A few days ago my wife were going to watch some TV on our 7-channel + subwoofers surround system. I hit the TV's "On" button and nothing happened. I then noticed that all the components plugged into the circuit-protected power strip were off and wouldn't come on. I tried to turn the power strip on but its breaker tripped again immediately.
I looked to the other side of the equipment rack where the surround preamp/processor (aka pre/pro) and 5-channel power amp are plugged directly into the wall. I wondered if something was funky on that side. I unplugged the pre/pro and tried the on/off switch on the power strip again. This time it came on and remained so the TV could stay on without shutting back off again. At that point I re-configured the TV to use its internal speakers so I could listen to the audio without sending it through the surround system, which must have a short in it somewhere.
The idea of a short in a 7-channel plus 2-subwoofer system was pretty daunting at this time. There could be a problem anywhere--a burnt-out element in a speaker crossover, a short inside the pre/pro or an amplifier, even one of the self-powered subwoofers going south.
Then my mind drifted back 40 years. In 1975 I had taken a job at an audio store. The manager had a side business in disco, both permanent installations in local clubs and mobile disco for parties. A local club with a permanent installation was complaining that their Crown DC-300A amp (the most bullet-proof amp in the industry at the time) was inexplicably shutting down. We brought it to our service guys. The amp was absolutely filthy. When the repair techs turned it on, sparks arc'd across the speaker terminals, causing the protective circuitry to shut the amp down.
I'll bet you never thought that airborn dust could be a conductor. In this case, the settled dust on the back panel was sufficient to bridge the gap between positive and negative speaker terminals to cause a short. This inspired me to take a look at the backs of my speakers. I looked at the rear bases of the speakers where the speaker terminals are. Although they weren't as filthy as that Crown DC-300A amp, there was enough dust, cobwebbing, and twigs from the Christmas tree that had been down there to cause concern. I used a soft but thick dustbrush to clear the terminals of both speakers of dust, cobwebs, and leftover twigs. Then I went to bed. If this wasn't the cause, I didn't want to be up all night trying to find it.
The next day, however, I turned on the TV. It stayed on. Now for the acid test: I turned on the pre/pro, which had a 12V trigger to turn on the 5-channel amp. Everything turned on and the power strip stayed on as well. Yay!
So why would the power strip connected to one AC outlet care if the pre/pro and amp connected to a different wall outlet were connected to a shorting situation? Because the pre/pro and power amp were in standby mode. They weren't completely off, and their AC outlet was on the same circuit as the protective power strip. When turning on the power strip, there was enough current going through the standby setup on the other outlet of the same circuit that the power strip's breaker tripped, turning everything off.
Brushing the speaker terminals removed any amplifier shorts, and everything behaved perfectly. I redirected the audio from the TV to the pre/pro, and 7.2 channels of full fidelity returned.
You would be surprised at all the things that can conduct. Even tree branches and twigs can cause shorts. I know this is a corner situation, but it's good to know: if things aren't working right, don't just check your connections, clean them.
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JohnnyB
A few days ago my wife were going to watch some TV on our 7-channel + subwoofers surround system. I hit the TV's "On" button and nothing happened. I then noticed that all the components plugged into the circuit-protected power strip were off and wouldn't come on. I tried to turn the power strip on but its breaker tripped again immediately.
I looked to the other side of the equipment rack where the surround preamp/processor (aka pre/pro) and 5-channel power amp are plugged directly into the wall. I wondered if something was funky on that side. I unplugged the pre/pro and tried the on/off switch on the power strip again. This time it came on and remained so the TV could stay on without shutting back off again. At that point I re-configured the TV to use its internal speakers so I could listen to the audio without sending it through the surround system, which must have a short in it somewhere.
The idea of a short in a 7-channel plus 2-subwoofer system was pretty daunting at this time. There could be a problem anywhere--a burnt-out element in a speaker crossover, a short inside the pre/pro or an amplifier, even one of the self-powered subwoofers going south.
Then my mind drifted back 40 years. In 1975 I had taken a job at an audio store. The manager had a side business in disco, both permanent installations in local clubs and mobile disco for parties. A local club with a permanent installation was complaining that their Crown DC-300A amp (the most bullet-proof amp in the industry at the time) was inexplicably shutting down. We brought it to our service guys. The amp was absolutely filthy. When the repair techs turned it on, sparks arc'd across the speaker terminals, causing the protective circuitry to shut the amp down.
I'll bet you never thought that airborn dust could be a conductor. In this case, the settled dust on the back panel was sufficient to bridge the gap between positive and negative speaker terminals to cause a short. This inspired me to take a look at the backs of my speakers. I looked at the rear bases of the speakers where the speaker terminals are. Although they weren't as filthy as that Crown DC-300A amp, there was enough dust, cobwebbing, and twigs from the Christmas tree that had been down there to cause concern. I used a soft but thick dustbrush to clear the terminals of both speakers of dust, cobwebs, and leftover twigs. Then I went to bed. If this wasn't the cause, I didn't want to be up all night trying to find it.
The next day, however, I turned on the TV. It stayed on. Now for the acid test: I turned on the pre/pro, which had a 12V trigger to turn on the 5-channel amp. Everything turned on and the power strip stayed on as well. Yay!
So why would the power strip connected to one AC outlet care if the pre/pro and amp connected to a different wall outlet were connected to a shorting situation? Because the pre/pro and power amp were in standby mode. They weren't completely off, and their AC outlet was on the same circuit as the protective power strip. When turning on the power strip, there was enough current going through the standby setup on the other outlet of the same circuit that the power strip's breaker tripped, turning everything off.
Brushing the speaker terminals removed any amplifier shorts, and everything behaved perfectly. I redirected the audio from the TV to the pre/pro, and 7.2 channels of full fidelity returned.
You would be surprised at all the things that can conduct. Even tree branches and twigs can cause shorts. I know this is a corner situation, but it's good to know: if things aren't working right, don't just check your connections, clean them.
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