Audio Systems: Sony Amplifier - STR-DG710 - Protect Error, sony amplifier, thermal conductor

Question
I'm receiving a "Protect" error when I turn the volume up on my amp at a level that I don't think is too outragious (46). My research tells me that it's like an impedance issue, but I'm hoping you can help me troubleshoot a bit more.  I suspect the problem exists because of my home audio setup. A little background: I built my house 15 years ago before whole home speaker/audio setups were main stream. As such I created my own. I have 6 zones throughout the house. For those zones with more than one room I've run the speakers in series to keep the impedance in check. The "consultant" / friend who helped me instructed me to do it this way to avoid what I think may be the problem I'm facing.  My Question: Is there a way to isolate and correct the problem? And if not, is there a "device" that I could use to "regulate" the ohm impedance?

Answer
The most often external cause of protection overload is shorts in the speaker wiring or a speaker with a shorted voice coil; either of which is placing an unusually heavy load on the amp that is connected to that shorted condition.  Anything that will lower the impedance will cause the overload.  In your case you should check all the speakers to see if anyone of them is not working or is way low in output.  This will give you a clue indicating that speaker may be in trouble.

Another easy way to check for external problems is to disconnect all speaker wires at the back of the amp.  Then, run the volume up with no loads and see if it still fails - which would mean there is an internal problem.  If it is okey with no loads connected, then connect only one at a time and see if just one speaker line it the cause.

The most common cause from internal problems is when the amp gets old and tired the silicon grease washer on the output transistors gets dried out and goes hard.  It no longer is a good thermal conductor for getting heat from the output transistor into the heat sink it is mounted on.  You can check this by putting your finger on the output transistors after the system shuts down; if any one of them is really hot to the touch that is a good indication.  The easiest way to correct for that is replace the amp/receiver.  Repair often costs as much a good receiver.  Or, if you know how to regrease them you  can do it by yourself for a few dollars.  Lots of labor, though, because the transistors must be desoldered and pulled off; old grease removed, mica washers replaced and regreased with silicon heat grease.

Hope this will help.
C