See the "Influencing electrical devices" thread on
news:sci.electronics.misc :-)

I normally leave my amplifier on all the time, even when not in use,
and have never had a problem with it for years. Last night around
4:00 AM, I was painfully awakened by very loud static coming from my
system. At first I thought it was a nightmare or something, but
eventually realized what was happening. It must have woken up my
whole building by the time i got up and turned the system off.
Incredibly, I found that the volume was turned WAY up -- I NEVER leave
the volume all the way up like that. I can only hope the speakers
weren't damaged (so far they seem okay). The volume control on this
system is an older style mechanical type -- when the remote is used,
the knob on the volume control actually dials up and down (it's an old
Adcom preamp-tuner). Is it possible that some random signal went near
my building that was the same frequency or whatever as the volume
control? That seems absurd, but I can't think what else it could be..

After I went back to bed, I had to get up again because a crazy signal
started coming from the subwoofer and I had to unplug it. The bizarre
signal is still coming through the subwoofer today when I tried it
this afternoon, so I've had to leave that unplugged. Over the years
I've occasionally had strong signals from CB radio (or whatever) come
over the subwoofer, but it's usually very brief and no big deal...it's
never a constant thing like I'm experiencing now.

Can anyone suggest what may have happened and what I can do to prevent
this from happening again?

I suppose it's possible that a neighbor in an apartment above or below
me has installed some sort of new-fangled audio or home-theater system
and that could be causing the interference....but it's just a guess.

When not using my system, I normally leave the volume all the way down
and I switch the input to auxiliary or whatever so there is no signal
coming through. But the amp and preamp are always on. After this
episode, I don't think I can take the chance and I'll have to leave it
off. But I'm still mystified by it..

This is the first time anything like this has happened....thank god I
wasn't away or they'd have had to call the fire department or
something to break the door down. THANKS!

In article ,
dege wrote:

Is it possible that some random signal went near
my building that was the same frequency or whatever as the volume
control? That seems absurd, but I can't think what else it could be..

After I went back to bed, I had to get up again because a crazy signal
started coming from the subwoofer and I had to unplug it. The bizarre
signal is still coming through the subwoofer today when I tried it
this afternoon, so I've had to leave that unplugged. Over the years
I've occasionally had strong signals from CB radio (or whatever) come
over the subwoofer, but it's usually very brief and no big deal...it's
never a constant thing like I'm experiencing now.

Can anyone suggest what may have happened and what I can do to prevent
this from happening again?

It certainly sounds as if your system is being affected by strong
radio-frequency interference. This could cause the noise from the
subwoofer, and might also cause a false triggering of the remote
control circuitry.

It might be CB (a fair number of CB owners use illegally high powered
transmitters), or amateur radio (some amateur setups can run up to
1500 watts of RF), or a commercial transmitter (although the latter is
less likely I suspect). To pin this down you'd need some form of
wide-range radio receiver. If there's a local amateur-radio club in
your area, give one of their officers a call and see if they can help
you out - oftentimes "hams" have the skill and equipment needed to
track down radio interference.

Another possibility is that your preamp has suffered an internal
failure of some sort. A dying power supply might cause all sorts of
weird symptoms, for instance.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

In article , dege
wrote:

I normally leave my amplifier on all the time, even when not in use,
and have never had a problem with it for years. Last night around
4:00 AM, I was painfully awakened by very loud static coming from my
system. At first I thought it was a nightmare or something, but
eventually realized what was happening. It must have woken up my
whole building by the time i got up and turned the system off.
Incredibly, I found that the volume was turned WAY up -- I NEVER leave
the volume all the way up like that.

I have a older AIWA pre-amp that has a motorized volume control.
I have found that breif power outages leave this unit in a
random state and in the powered-up mode. Did any of your digital
clocks do anything funky?

Do you have pets? Could a cat or a dog have stepped on the
remote or fell asleep on it? Or a kid have done this?

