technics sa gx690 wont power up?

The 'protect' mode on the amplifier indicates 1 of 2 problems:

PROBLEM 1. Shorted wire. Test this by pulling all the speaker wires out of the back of the amplifier and then turn the amplifier off and then on again. If the amplifier doesn't go into 'protect mode' with no speaker wires attached, it's okay and you can put your wires back in again but check the connections on speakers and the amp to make sure no little strands of speaker wire are touching each other or anything but the terminal itself.
* A hint when behind the amplifier and reconnecting your wires again, to find out which speaker is which, pull a AAA or AA battery out of one of your remotes and touch the speaker lead (still connected to the speaker) and you will hear a little "pop" it's an easy way to identify speakers.

PROBLEM 2. Circuit board. If the amplifier goes into 'protect' mode when turned back on and while all the speaker wires are not in the back of it - your circuit board is stuffed. In most modern amps, the power supply and DSP board in the amp are combined as a single unit ... like a proprietry board (meaning only the manufacturer has the parts and no after market parts can be used to fix it). In this case it is usually far too expensive to fix it and you would probably just get a new amp.
An example, I have a pioneer amp that had this issue - it costs $450 Australian to buy ... the new board on it's on cost $450 and $65 labor ... where I can buy a new Onkyo amplifier for $550 Australian and not have this problem because the board and power supply are separate units (and to fix the power supply is only $40). Either way, if you have PROBLEM 2 take the amp into a place that does free quotations so they can asses your cost.

I hope this helps and I hope you only have problem #1

Jason
January 2008