Z-5500 not working

[Varunnagwekar]

I purchased Logitech's Z5500 speakers a few months ago from a local retailer. But a few days back it has suddenly stopped working. The entire unit is not turning on no matter what I do. There is absolutely no light showing anywhere. I have checked all the connections, all the power connections and all the settings. Hence I have come to the conclusion that it is a hardware based problem.
Does anybody have any idea what might the problem be and how I could get it repaired. Its still in warranty. Should I get it repaired by a local person or should I get it repaired by the service center itself.
Also, does one have any contact details and location of the service center of Logitech?

I will be really very grateful for any help provided. Thank you.

 

[The Sorcerer]

Did you change the fuse? Which surge protector are you using for it?? I have seen a lot of z-5500 dying for God knows what reason. Its a pretty over-expensive and over hyped speakers so just see how it goes...

 

[pimpom]

Like The Sorcerer said, it could be just the fuse, especially if there really are many cases of Z-5500s dying. Maybe, in trying to make sure the unit is protected, Logitech uses a fuse that's rated too low and blows too easily. Estimating the proper fuse rating for an electronic equipment is a complex business and most of the time it's impossible to do a precise calculation.

I'm not up-close familiar with the Z-5500. Is there a fuse holder accessible from the back of the box? If not, the fuse must be inside. However, there is probably also a thermal fuse integrated in the power supply transformer. If this fuse is the one that keeps blowing, replacing it is a bit more involved than the normal glass fuse.

 

[The Sorcerer]

As far as I have heard from previous dead z5500 users that the fuse that is used in z5500 are ceramic slow blow fuse T2AH250V. The problem could be either the fuse (I hope- for your sake) or the transformer on the circuit board (I dont hope although it can be taken care by the local techs if the warranty has been voided as per company standards).

 

[Varunnagwekar]

So, should I take the sub-woofer to the service center or the whole equipment (along with the speakers)?

 

[pimpom]

It's just as I suspected. It's a 2-ampere fuse and that's way too low for a 505-watt amplifier. That is, if the amp can actually pump out 505 watts continuously (amplifier output rating is one of the most abused technical specifications).

A true 505W analog (not PWM) amplifier will consume at least 750W from the mains at max output. That's more than 3 amperes at 230V. Power-on surges can easily exceed that. A slow-blow fuse can cope more easily with momentary surges, but 2A is still too low and cannot cope with the amplifier's normal load current even without the power-on surge.

My guess is that the amplifier's audio output stages cannot stand continuously pumping out their max rated power without overheating (That's a sign of bad design and commercial hype), and that Logitech expects the user to drive the amps to high power levels for only brief peaks of milliseconds. So they put in a low-rated fuse to blow in case the owner tries to drive it at high average volume levels. In short, they're playing a dirty trick.

 

[anubisX]

It's the fuse. It's a very common problem with the Z5500. At the back of the sub-woofer, there is a fuse, just turn the fuse holder with a coin and take it out. Replace the fuse with a 3 AMP (time delay) fuse and it should be fine. It'll cost you Rs. 3-4 and it won't void your warranty. The same thing happened to me and the Logitech guy told me to do so. If you want to use 2 AMP instead of 3 AMP, then buy atleast 10 fuses as you'll need them soon. Power surge blows Z5500's balls off

 

[The Sorcerer]

It's just as I suspected. It's a 2-ampere fuse and that's way too low for a 505-watt amplifier.

Well technically its not a 505w amplifier- if that was the case you would have got the bill fit for a mid range gaming pc. And besides the power consumption is not constant.

 

[pimpom]

Well technically its not a 505w amplifier-

I'm afraid I have to disagree. This is what Logitech says on their site:

Technical Specifications
Total FTC power: 505 watts RMS
Sub-woofer: 188 watts RMS (into 8 ohms, @ 100Hz, @ 10% THD)
Satellites:
Left/Right: 62 watts RMS x 2 (into 8 ohms, @ 1khz, @ 10% THD)
Center: 69 watts RMS (into 8 ohms, @ 1kHz, @ 10% THD)
Rear Left & Right: 62 watts RMS x 2 (into 8 ohms, @ 1kHz, @ 10% THD)

They even cite the power in RMS, not the misleading PMPO often used by many manufacturers.

if that was the case you would have got the bill fit for a mid range gaming pc.

How do you know that users of high-power amplifiers do not face a significant increase in their electricity bill because of the amp? They do. But the amount of increase depends on how regularly they play at high volume levels.

And besides the power consumption is not constant

Of course. Anyone with in-depth knowledge of how linear (analog) audio amplifiers work knows that. See my comment in the previous para. The power consumption of the Z-5500 is probably around 50W or less at idle and progressively higher in use depending on the volume level.

