I have a very old amplifier (Marantz Model 140). It has been working
very well for almost 20 years. Yesterday when I switched it on, the
speakers came with a continuous, very, very loud "wool" / "wow"
sound, and the power indicator on the amp showed that it had reached
the maximum power. This situation didn't change even I tuned the
volume of the amp to the minimum. The whole thing just terrified me. I
wonder what the problem is. Is it because of a kind of 'short-circuit'
between the contacts of speaker cables? Does anyone experienced this
before and know WHY it is so? Will it harm the speaker? I would know
how to fix the problem before turning on the amp again cos I have no
idea if it will do irreversible damage to the speakers if I continue
to 'experiment'with it ...

I love that amp although it is very old ...

Charles

Charles, It sounds like a power supply problem. Possibly a bad
electrolytic capacitor or rectifier diode. To protect your speakers, I
wouldn't use the amp until it's repaired. If it was mine, I would
replace the rectifier diodes AND electrolytic caps.

-MIKE