Can I use any cable to connect the subwoofer, for a Technics sa-ax530 receiver

Not a good sign. There should be a click a few seconds after you turn on the unit. That says the output section is OK. If there is no click, you need repair. Perhaps only some fuses inside, but it could be worse.

Also make sure that the speaker switch is in the right position, like A, not A+B. Also the headphone jack can silence the speaker.
Make sure that ALL switches are in the right position.

Hello, I searched all thru the service manual of the Technics SA-AX530 Receiver, and I have to say that there is not any way to turn the volume of the subwoofer up (or down) alone. The only control of the sound that affects the subw. level is the BASS control, but it controls also the bass at the speakers too.
Good luck.

Only connect audio...you do not have a video option available with this unit but the optimal connection is always audio only between TV-receiver.

Connect any RCA cable jack of your choice from the audio out connection on the TV it may be labeled as "variable audio out" or simply "audio out" into the audio left and right channels of the TV section of your receiver. Be sure the channel connections between the receiver and TV match up and power it all on, connecting is finished.

Since it only drives a self-powered subwoofer's amplifier the impedance of the downstream speaker on matters to THAT amplifier.

You need a cable (from Best Buy or Radio Shack) that is "Mini" jack (Ipod end) and dual RCA on receiver end.

This manual discusses it somewhat.

http://service.us.panasonic.com/OPERMANPDF/SAAX730.PDF

Basically, feed the self-powered (active) subwoofer from the Subwoofer Out. There does not seem to be a way to adjust the subwoofer output to match the rest of the speakers because the sub out is muted during the adjustment procedure.

Another way would be to refer to page 15. The note at the bottom right suggests your subwoofer might accept full range speaker level inputs. Refer to the manual for your sub. I believe they mis-printed it and meant "active" subwoofer, as simply wiring a passive (unpowered) sub across the front speaker outputs might cause some amplifier overload issues and you would have no way of balancing it anyway.

check for shorts on the speaker terminals

An amplifier should never be turn on without speakers, it will overload internally.
make sure speakers work and try again.

There is likely separate gain controls for your surround channels on this receiver and they are probably set at -10dB. Enter the setup menu labled "level" and increase the amount for each channel equally.