Hi everyone,
just a quick update on my effort to get technical info from Logitech:
they expressly told me they are not going to release technical
documentation for any SlimDevices / Logitech Squeeze* device. What a
pity.
During the recent repairs, I have learnt some new things particularly
about the Boom so besides display replacement, I can also offer you
fixes for these issues:
- unstable power connection (mechanically): the 5.5/2.1mm power jack
(in the Boom) and the plug (end of the power supply cable) may produce
a weak electrical contact because the center contact in the power plug
is basically a spring that wears out over time. The symptom is that if
you move the wire close to the Boom end, the Boom loses power for a
short period of time. No matter how short, it will either reset
instantly or even stay off. Speakers may emit a loud click because the
system was not designed for this type of power loss. I can replace the
connectors on both ends with quality parts
- bass woofer distortion: the rim around the bass woofer outer edge
that connects the moving cone to the metal frame may fissure over
time. You may notice this as the "farting bass" syndrome where low
frequencies are no longer played cleanly but with some additional
noise. It is best perceived by playing a clean 30Hz or 50Hz sine wave
(I can supply OGG samples if you want). The tearing occurs because the
bass chassis are moved with a rather excessive ampliture in order for
the Boom to achieve its famous strong bass. The connecting element is
a paper-thin piece of foam, very flexible in order to allow maximum
movement for the cone. It is subject to considerable mechanical stress
during playback. To make things worse, some Boom units have a rather
sharp edge around the place where the bass woofer is mounted. When the
bass is loud enough, it may touch this edge, further weakening the
material. However, the entire sound system does not work without these
elements because the case needs to be rather tight - that is why
you'll notice a sealing rubber strip between the outer case and the
piece on which the speakers are mounted (if you disassemble it as far
as this). If the rim is just cut / scrapped and the bass cone swings
freely, you will have as well as no bass anymore because the case no
longer participates in the sound creation. So a repair is needed
anyway. There are some fresh woofer units available, furthermore I can
now fix broken bass woofers and provide a new connecting rim. I'll
post a guide here shortly on how to do this
- left / right edge display fading: occurred to me right after
replacing an old display when I found that the new one didn't look at
all like new. It took me hours of investigation to find out what
happened. Noritake calls the phenomenon "filament starvation", and it
basically means that the filament voltage drop is too low (between
the left and right connectors). The filament is the heating wires in
front of the display grid which emit electrons and which is usually
supplied with ‎5V on the left and between 1.6 and 2.5V on the
right (depending on the brightness setting). Some Squeezeboxes
provide the desired lower voltage just for a short time, then ramp up
to a higher voltage, reducing the overall voltage drop and thus the
electron emission from the filament. This causes the display to look
rather dark and uneven. The display's left edge shows the symptom more
strongly (on about 12..16 pixels width) whereas the right edge is
darkened but typically less than the left. My solution is to pull the
right filament voltage down with three 1N4148 diodes in series from
the rightmost three pins to GND. It is kind of a bypass. Each diode
has a typical voltage drop of ~0.7V which in total ensures that the
voltage is never more than 2.1V above GND. This is the closest
average to the range of voltages I measured at this end. This ensures
a good-looking display no matter what the voltage originally supplied
by the mainboard is, and works fine with all brightness levels. It
would certainly be better to understand the root cause and fix that.
Alas, as we know now Logitech won't support us here. The SMD parts
responsible are tiny beyond recognition. I noticed that some really
small components behind the display become red-hot in the affected
units but it's useless to just replace any of them without knowing
exactly
So if a display looks like it is fading, there are two possible reasons
now. In future repairs I'll check the voltages first and see whether
they contribute to the visual problem. Usually the displays are fading
after a few years of usage but if they were kept off most of the time,
they have good chances of lasting. So it depends heavily on the usage.
Unfortunately there is not much use in turning the display off if the
Boom is supposed to act as a bedside radio and alarm clock. It seems to
be the standard usage scenario for Logitech. But if the Boom is standing
around most of the time without being watched much, it does not hurt to
switch the display off. I still recommend to keep the display off
whenever possible, and to never exceed the brightness level "3 of 5".
Regards,
Joe
5x Squeezebox Classic SB3
2.5x Squeezebox Boom
1x Transporter
1.5x Controller
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