or the mixer are sending probably some high current
between each other via an audio cable?

So I decided to just have a go with my "Non Contact AC Voltage Detector (90-1000v)" pen and I don't know if this normal or not, but the voltage pen is lighting up on the phono input cable on the speakers. When I connected this to my laptop, the pen lit up when I touched my laptop. When I disconnected it from the laptop, the pen only lit up on the cable.

So not being that electrically minded, my theory is, should there be that kind of voltage coming out from the speakers input ports?
God forbid this isn't a live voltage?

I connected the phono cable into the mixer only, and it didn't light up, so is the speakers sending high voltage out through the input ports. Possibly a fault in the speakers themselves?
I have heard Logitech are famous for having inbuilt transformers, and as the speakers are off most of the time, but the plug remains on, I heard this can reduce the lifetime of the transformer possibly causing this fault of some kind of leakage?

Kind Regards,
Jake

[Someone-Else]

So I decided to just have a go with my "Non Contact AC Voltage Detector (90-1000v)" pen and I don't know if this normal or not, but the voltage pen is lighting up on the phono input cable on the speakers.

I would suggest you buy one of These and put your "Non Contact AC Voltage Detector (90-1000v)" in it.

Before you do, rub it up and down (fast) on your sleeve, now do as above.

[jakeevans]

Hi someone-else,

Thanks for your reply.
Do you mean the non-contact version is rubbish?

Kind Regards

[Someone-Else]

Don't insult rubbish.

Seriously have you tried rubbing it up and down your sleeve yet?

[jakeevans]

Hi someone-else,

You've lost me? Are you being serious?

Anyhow, I've ruled out about the volt pen, tried another speaker input and its lighting up on there too...guest will wait for the electrician to arrive.

Kind Regards

[Someone-Else]

Hi someone-else,

You've lost me? Are you being serious?

Yes, i am being very serious.
Wear a nylon jumper or some other such man made fabric and rub your volt stick up and down (fast) on the sleeve, post here what happens (Its safe and interesting) you have to do it just out of curiosity, it also helps explain something