I have a KHT 2005.2 speaker system. The sub, PSW 2010, suddenly gives a loud buzzing noise after 3 years of great service. Please advise me what to do to address this problem? I'm in Singapore and I cannot find a KEF repair shop here! Thanks for your help!

I would check the caps on the power supply. They are rather large electrolytic capacitors that will look like they burst and/or leaking. When these die, the caps ground and the sub will make a loud buzzing sound. If you are handy with a soldering iron you can replace them yourself. Replace them with the same voltage or a little bigger and same with the size.

If the cap. says 16v 4700pF on it, for example, a 20v 5300pF or a 16v 6200mF cap. will work for this application.

here is the manual, I am looking for a more detailed version

What happens if you disconnect only the source end of the RCA's? Atmospheric noise can enter through the cables if their shields are grounded well.

Google: "speakers buzzing"

I'm not too familiar with this system one thing you could try:-If the sub has separate mains power try disconnecting it from the main Amp. If it still buzzes the problem is the built in bass amp if it stops the problem is the main amp.

is probably faulty capacitors
you should check out this link: http://lug.demon.co.uk/kefrepair/?cat=1

Have just repaired a similar problem with a KEF 2500 - relay was chattering at 50 Hz rate, buzz in speaker output.

Problem was caused by overheated / dried out Electrolytic filter cap (C52 - 47uF 63V) on the relay coil supply feed.
The overheating is caused by adjacent power supply dropping resistors which run very hot due poor design of power supply.

A service manual for a similar model is available at following link, refer to power supply section:-
http://www.eserviceinfo.com/downloadsm/35375/kef_psw2000.html

To replace,
1) remove chassis from speaker cabinet (8 screws), disconnect red/black speaker wires from main PCB spade connectors.
2) Remove 4 screws attaching main pcb heatsink assembly from face panel - lift assembly from faceplate (a bit messy , much heartsink compound between mounting faces)
3) unplug the AC 3 pin connections adjacent to the large capacitors and the 3pin connector on end of pcb (near C52), then roll assembly over the top of the audio sub-board to access underside of pcb.
4) solder connections to C52 is accessible at edge of board without further dis-assembly.
Take extreme care replacing C52, as the circuit board is of poor quality, (usual domestic electronics quality) being single sided copper without plated through holes.
The board is already heat damaged by heat buildup from power supply resistors, so the track will most likely lift and crack when disturbed- to counter this problem link the +ve capacitor pigtail to an adjacent solder pad on the same track.
Assembly is reverse of above, take care to preserve/ensure minimum disturbance of heatsink compound.

yes. A good idea. Kill power to the sub, then unplug and remove everything from the sub. go ahead and plug it in again and check for buzzzz.
That is test one. if you have buzz still, its the sub assembly. bad luck, but not impossible. If the buzz is gone its one of the signals to the sub. They can produce a buzzz without any signal coming from your stereo equipment. Replace the feed line, enjoy! BTW...Kef sure does sound clean. good choice.

The KEF-Subwoofer range (from the PSW1000 up to PSW 3000?) have some built-in flaws in the electronic design.

I just fixed my PSW2000 working along the repairing instructions from:

http://lug.demon.co.uk/kefrepair/

Works! Costs have been about 35,- Euro for spare parts and some (too many) hours of work. If you are used to electronics and soldering you may make it in 2 hours.

You have a bad set of Audio output IC's for the sub. There is two of them. TDA7293 REPLACE BOTH!!!
There is 4 on one side of board,and 2 on other "also 1 small one" The the two are for the sub,the other 4 are for the main speakers/surround. They sell on Ebay for $6-10 each or a kit of all 6 for $25.

The circuit that should be turning the sub on and off based upon the presence of an audio signal is not working correctly and the sub is trying to reproduce 60 cycle hum. The unit needs service.
Dan