At full power, the consumption is even more than 505W because analog amplifiers have a substantial loss. The theoretical maximum efficiency of the usual Class AB amplifier is 78.5%, but practical designs have efficiencies of 55-65%. So the power consumption of a 500W amp at full power is 750-900W (in round numbers). This means that 250-400W has to be dissipated as heat and that requires active cooling or a HUGE heatsink.

My guess is that Logitech probably does not provide enough cooling (I have not examined the design of a Z-5500 in detail). That's probably why they use a low-rated fuse to blow in case the owner tries to use it at high power except for very brief peaks.

 

[The Sorcerer]

Well this wouldnt be the first time companies over exaggerating specs. But more power consumption doesnt mean better sound.

 

[anubisX]

What happened to the OP ? Did he replace the fuse ? Oiiiiiiiiiii !!! Update the situation..

 

[pimpom]

Yeah. It's always a good idea to report how things turn out. Not only for the satisfaction of those who tried to help, but also for background knowledge of everyone who reads the thread.

 

[anubisX]

^^ ditto that...

 

[Varunnagwekar]

Err...sorry guys for not reporting earlier. I do not have a net connection at home and could only report back once I got back to work. So, I am very, very sorry for that.

First I'll like to thank everybody over here for helping me out. I really appreciate it from the bottom of my heart. (Seriously!)

So, here are the details.

I've managed to successfully repair my Z-5500. The problem actually was the fuse (as accurately indicated by you guys). All I had to do was change the fuse. I thought that to change the fuse I needed to open the Sub-woofer. But all I had to do was open a small knob which housed the fuse on the outside of the sub woofer itself. This is relatively very simple, and can be opened by a small coin after which the fuse can be changed very easily. For this, I would like to thank Anubis X for giving me specific detailed instructions regarding this. All the while, I thought that the fuse was somewhere inside the woofer. And opening it would be very hard plus would void the warranty. And even after knowing what the problem was, I would have foolishly gone to the service center.

Had it not been AnubisX and you guy's help, I would had been forced to take the huge woofer to the service center, the nearest of which was at vikhroli. It has really saved me a lot of time, effort and money.

Therefore I hope that other guys who own this excellent piece of hardware can solve this problem if they face it in the future.

Another very interesting thing happened after that. After the speakers were repaired, some new functions appeared on the control panel like Stereo1, Stereo2 and Stereo3 which were not there before. Also, the 6-channel audio which was there before has now disappeared now. I have a sound card attached to my pc, (I think it's sound blaster). So, if you guys know anything about this please, I hope you can enlighten me.

 

[The Sorcerer]

Out of curiosity what kind of fuse did you use?

 

[anubisX]

The new features Stereo 1, Stereo 2, Stereo 3 appeared as you've changed the 6-Channel Direct to 1-3 Stereo from the back of the Control Pod. Change it to 6-Channel Direct to get back your old features Check the back of the Control Pod, you'll see a small switch that can go up and down, up is 6-Channel Direct and down is 1-3 Stereo. Keep updating !!!


What fuse did you use btw ?

 

[confused]

had the same problem, solved using same solution.....

 

[Varunnagwekar]

Actually I had missed a small trivial part of the repairing process which turned out to be a very dangerous part. I had an electrician coming over to my home that morning to help set up wires and connections for our new AC. I had asked him whether he knew about that particular fuse, he said yes. Then he took a wire (copper i think) and rolled it around the fuse and inserted it in the knob. It turns out that this was a wrong procedure as I was told by my friend. If in case of another electric surcharge the whole equipment would blow up because the fuse is not in a working condition to help in that case.
I will now buy a new fuse and insert that as soon as I get time. So, I'll update you on that in a few days.

Thanks

 

[anubisX]

Don't try this kinda things. Aare yaar, one fuse will be like Rs. 2-4, so why are you taking unnecessary risks ?

 

[pimpom]

Glad you found out about the danger of using just any wire as a fuse.

However, in an emergency, copper wire can be used IF you know the fusing current of the wire. For example, with common twin flexible wire, a single strand is often (but not always) of No.42 SWG size. This is equivalent to a 3A fuse and can be safely used as a 3A fuse. No.36 melts at 7A and so on.

In fact, the wire in a glass fuse is nothing more than a copper wire of the correct size for the rated current. Slow-blow fuses have a blob of metal, usually solder, on the wire. Due to the thermal mass of the solder, it takes longer for the rest of the wire to reach melting point. Therefore the fuse can withstand momentary overloads without blowing, but blows after some time with a sustained overload.