Anyone good with electronics?

Lethal` · 8 Dec 2010 at 14:05

I've got a Logitech X-540 speaker system, the subwoofer does not make a sound until the bass control is turned to about 3/4 of a whole rotation. Obviously this is faulty. I'm thinking its just a problem with the electrics in the wired remote. I realise this is pretty vague, but could anyone suggest how this might be fixed?

(this thread might be better in Sound City, not sure)

wildman · 8 Dec 2010 at 15:12

dodgy bass pot maybe, might need cleaning or have bad contact, possibly dry joints ? not sure just thinking of some of the basic issues that maybe relevant

Gamefreak501 · 8 Dec 2010 at 16:16

As above really - I reckon the bass volume pot is dodgy, if you're good with a soldering iron and can find one on eBay for example, you should be able to replace this, taking into account Electrical Safety.

Lethal` · 8 Dec 2010 at 16:40

Is this in the wired remote?

Beans on toast Dave · 8 Dec 2010 at 16:48

Contact logitech. I am sure they will replace the set

Lethal` · 8 Dec 2010 at 18:24

challengedavid said:
Contact logitech. I am sure they will replace the set

They have, with the new Z506. I think I prefer the X540 though, and it seems like a waste to just bin the lot when it could be a simple fix.

russ0r · 8 Dec 2010 at 19:50

Lethal` said:
Is this in the wired remote?

Yes. It's a potentiometer that is attached to the volume knob and increases/decreases the bass volume.
They're pretty cheap and easy to replace if you're handy with a soldering iron. Or it might just need a clean as suggested above.

Lethal` · 8 Dec 2010 at 19:57

russ0r said:
Yes. It's a potentiometer that is attached to the volume knob and increases/decreases the bass volume.
They're pretty cheap and easy to replace if you're handy with a soldering iron. Or it might just need a clean as suggested above.

Thank you for the info. I think I'll take it apart and experiment when I'm back home next week.

2bit · 8 Dec 2010 at 20:25

I doubt that it's the pot.
More likely to be a fault with the filter circuit.

Does the bass crackle as you twist the knob?

Lethal` · 8 Dec 2010 at 20:33

Nope, there is absolutely no sound or movement at all from the subwoofer until the dial is turned to 3/4.

2bit · 8 Dec 2010 at 20:38

Ah ok - I don't think it's the pot then. Sorry as that would have been a nice simple fix - I hate binning equipment without good reason too.

Lethal` · 8 Dec 2010 at 21:03

2bit said:
Ah ok - I don't think it's the pot then. Sorry as that would have been a nice simple fix - I hate binning equipment without good reason too.

What's it likely to be if it isn't the pot?

2bit · 8 Dec 2010 at 21:06

Hmm I'm not sure about these speakers without digging around more. Is the bass missing from both speakers - just to clarify?

Lethal` · 8 Dec 2010 at 21:09

2bit said:
Hmm I'm not sure about these speakers without digging around more. Is the bass missing from both speakers - just to clarify?

They're 5.1 speakers, bass isn't present until bass control is turned to 3/4 of the way.

2bit · 8 Dec 2010 at 21:44

Sorry - I've tried to find a schematic of the remote/amp in your speaker system and failed. I'm guessing the bass pot in the remote is a standard variable resistor type. If it only starts operating above a certain point then that indicated that the filter / crossover in the amp (the large unit) is at fault - not the pot. Modern potentiometers are generally very reliable and don't have an 'all or nothing' characteristic as you describe.

More likely to my mind is a fault with the filter circuit in the amplifier. I can't be more specific - but as I say I can't find an on-line diagram.

Makhaira · 8 Dec 2010 at 23:20

It's possible there's a break in the pot track which would produce the behaviour you describe. Since you're talking in the region of £0.50 - £1.50 to get a suitable pot, you may as well give it a go as a fix, you don't have a whole lot to lose!

Lethal` · 8 Dec 2010 at 23:42

Makhaira said:
It's possible there's a break in the pot track which would produce the behaviour you describe. Since you're talking in the region of £0.50 - £1.50 to get a suitable pot, you may as well give it a go as a fix, you don't have a whole lot to lose!

Yep sounds like a good idea, looks like I'm going to damage the wired remote casing opening it though. Pretty well sealed and no screws.

2bit · 8 Dec 2010 at 23:48

Makhaira said:
It's possible there's a break in the pot track which would produce the behaviour you describe. Since you're talking in the region of £0.50 - £1.50 to get a suitable pot, you may as well give it a go as a fix, you don't have a whole lot to lose!

True.

However it's really unlikely that the knob is connected as a variable resistor rather than a pot - especially in that sort of remote controller I think.

It also needs to be a logarithmic type - not a linear, and make sure you get the correct impedance.

Lethal` · 8 Dec 2010 at 23:54

Most of this is going straight over my head. I think I'm going to take it home and get a mate's dad (electrician) to take a look. Thanks for all the pointers though, it's definitely not worth just chucking out.

2bit · 8 Dec 2010 at 23:59

Lethal` said:
Most of this is going straight over my head. I think I'm going to take it home and get a mate's dad (electrician) to take a look. Thanks for all the pointers though, it's definitely not worth just chucking out.

Ah it's not that big a deal - if you fancy a go then break open the box and try any old pot you can get - just about all audio related pots are logarithmic anyway. You can't do any harm and may come out a winner.