Suspected mercury switch problem on yamaha htr-5440

[pfa]

I've had this yamaha tuner for 4 years now and it's always had this
problem whenever I move the unit (typically to change
connections...it's in a cabinet I can't get behind it) I hear clicking
sounds (high pitched "ping" sort of sound) and invariably a few of the
speakers don't work or have low volume. I suspect this is a mercury
switch. I realise I should have the unit turned off and after the first
couple of times I wised up to that but it doesn't seem to be relevant.
The unit is so sensitve that even when the dog tosses a ball around
near the unit the bounce of the ball (on the nearby floor) can trigger
this. Needless to say this is REALLY annoying. I've found sometimes the
only way to get all the speakers working is to lift the unit up at the
front and put it down again (which usually but not always works).
Sometimes the unit just makes this clicking noise when there's been no
vibration.

Can anyone clue me in as to what's going on here and how I might
rectify it? Could it just be a faulty unit (not much good to me if it
is seeing no warranty and repair means it's probably easier to just
replace it)?

[Rick]

"pfa" <peter@falson.net> wrote in news:1125334776.290443.64270
@z14g2000cwz.googlegroups.com:

> I've had this yamaha tuner for 4 years now and it's always had this
> problem whenever I move the unit (typically to change
> connections...it's in a cabinet I can't get behind it) I hear clicking
> sounds (high pitched "ping" sort of sound) and invariably a few of the
> speakers don't work or have low volume. I suspect this is a mercury
> switch.

I seriously doubt it has anything to do with a mercury switch. In fact, I
doubt there are any mercury switches in the unit. IMHO - it's far more
likely that the "clicking" sound is a relay controlling the output(s) to
the speakers. Many amplifiers (especially older models) use this sort of
setup for overload/overcurrent protection. When an overload condition is
detected, a relay is activated which cuts off the output to the speaker(s).
That way, you avoid burning up the final output amps when speaker wires are
accidently crossed, speakers/x-overs short out, users wire in speakers with
the wrong impedance, etc.

If this is the case and you have to move things around to get it to come &
go, then there are a couple of things you can take a look at:

1. Examine all of your speaker wiring. Pay special attention to any frayed
wiring, wires hanging on by only one or two strands, broken insulation
where the two wires may be just barely touching (you normally see this when
pets have been gnawing on the wire), etc. Also make sure that where the
wires connect to the unit, that none of the strands are frayed and possibly
touching any metallic part of the unit other than the speaker connector
itself.

2. Check all of your speakers and the unit for impedance values. When a
unit specifies 4 or 8 ohm impedance for all speaker outputs, it does so for
a reason. Plugging in 4 ohm speakers to a unit rated for 8 ohm impedance
can result in problems like what you are describing. Also, I've run across
several cases where people have tried wiring 2 or more speakers into one
speaker output on the amp without realizing what that does to the overall
impedance value. Rule of thumb is: 1 speaker per speaker connector AND make
sure the impedance of the speaker matches the rating of the amp's output.

3. If the above all looks good, then disconnect all of the speakers from
the unit (with it turned off of course). Then fire it up and see if you can
get the clicking sound by moving the unit around. If you do, then the
problem is within the amp itself. There is one last thing you might be able
to do. With the unit completely unplugged, remove the covers, hold it
upside down and shake it around to see if there is anything loose within
it. It is also a good idea to go to Radio Shack and buy a can of compressed
air, then use it to blow out the unit while you have it opened up. This is
especially useful for those who have cats who like to lie on top of the
nice, warm amp. I've seen some amps that had 1/2" thick matting of cat
hairs inside the unit which lead to overheating damage/problems.

> Can anyone clue me in as to what's going on here and how I might
> rectify it? Could it just be a faulty unit (not much good to me if it
> is seeing no warranty and repair means it's probably easier to just
> replace it)?

It might be a faulty unit, or it might be a unit running right at the edge
of an overload condition, or it might have a frayed wire somewhere making
intermittent contact with ground, etc. Not enough info to really know for
sure.


--
Rick Simon rsimon@cris.com

Include "spam(trap)key" somewhere in the
body of any email to avoid spam filters.

[pfa]

Thank you so much for such a detailed reply (and the education).

The best idea I thought was point 3 which is what I did first (though I
must admit I have extended a couple of cables with twisted wires which
might have been the problem...or perhaps that's CAUSED a problem).

So, I disconnected the cables and when I lift the unit up and place it
down I still get intermittent click-click sounds (not regular). The
only things plugged in now are the input video/audio cables which seem
pretty prestine to me.

So....looks like I'm pulling the cover off...

[C what I mean]

Sounds like a bad solder joint or connector internally.

"pfa" <peter@falson.net> wrote in message
news:1125347940.490009.26440@f14g2000cwb.googlegro ups.com...
> Thank you so much for such a detailed reply (and the education).
>
> The best idea I thought was point 3 which is what I did first (though I
> must admit I have extended a couple of cables with twisted wires which
> might have been the problem...or perhaps that's CAUSED a problem).
>
> So, I disconnected the cables and when I lift the unit up and place it
> down I still get intermittent click-click sounds (not regular). The
> only things plugged in now are the input video/audio cables which seem
> pretty prestine to me.
>
> So....looks like I'm pulling the cover off...
>

[pfa]

I think you might be right. I did find a very strange bit of
connectivity. What looked look a small - floating - circuit board with
a square section broken off is (I think) a small board designed to
co-exist around a larger board. There was a slight crack in one of the
solder joints. I bent the "floating" board slightly to lesson the
crack. This seems to have reduced the occurrence of the problem to
"very infrequently" but not entirely. The next time I'm fed up with it
I might tempt fate and add some new solder to the joint to see if that
indeed was the problem.

C what I mean wrote:
> Sounds like a bad solder joint or connector internally.
>
> "pfa" <peter@falson.net> wrote in message
> news:1125347940.490009.26440@f14g2000cwb.googlegro ups.com...
> > Thank you so much for such a detailed reply (and the education).
> >
> > The best idea I thought was point 3 which is what I did first (though I
> > must admit I have extended a couple of cables with twisted wires which
> > might have been the problem...or perhaps that's CAUSED a problem).
> >
> > So, I disconnected the cables and when I lift the unit up and place it
> > down I still get intermittent click-click sounds (not regular). The
> > only things plugged in now are the input video/audio cables which seem
> > pretty prestine to me.
> >
> > So....looks like I'm pulling the cover off...
> >