QuestionQUESTION: 2 weeks ago my mid-90's Sony receiver (STR-D511) started overheating while playing the turntable. Turned it off, let it cool down, but when I turned it back on the next day it started flashing "Protect" if I turned up the volume at all. Figured it was old and burned out and replaced it with a Sony STR-DG820.
However, this brand new receiver starts flashing Protect as soon as I drive the volume up to a normal level. All components are unplugged, just playing an FM station, and this is still happening.
Did buy new Polk Audio R50 speakers about 3 weeks before this all started and since all other components are unplugged wonder if that's the problem. The speaker impedance is 8 ohms, so that would seem to be compatible with the receiver, but ...
The manual for the receiver says this message is generated by a short circuit, but nothing else plugged into the surge protector is having problems, and plugging the receiver into a new surge protector doesn't help either.
Any understanding into this dilemma would be greatly appreciated. Thank you.
Dan
ANSWER: For starters, a surge protector will not protect your gear from a short circuit, all it does is protect against power spikes in the the supply.
What kind of interconnects have you been using for your other components? If they are the "directional" cables, get rid of them and buy some properly terminated interconnects. If used improperly, these so-called directional cables can severely damage the amplifier.
As a side note - audio is an AC waveform - it travels in BOTH directions on the cable. The "directional" cables have the ground disconnected at one end as an attempt to battle ground loop issues. These are typically overpriced and never endorsed by any professional audio engineers (at least none that I've ever met...).
There may be an issue in one of the speakers causing an impedance mismatch. If you can - check the impedance of each speaker using an ohmmeter or multi-meter, and see if they match.
I hope this can help you.
Best of luck.
---------- FOLLOW-UP ----------
QUESTION: Hi Wayne.
Since I had disconnected all components but receiver and speakers, decided to see if hooking up my original receivers would put the problem on the new speakers. So here's what I did and what happened.
Unhooked the new speakers, and then hooked up only the right speaker with the one of the old ones. Was able to crank the volume to a level I wouldn't go much past, and no problems. So, then I hooked up the other old speaker on the left, turned the receiver back on and started to raise the volume.
At about half the volume I'd reached with just the right speaker, the "protector" message started to flash. I then unhooked the left speaker to retest the right and now I get the "protector" message with just that speaker.
Checked the manual for the new receiver and it says this message is displayed when "Irregular current is output from the speakers."
First, having always thought that the speakers simply received signals from the receiver then outputted sound, this was a new concept for me. But second, though I could understand why a new pair of speakers might be doing this (they're defective), I don't understand why my old speakers (which worked fine, just needed new woofers) would suddenly be doing this.
Any further light you can shed on this is truly very much appreciated.
Dan Johnstone
Portland, OR
AnswerI'm thinking that the new speakers are causing the problem (or one of them). I'd seriously think about getting a multi meter on those speakers to take some ohm readings.
What I'm guessing is that one of the speakers shorted, popped an internal fuse on the receiver.
Any signals in your system are part of a circuit, which means they will travel both ways (+ and - on speaker terminals illustrate this). If something goes haywire with a speaker, it can (and many times will) affect the amplifier in the receiver. It would explain why you are getting that message with whatever speaker you use - that particular channel is messed up now.
Unfortunately, I don't think that this is a DIY fix.
