Sub-woofer not working. Plug fuse OK.

Crabman

Hi folks

The sub-woofer that is used for PC sound recently stopped working.

It has its own power supply and four satellite speakers connected.

It simply won't switch on and despite testing the plug fuse I can't get it to work. Is there anything else I can (safely) test to try and diagnose the problem?

It came with the PC a few years ago and is branded "We Ifi" with model number "D-4100."

Thanks

Benet

Hello, I know you mention they're branded with "we-ifi" but is it possible they're made by Sony?



They're the only speakers I can find online with that model number.

Crabman

Thanks for the response, this is what it looks like:



I have opened it but didn't really know what to look for aside from any disconnected wires.

bluesnake

does the green light come on? if not it is most likely power related, fuse in plug and internal fuse.

Ximian

Crabman, do any of the satellite speakers work?
As bluesnake said: Does the unit power on, any lights when you switch on the unit/plug it in? There might be an internal fuse on the circuitboard that's blown. have you checked?
The subwoofer box will also house the transformer and bass level and volume/balance controls for all the speakers. It could be a problem with the internal transformer or the circuit board and possibly the power supply cable. I had a Creative Labs 2.1 speaker system a few years ago that just stopped working, the issue was with the internal power supply housed in the subwoofer. It wasn't worth repairing and I bought a new Logitech 2.1 speaker system.

Crabman

Thanks both.

The green light no longer comes on and the fuse in the wall plug has been checked with a multi-meter.

I can take another look inside to see if there's a fuse, I didn't notice one.

The internal transformer is a good suspect, the unit has been switched on for several hours each day for the past few years even when the PC was in sleep.

Something else I could try is plugging it in and using the multi-meter to test the voltage within the box. I realise this carries risks. I'm more used to using the meter to test temperature or voltages up to 12V.

bluesnake

Crabman wrote: »

Thanks both.

The green light no longer comes on and the fuse in the wall plug has been checked with a multi-meter.

I can take another look inside to see if there's a fuse, I didn't notice one.

The internal transformer is a good suspect, the unit has been switched on for several hours each day for the past few years even when the PC was in sleep.

Something else I could try is plugging it in and using the multi-meter to test the voltage within the box. I realise this carries risks. I'm more used to using the meter to test temperature or voltages up to 12V.

Well at a guess, suspect it is the amp psu (no green light). While transformers do go faulty, it more common for electronics to die first. The amp circuit will approximately consist of 3 or more sections, put onto 1 board. The section are power supply, signal splitter, and amp.

Firtly I assume you are competent around mains voltage and electrics, so measure the 240v going to the transformer and check the output voltage too. measure these on the transformer.

If the circuit has a switched mode psu, then you may as well forget fixing it as it is way out of your experience level.

Often on the printed circuit board there is a fuse, look at the writing as ir could also be labled 'FS1', check it.

Think from here on a nice clear colour closeup photo may help, but without a circuit diagram is a bit harder.

Crabman

Thanks bluesnake. Photos:

http://oi62.tinypic.com/20f3h1t.jpg
http://oi61.tinypic.com/4u6mnk.jpg
http://oi62.tinypic.com/eqqwdt.jpg
http://oi60.tinypic.com/11kz03r.jpg
http://oi59.tinypic.com/fefi2g.jpg

I've tried to test the voltage going into the transformer but none of the wires are exposed (at least not that I've noticed upon looking closely).

There is a fuse within the black housing on the red wire between the transformer and the switch, I've tested its continuity and it's fine.

espresso

Crabman wrote: »

Thanks bluesnake. Photos:

http://oi62.tinypic.com/20f3h1t.jpg
http://oi61.tinypic.com/4u6mnk.jpg
http://oi62.tinypic.com/eqqwdt.jpg
http://oi60.tinypic.com/11kz03r.jpg
http://oi59.tinypic.com/fefi2g.jpg

I've tried to test the voltage going into the transformer but none of the wires are exposed (at least not that I've noticed upon looking closely).

There is a fuse within the black housing on the red wire between the transformer and the switch, I've tested its continuity and it's fine.

Measure the transformer output voltages by following the wires back from the transformer to the connectors on the non component side of the circuit board:

Black to each yellow should be 12.5VAC
Blue to blue should be 9VAC

The transformer appears to have a built in thermal cutout, which may be non resetable.

Crabman

espresso wrote: »

Measure the transformer output voltages by following the wires back from the transformer to the connectors on the non component side of the circuit board:

Black to each yellow should be 12.5VAC
Blue to blue should be 9VAC

The transformer appears to have a built in thermal cutout, which may be non resetable.

Thanks espresso, tested both connectors on the rear of the circuit board, both readings are 0V.

So, it looks like the transformer is at fault here... I see it's removable with two bolts. Only issue is that the wires appear to go into the unit with no detachable connectors. I can solder but not sure whether replacing the transformer is a viable option.

espresso

Crabman wrote: »

Thanks espresso, tested both connectors on the rear of the circuit board, both readings are 0V.

So, it looks like the transformer is at fault here... I see it's removable with two bolts. Only issue is that the wires appear to go into the unit with no detachable connectors. I can solder but not sure whether replacing the transformer is a viable option.

The transformer output wires go to plugs which fit into sockets on the circuit board. The mains wires would need to be unsoldered from the fuse and switch.

I would guess that the thermal cutout has popped. If this is visible on the transformer, it could easily be replaced quite cheaply e.g. here otherwise a new similar transformer would be needed to repair the unit.