Hi Gorman,
no, sorry, no progress there yet. But all Squeezebox models I know
(Boom, SB3 Classic, Transporter) share this problem.
Keeping the heater wires powered all the time does not damage anything,
except your power consumption bill. And it is necessary if you use your
SB for any information display while it is not in use, the most popular
of which is probably the clock "screensaver".
The heat coming from the other chips is a clear indication that saving
power was not a priority in SlimDevices design department. The CPU will
need some power to enable switching the unit on via infrared remote
control. It is also permanently connected to the SqueezeBox Server if
you have one, which means that you can power the device on anytime by
just selecting it and having it play anything. It will start
immediately, from standby as well as powered idle state. So at least the
Ethernet / Wi-Fi and the IR receiver are permanently on, and also the
parts of the CPU that make use of it. So it wouldn't be wise to cut them
off from power because you would have to power cycle each time you want
to use it. That's not far from just pulling the wallwart plug which I
would recommend more.
Nowadays system designers would use a lot of tricks to save as much
power as possible. There are generations of new chips that could power
down to as well as nothing at all, and still wake up from that in
fractions of a second, but being 100% functional regarding the features
that should be available during standby. It's just not a concern because
Slimdevices / Logitech didn't think of it, either because these chips
didn't exit back then, or they didn't feel the need to use power saving
features much. Consumption awareness is something rather new eventually.
So we won't ever be able to save more power beyond switching the display
filament off. I think that might cut standby consumption by 30 to 50
percent, and is an operation that the display and the CPU won't even
notice so they will play along well. As soon as we interrupt power in
any component that was designed to be always on, we will get in trouble.
I know now that the filament voltage is only 5 Volts on the left and
between 2.1 and 3.2 Volts on the right side. There are multiple
questions here, everybody is very welcome to join the discussion:
- What if the left side is disconnected (floating) while the right
side isn't, or vice versa? If one side is floating, I think the
heaters should no longer emit any electrons because there is no
current to carry them, at least not completely across. But some might
spill from the powered end, causing some pixels on that end to stay
lit even though we want the entire display to be dark
- What if we switch the "disconnected" side to ground instead of
leaving it floating? Probably not a good idea because then we will
have current, and consequently electron emission, albeit a fraction of
the emission in powered state. But still, more power than needed would
probably be consumed and the display might not be entirely dark either
- Eventually we might need to use the cleanest but most challenging
solution and disconnect both ends of the filament, i.e. two relays /
mosfets or whatever which adds to the complexity of the circuit needed
It all makes sense only if we can reliably differentiate the standby
mode from any powered mode (idle or playing) so the display is
automatically shut down when not needed. I would hate to add an ugly
hardware button or switch to take care of it. At the risk of repeating
myself, Logitech won't publish any documentation so we are on our own
here. While the display end of the solution works the same in every VFD
Squeezebox, detecting the power mode will probably differ a lot between
device models. It is not made easier by the fact that almost any chip in
the device seems to stay powered regardless of the overall power mode.
I'll be grateful for any ideas.
The SB boards are works of art, too, I guess they have 6 or 8 layers, so
it is not even clear whether any useful signal can be found by probing
any position in the only two layers available to us.
So this is an ongoing challenge, and my time is getting shorter. Sorry
but there won't be much progress any time soon.
Have a nice weekend!
Regards
Joe
5x Squeezebox Classic SB3
2.5x Squeezebox Boom
1x Transporter
1.5x Controller
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