OVERLOAD Connecting a KEF PSW 1000.2 subwoofer to Technics SA- DX750 R & L speaker connections results in OVERLOAD after a crash sound usually higher in sound than a lower bass sound. The rca connection to the subwoofer does not seem to work on the subwoofer at all. Can you recommend a solution.

It's not clear if this has EVER worked or what is new in the scenario. The STR manual has setup instructions for supporting a sub. If you want to prove the sub itself works you could jack any source like, say, a CD player, into it to prove its amp will respond BUT IT WILL BE LOUD if it works.

Your amplifier is bad. I sent mine to KEF in NY and they fixed it for $100 US.

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

If it came actively powered and permanently connected but you do not want to use the supplied amplifier, then you need to disassemble the subwoofer cabinet and disconnect the amplifier from the driver.

Manual posted at the following link:
http://lug.demon.co.uk/kef/psw2150_user_manual.pdf

Have you got the sub defined to the Onkyo correctly? Try conencting the sub's input to one of the Tape Out connectors and play some FM through it. That will prove if the sub is alive. The nwe can troubleshoot the correct failing device.

The question is what is causing the overload? The power supply or the output devices on the heat sink?
If you have accidently shorted a speaker wire, then the answer will be output devices, otherwise it could be anything in the power section. You may find a burnt or damged device with either of the causes.

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.

Have you tried connecting speakers? What was the result?

Yes, when you turn the volume up on these amps (or when the output gets past a certain level) the cooling fan should automatically come on.

you can simply and easily replace 3 capacitors on the main amplifier board (c58 - 47uF 63v or 100v) + (c52 & c53 - 220uF 25v) but stand them away from the board on the length of the capacitor leads to prevent them from absorbing heat from surrounding hot components (with heat shrink tubing to prevent shorting)

these are usually the cause of most problems with KEF PSW subs, as for it sounding wooly, this is just the way it is, mine is the same.