| Issue:
USB Mighty Rat Works Fine, Then Stops Working. Cause:
The Mighty Rat is a USB Keyboard device with a default status as a High Priority
USB Root Hub Device. USB
devices with High Priority are supposed to be kept active by the computer 100% of the time, while
some other devices are put to sleep when
idle. The USB Root Hub waits for an idle device to generate an interrupt request
before returning it to active service. This is done to save power.
It appears that in a number of
cases, the USB Mighty Rat has INCORRECTLY been allocated a low priority by the system.
In that situation if the Mighty Rat sits idle for an appropriate time (around 3 to 5 minutes seems to be the
norm) the computer may simply stop looking at it. When the left or right arrow
command is triggered it sends an interrupt request to the hub, which then waits
for some data to arrive. Unfortunately, the arrow command WAS the data. This not
only contravenes the USB protocol, but also common sense. In some instances the
USB hub even ignores interrupt requests, and continues to stay idle.
This problem only seems to affect some laptops
running Windows XP Service Pack 2. Mac and other Windows platforms are
unaffected.
A simple check for USB Mighty Rat & PC compatibility is to
test, leave idle for 5 minutes and then test again. If no glitch is experienced
then it is unlikely that one will appear later on, but to be safe take the following action.
Fix#1: There's a setting in "Control Panel" >
"System" > "Device Manager" for the USB Root Hub
components. Under "Universal Serial Bus controllers"
> right click "USB Root Hub" select "Properties", and you will see a setting in "Power Management"
which allows the USB device to be sent to sleep. Un-checking "Allow the computer
to turn off this device to save power" has fixed the problem in all known cases.
If you have multiple Root Hubs listed you should repeat
this procedure on all of them.
Fix#2: If the Root Hub is
unkind enough to go to sleep DURING a PowerPoint Presentation, then an extra
button click should wake it. If that is unsuccessful, we advise that you should
pull the Mighty Rat's USB connector from the PC's socket and simply plug it back
in again (yes, during the show). That will wake up the Root Hub and put you back
in business, and no you won't get a pop up message over the top of your
PowerPoint Slide. As soon as possible after the end of the presentation we
advise that you instigate Fix#1, which will take about a minute and does not
require a restart.
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| Issue:
My Slides Advance Twice on One Click. Cause: This issue concerns
the use of RF slide advancement products in a stand alone configuration, when
controlling Notebook Computers with 400MHz Front-Side Bus speeds. Does not
affect equipment purchased after February 2006.
Notebooks typically radiate large amounts of RF noise as they are generally
cased in plastic and not well shielded. In addition they are often prone to
inject noise into the power lines via the power supply, and to top it off, the
LCD Screen can even behave as an antenna. In any PC the Front-Side Bus is a
notorious generator of RF noise. A computer with a 400MHz Front-Side Bus can
produce intermittent components at other frequencies, and if you are unlucky
they can sweep through the 433MHz carrier frequency of the RF slide advancement
gear. If this occurs during a button press, the result can be that the RF
Receiver sees two button clicks instead of one, because the brief burst of
in-band noise will interrupt the transmission, which then resumes when the noise
goes away. The duration of such a burst is typically less than 100 milliseconds.
If you experience this issue then you have a number of choices:
Fix:
- If you own a Cue King you should draw power for the RF
Receiver from the Cue King via a microphone cable, and remove the plugpack
power supply. The power derived from the Cue King is 12V regulated and has the
effect of adding stability to the output section of the RF Receiver. It also
blocks anything coming back up the power line. We have not heard of anybody
having this issue when connected in this way.
- Change the plugpack to a regulated 12VDC model. (see
fix #1)
- Move the RF Receiver away from the source of noise. If
the wanted signal is larger than the unwanted noise, then the signal wins. How
far? Sometimes 1 Metre, sometimes quite a bit, depending on how prolific is
the offender. Sometimes it may be easier to put the RF Receiver down at the
stage, and run a mic lead back to your Mighty Rat. The length of this cable
run is generally not an issue. Keep in mind that the PC may be infecting the
power supply, and plugging into a new circuit may be necessary.
- If you have experienced this issue or are concerned
about it, there is a quick and inexpensive factory modification available
which renders the receivers immune to this kind of in-band noise. It is
recommended that you contact Szikla Technical and quote your receiver's serial
number to see if it qualifies. Units purchased after February 2006 feature
this modification as standard.
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