Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Need some advice with my 557 - sound gets muted.

Folks, I'd really appreciate some insight into this matter.

Yesterday, while listening to some music for about two hours, when trying to raise up the level a bit (to a really loud setting, but nowhere I haven't been before), my 557 quietly quit on me (sound muted gently, without clicks or noises). The front led started to slowly fade away. I cycled the power switch on the back off/on and all was back to normal.
Never happened before so I decided to test for a repeat.
I allowed for the system to cool down (the temperature of the fins was high, but then so it was usually). I restarted the system later, with all connections checked (but I did not at this time do any measurements on the speaker cables, frankly I didn't think there could be something wrong with them). After about two hours listening without problems at the voulme level I usually use, I decided to go up on the volume a bit. It did the same thing - quietly muted the sound. I cycled power down, then up, all got back to normal.

I stopped experimenting at this point - I do intend to look a bit more deeply into this but I could certainly use some advice on this topic.

The manual says the 557 will mute when overheated - doesn't seem to me like it's hotter than usual when it mutes. Also, there is a mention of a DC protection that will kick in when overload is detected. Again, the volume setting when this occured was one i frequently used on the same music material many times before without a glitch.

Does anyone know how to tell if it's the thermal or the overload protection that kicks in?
Any advice on what to do under the circumstances?

Thanks in advance,
Dorian

Uh ... did anyone run into this kind of problem before ?

Dorian,
Sorry...sounds like a call to M is required.

10x Nick. Thought so.
Yep. Called my dealer - I will return the equipment today or tomorrow. I wonder how long it will take to get it fixed ...

Ok, by the looks of it, I'm about a hair split from DS. I have sent my 557 back to my M dealer last tuesday. His conclusion until now is that there's nothing wrong with the amp ..
Presumably I should be glad, but I'm actually freaking out, I know perfectly well what has been going on at home last monday - and although I wouldn't call the symptoms systematic - they gave me the certainty that they would be easily reproduced at the dealer's.

The one thing he says he didn't do is test it feeding signal via the balanced inputs (as I use it regularly). He'd presumably be trying that right now ...

So, let me put things a little bit into perspective:

M is VERY far away ... (and the dealer is not exactly around the corner either, but that I can manage)

557 started acting up about 10 days ago: it shuts itself down whenever it feels like it, looks like the overload protection kicks in [the sound will be muted without any additional noise and the frontal green led will slowly fade out; the situation can be reverted to normal by cycling the power switch on the back off/on].
It does this irrespective of temperature, and in testing it did so not only at high volumes (most of the times it would cut out when I reach 73-74 on the controller - otherwise levels I used frequently in the past - but it also went down on me after about 35 mins of listening at 65, and then at 62 ...) but at normal ones and also two times with the system idle (CD player, Controller and amp on - NOT in standby, but on, no music playing).
Measured with a DMM the speakers' impedance and checked for cable shorts on the speaker cables. All looks OK.

In the heat of the moment I did not check if it switches itself off when disconnected from other stuff (and I kick myself for not having done so ).

System is: G08 - 502 - 557 - Dynaudio Contours 3.4
all interconects balanced - Audioquest Jaguar
Audioquest Bedrock speaker cables.

No power conditioning, just a voltage regulation/surge protection for the player and controller and a surge protection for the amp.
All protections did not indicate overvoltage or spikes at the moment of testing. Electrical installation includes differential and surge protections, nothing went wrong, other (rather numerous) equipmenta were working just fine. Also tried to power the 557 amp from a different outlet, this time directly from the outlet. Same thing happened

There's a few things I wish I did, but now the amp is with the dealer, some 160 miles away , and if he says it's ok on balanced inputs I'm afraid the next step will be to send the 502 in to see if it outputs some [censored] stuff (although I doubt that). Then I might have to ship over the whole system - at least it's all bought from the same source ...

Too bad for me - I really like the gear and miss it and by the looks of it it's not going to be fixed soon

Ok, so, if you have some ideeas, this is the moment when I'd really need some help with it ...

Should I call M (what phone number should I use - or can anyone give me a contact?) ?
Alternately I could e-mail, but somehow I don't trust e-mail to generate a quick response - in case I need to do it, which address should I use?

Any help would be greatly appreciated.
Cheers,
Dorian

You could have a faulty load (like a shorted Tweeter).

Try playing with the loads.

Try 1 Speaker on both channels.

Then try the other speaker on both channels.

You will prob find it's 1 channel or 1 speaker which will clearly identify the culprit.

If not call M directly.

Thank You George, I can tell you that when it works it all sounds normal on both channels, although I did not try to testthe channels and speakers separately. Now I cannot test, the amp is at the dealer's

News is that my dealer informed me the problem is reproductible when connecting a controller via balanced interconnects to the 557. Seems like connecting the balanced inputs causes the behaviour ?!? While on the unbalanced inputs it workd fine ?!?
I will call M in the UK and try to talk to someone there about this.

I have a similar problem with my 557. It shuts itself down about once a day on average. But sometimes it can go a week without shutting down.

I leave it switched on permanently. Most of the shutdowns have been while it's not being used. I think it might be the protective circuitry incorrectly kicking in when there's a glitch on the mains. I switch it back on and it's fine for another 24 hours or so. Just a minor inconvenience, but I'd much rather it didn't do this.

Dorian,

re E-mail, M I've found M extremely good at responding - Dave.Hall@Meridian.co.uk is a VERY helpful guy in support...

Good luck

George C.

Thanks guys, I'm supposed to have it back in a week or so and get an explanation about what went wrong (looks like it's actually a problem with the balanced input circuitry which results in DC detection and the protection kicks in).

Surinder, I guess you'd better try and contact M - the problem might manifest itself with increasing frequency in the near future

Will drop a note if I get some useful info on what actually went wrong and why.

Cheers,
Dorian

Interestingly enough, I'm still waiting ...

I think there has been a backlog at Meridian. My G98/68 went off for a 'service' and it was mentioned that they hoped to turn around G series bits in about 3 weeks. I got it back last Friday and it was away about 6 weeks although I expect it spent some time on the bench being soak tested. The reason for my service was self inflicted so I can't complain.