SKYVIEW Internal Voltage FAIL

[umair2203]

Dear concerned,
we have installed your Sky view system on our aircraft. It flew fine for first two sorties. On third engine start up, one of the them displayed message of "Interval voltages Fail 12V" in local screen set up in hardware information. Now it does not gets tuned on. Power is being supplied to MFD (as its back fans are running but no display). It also has back up battery installed on it. But the display is not coming on. Please respond as how to troubleshoot "Internal Voltages Fail 12V", what does it mean? and how to troubleshoot it.
Please reply as soon as possible
Regards
Umair

 

[umair2203]

The display turns on for some time now ... when you go into the hardware screen set up you see the internal battery is discharging fast and it displays "Internal Voltage fail 12V"

HOWEVER BACKUP BATTERY RUNS FINE ON OTHER DISPLAY !

 

[dynonsupport]

Please contact our Technical Support staff at support@dynonavionics.com, or +1-425-402-0433.

 

[umair2203]

I called ! nobody responded ! may be because of weekend. I need it urgent

 

[dynonsupport]

We are closed due to the weekend.

12V can mean it's not getting external power. It will say that any time it's running on battery. Are you sure that the breaker/fuse is still OK, and that all your wiring is good?

The same page shows mater voltage coming in to the unit. Is that reading right?

 

[umair2203]

yes those are right. exactly right rather. (24V). I connected second display to the same plug it is working fine so the problem is with in display it self. wiring and plug all okay

 

[schristo]

do you have back up batteries on both displays? it sure sounds like one display is not getting power and ran down the battery... you indicated that you plugged the other display in and it worked but did you unplug the battery back up during the test?

 

[umair2203]

I connected the back up battery to second display.. its status was charging (around 10.5V) but on second display (faulty one) battery gets discharged on a very fast pace (display shuts down in 5 to 10 second) and it reads "Internal voltages fail 12V"
What actually happened was during engine start up some one mistakenly removed the external power while main alternator was not on and then again plugged in the power. both display grew white and shut down. After that one display was back on but other wasn't.

 

[umair2203]

and yes i unplugged the battery. One display is working and other is not (it powers on while battery connected for 5 to 10 seconds)

 

[dynonsupport]

It sounds like whatever happened to the display damaged the power supply so now it can only run off battery. It is likely that you exceeded the 30V rating of the SkyView. You will need to contact us on Monday so we can arrange a repair. There is nothing you can do to fix this.

 

[vlittle]

It sounds like whatever happened to the display damaged the power supply so now it can only run off battery. It is likely that you exceeded the 30V rating of the SkyView. You will need to contact us on Monday so we can arrange a repair. There is nothing you can do to fix this.

My experience with Avionics is that customers often exceed "do not exceed" voltages. At one time, I had failures with circuits that would operate up to 16V, so 12/14V systems would be ok, right?

Not so, because customers had a habit of testing devices on the ground with questionable power sources (battery charges and so on), which were poorly regulated.

I guess what I'm saying is that a 30V maximum for a 28V system is probably not enough margin for error, and even in flight a misbehaving regulator can cause the bus to exceed this voltage.

It's tough to build external crowbars or voltage clamps that are accurate to within a volt over temperature and time, so my feeling is that an external regulator would be wise.

Vern

 

[umair2203]

at ground run the electrical technician accidently removed the power (while engine was in starting phase and alternator was not on) thne he quickly plugged back the power. was it due to power surge ??

 

[dynonsupport]

Vern, the system is designed to meet the RTCA DO-160B specs for a 28V piston plane. It can handle 45V for a long time and 60V for 100mS. We did design in quite a bit of margin, and we did test to the certification standards.

We've also seen 28V planes that put 200V on the system when the master contractor opens up. That's a lot of margin, and we don't have quite that much as the customers helped us discover

Clearly in this case, something very nasty happened when the power was pulled during engine start. This sounds like a turbine and the starter/generator probably backpowered the system to quite a high voltage somehow. We'll get it fixed for the customer.

 

[umair2203]

Thank you Dynon support. I have messaged u privately my contact. Our vendor through which we bought will be in contact shortly. We want it replaced as repairing it and then sending it back to Pakistan will waste precious time. We are looking to change our whole fleet with Sky view and we hope a positive cooperation from you which still now looks good

 

[umair2203]

I want to know why it happened. Why didn't Circuit breakers pop out if there was some nasty surge ????

 

[umair2203]

Vern, the system is designed to meet the RTCA DO-160B specs for a 28V piston plane. It can handle 45V for a long time and 60V for 100mS. We did design in quite a bit of margin, and we did test to the certification standards.

We've also seen 28V planes that put 200V on the system when the master contractor opens up. That's a lot of margin, and we don't have quite that much as the customers helped us discover

Clearly in this case, something very nasty happened when the power was pulled during engine start. This sounds like a turbine and the starter/generator probably backpowered the system to quite a high voltage somehow. We'll get it fixed for the customer.

Why didn't circuit breakers pop out. ??? They are working fine

 

[dynonsupport]

Circuit breakers are there to protect wires, not devices. The only point of a circuit breaker is to prevent a fire. They are slow and cannot protect from a fast voltage surge, nor does a fast voltage surge mean that the current has gone up. In fact, in many circuits, higher voltage means lower current.