Is the remote infrared or RF? If it works through walls, it
is an RF unit. Other RF remotes, which are kind of rare, could
have gotten into the system. If you have an Infrared remote,
it is unlikely that another remote got to it. In this case, it
could be that some high-powered RF found its way into the cabinet
and activated the unit.

Does the pre-amp have a battery in it? Perhaps the battery is
going bad, and is currently at some voltage level that makes the
unit unstable. If it has a memory circuit, it might be that one
of the components, like a capacitor, has gone bad.

Finally, check to see if there is a way to "reset" the unit,
either with a button on the back, some switch combination, or
by unplugging it for a while.

It will be interesting to see if this is a one-time event or
something that will repeat itself over time.

-john-

--
================================================== ==================
John A. Weeks III 952-432-2708
Newave Communications http://www.johnweeks.com
================================================== ==================

you have a poltergeist, plain and simple ;-))


"dege" wrote in message
om...
I normally leave my amplifier on all the time, even when not in use,
and have never had a problem with it for years. Last night around
4:00 AM, I was painfully awakened by very loud static coming from my
system. At first I thought it was a nightmare or something, but
eventually realized what was happening. It must have woken up my
whole building by the time i got up and turned the system off.
Incredibly, I found that the volume was turned WAY up -- I NEVER leave
the volume all the way up like that. I can only hope the speakers
weren't damaged (so far they seem okay). The volume control on this
system is an older style mechanical type -- when the remote is used,
the knob on the volume control actually dials up and down (it's an old
Adcom preamp-tuner). Is it possible that some random signal went near
my building that was the same frequency or whatever as the volume
control? That seems absurd, but I can't think what else it could be..

After I went back to bed, I had to get up again because a crazy signal
started coming from the subwoofer and I had to unplug it. The bizarre
signal is still coming through the subwoofer today when I tried it
this afternoon, so I've had to leave that unplugged. Over the years
I've occasionally had strong signals from CB radio (or whatever) come
over the subwoofer, but it's usually very brief and no big deal...it's
never a constant thing like I'm experiencing now.

Can anyone suggest what may have happened and what I can do to prevent
this from happening again?

I suppose it's possible that a neighbor in an apartment above or below
me has installed some sort of new-fangled audio or home-theater system
and that could be causing the interference....but it's just a guess.

When not using my system, I normally leave the volume all the way down
and I switch the input to auxiliary or whatever so there is no signal
coming through. But the amp and preamp are always on. After this
episode, I don't think I can take the chance and I'll have to leave it
off. But I'm still mystified by it..

This is the first time anything like this has happened....thank god I
wasn't away or they'd have had to call the fire department or
something to break the door down. THANKS!

You may have had a power hit that glitched the processor. I know a guy that went to a high-end store to listen to some equipment. He walked across the carpet and touched the cabinet of the preamp which resulted in a static spark from his finger. the preamp's volume control then prceeded to climb up to the very max all by itself resulting in a blown (and very expensive) speaker.

When I was involved in real time embedded software design we always worked with the hardware engineers so that the default state of the hardware outputs prior to loading software would not result in damage. Usually they aren't worried too much about that assuming that the time it takes for the software to initialize the ports is trivial (assuming that the software DOES initialize the ports!) and make their designs to minimize hardware component count.

Not the sort of thing that you'd expect on a $3000 preamp but seems to still be quite common.

- Jeff


dege wrote:

I normally leave my amplifier on all the time, even when not in use,
and have never had a problem with it for years. Last night around
4:00 AM, I was painfully awakened by very loud static coming from my
system. At first I thought it was a nightmare or something, but
eventually realized what was happening. It must have woken up my
whole building by the time i got up and turned the system off.
Incredibly, I found that the volume was turned WAY up -- I NEVER leave
the volume all the way up like that. I can only hope the speakers
weren't damaged (so far they seem okay). The volume control on this
system is an older style mechanical type -- when the remote is used,
the knob on the volume control actually dials up and down (it's an old
Adcom preamp-tuner). Is it possible that some random signal went near
my building that was the same frequency or whatever as the volume
control? That seems absurd, but I can't think what else it could be..

