Your unit will be repaired, tested, and returned to you with a new crystal of a different part# than the original. The new crystal has gold plated contacts for a better solder weldment and improved overall characteristics.The part number for the new crystal is (Abracon Corporation) ABM7-16.000MHZ-D-2-Y-T, or digikey# 535-9840-1-ND, it is a 16MHz 18pF quartz crystal with a footprint size of 0.236" L x 0.138" W (6.00mm x 3.50mm). PLEASE be sure to tell us the serial number of your unit if you self-service so that we can track outstanding recall units. Thank you!
There is no time limit for this recall. Although, we urge you to return your unit for repair immediately. Servicing and recertification is available to anyone with a V1E regardless of the original ownership, just send it to us no questions asked.
It has been discovered that it is possible for a dying crystal to cause the motors to throttle up even while the copter is in the "disarmed" state. Though this is a rare occurance, it has been reported and recently deduced to be caused by failure of the quartz crystal. We've tracked an unusually high number of warranty returns with faulty crystals and up to now were happy to handle each as a warranty issue. However, in light of new evidence regarding the safety of a faulty crystal we feel obligated to recall all units with this part#.
See What Went Wrong? at the bottom of this text for more information on the risks concerned in this recall.
Our contact information is listed on the Recall form. You may also speak to us during our regular weekly webex meeting on Sundays.
We recommend that you return your unit to us for the proper servicing procedure. Though given the technical nature of many of our customers, under some circumstances we may grant the user (you) to service thier own unit and we can ship the replacement crystal to you. Performing the desoldering of the old crystal and soldering of the new one does require a competent level of soldering experience to be done properly. Recommended tools and supplies would be a soldering iron capable of surface mount soldering, hot-air or infrared reflow tool, small gauge high-quality solder and flux. The repair is further complicated by the conformal coating that protects the boards. If not done carefully the conformal coating may become marred making the repair visually unappealing (but otherwise fine). If you have surface mount soldering experience and feel you can do the repair yourself contact us using the information in the Recall form to discuss further.
Send your unit(s) and recall form to one of these addresses:
United States or International
11242 Kapok Grand Cir
Madeira Beach, Florida
c/o Schooner Solutions Inc
217 St George Blvd
Hammonds Plains, Nova Scotia
Canada, B4B 1K7
The crystal on the Quadrino is the basis for the timing of all systems within the flight controller including the timing of the motor output PWM signals. This is common of all RC flight controllers. In most circumstances quartz crystals are a very reliable source of timing. Quartz crystal are found in many electronic devices, including your computer, laptop, PDAs and even your wrist watch. It is a piezo-electric based device which, in simple terms, is the electrical equivelent of an elastic and a transducer (speaker). When a signal is applied to the crystal it vibrates at a resonant frequency just as an elastic would vibrate if exposed to the proper sound, in our case the crystal vibrates at 16MHz or 16 million times per second.
In most cases, these dying crystals die completely and instantly which results in a completely unresponsive unit. This is a good thing! In some rarer instances as the crystal is dying it appears to "slow down", meaning instead of outputting the constant 16MHz signal it drop down to 15MHz, 13, 12, 10, 5, ....then stops. If we turn off the sound on our vibrating elastic, the elastic continues to vibrate for a very short time afterwards but quickly slows down until it eventually comes to a complete stop. The quartz crystal can have the same effect. It is this slowing down of the crystal that poses the greatest risk.
As mentioned earlier, the crystal is the basis for all timing on the controller. As the crystal slows down, it slows down the controller's microprocessor and the system that controls the PWM motor output. This has an effect of stretching out the signal. Think of workers working under tight deadlines. As the workers slow down, thier deadlines naturally begin to stretch out. PWM motor signals are all about timing. The PWM signal is an ON or OFF signal where the ON time is measured between 1000 and 2000 microseconds (usec). A 1000 usecs of ON time tells the motors to stay disarmed, whereas an ON time of between ~1250 and 2000 usecs tell the motor to throttle between idle speed and full throttle, respectively. Flight controller's must send a minumum of 1000 usec at all times or else the motor/ESC will enter a power-down state and continuously beep (typical case). In the case of a crystal whose frequency is slowing down this 1000 usec signal (disarm command) is stretching out into the 1250 and beyond range which is causing the copter to throttle up unexpectedly. The crystal will completely fail within a few seconds but in those few seconds an out of control copter could cause significant damage or injury. For this reason, it is imperative that a recall on this crystal part# is done even if the unit has been operating normally all this time.
Sometimes the most innocuous thing can come back to bite you! Dave Jones of EEVblog explains a very costly mistake he encountered while working for one of his past employers. Excellent story!