After I went back to bed, I had to get up again because a crazy signal
started coming from the subwoofer and I had to unplug it. The bizarre
signal is still coming through the subwoofer today when I tried it
this afternoon, so I've had to leave that unplugged. Over the years
I've occasionally had strong signals from CB radio (or whatever) come
over the subwoofer, but it's usually very brief and no big deal...it's
never a constant thing like I'm experiencing now.

Can anyone suggest what may have happened and what I can do to prevent
this from happening again?

I suppose it's possible that a neighbor in an apartment above or below
me has installed some sort of new-fangled audio or home-theater system
and that could be causing the interference....but it's just a guess.

When not using my system, I normally leave the volume all the way down
and I switch the input to auxiliary or whatever so there is no signal
coming through. But the amp and preamp are always on. After this
episode, I don't think I can take the chance and I'll have to leave it
off. But I'm still mystified by it..

This is the first time anything like this has happened....thank god I
wasn't away or they'd have had to call the fire department or
something to break the door down. THANKS!

"Andy Fish" wrote in message ...
you have a poltergeist, plain and simple ;-))


"dege" wrote in message
om...
I normally leave my amplifier on all the time, even when not in use,
and have never had a problem with it for years. Last night around
4:00 AM, I was painfully awakened by very loud static coming from my
system. At first I thought it was a nightmare or something, but
eventually realized what was happening. It must have woken up my
whole building by the time i got up and turned the system off.
Incredibly, I found that the volume was turned WAY up -- I NEVER leave
the volume all the way up like that. I can only hope the speakers
weren't damaged (so far they seem okay). The volume control on this
system is an older style mechanical type -- when the remote is used,
the knob on the volume control actually dials up and down (it's an old
Adcom preamp-tuner). Is it possible that some random signal went near
my building that was the same frequency or whatever as the volume
control? That seems absurd, but I can't think what else it could be..

After I went back to bed, I had to get up again because a crazy signal
started coming from the subwoofer and I had to unplug it. The bizarre
signal is still coming through the subwoofer today when I tried it
this afternoon, so I've had to leave that unplugged. Over the years
I've occasionally had strong signals from CB radio (or whatever) come
over the subwoofer, but it's usually very brief and no big deal...it's
never a constant thing like I'm experiencing now.

Can anyone suggest what may have happened and what I can do to prevent
this from happening again?

I suppose it's possible that a neighbor in an apartment above or below
me has installed some sort of new-fangled audio or home-theater system
and that could be causing the interference....but it's just a guess.

When not using my system, I normally leave the volume all the way down
and I switch the input to auxiliary or whatever so there is no signal
coming through. But the amp and preamp are always on. After this
episode, I don't think I can take the chance and I'll have to leave it
off. But I'm still mystified by it..

This is the first time anything like this has happened....thank god I
wasn't away or they'd have had to call the fire department or
something to break the door down. THANKS!


I think I know the source of your problem. There is a series of Sony
receivers (STRAV-570, for one) that has this exact problem. Sony used
the chassis to complete the ground path between 2 points on the pc
board. When the screws get loose over time, a voltage potential
between these 2 points results. When the circuit contains the
microprocessor, sometimes you get a voltage between 2 points on the
same IC that are both supposed to be ground. The easy solution to the
problem is to tighten every ground screw on every pc board in the
preamp, including any wires that attach to the chassis with screws.
The best solution is to solder ground straps (using braid or solder
wick) from all points on the pc boards (where there is a ground pad
located at the screw hole) to the chassis. You will have to scrape a
bit of plating off the chassis in order to solder to it.
This grounding problem also shows up as unwanted signals in the audio
chain. The Sony STRAV-920 and 1020 and the Aiwa versions of those
receivers had a high pitched whine (not from the customers) in the
audio that went away when you tightened the screws on the pc board.
Sony's solution in their service bulletin was to add lock washers to
the screws and retighten them. Duh! I added ground straps and the
problem never returned.