Dynon Skyview Classic, ADAHRS Module

[skippydiesel]

Having a bad trot with my ADAHRS. Wondering if anyone else in Au experiencing similar.

 

Original (first) module worked perfectly for aproximately 130 hrs
Failed without warning, on ground, on pre engine start check.

Cable continuity checked and found to be good.
Loan module worked perfectly for about 5 hrs - Replaced, still working, when new (not remanufactured) module arrived.

No explanation from Dynon as to reason for OM failure.
New module had initial problems (frozen compass) - Fixed by belated download/update
New module worked faultlessly for about 4 hrs
New module failed on ground, on pre engine start check. 
Dynon sending a loaner module, hope to install today

Note:
First module failure , turned whole electrical system off several times - red cross & failure message appeared each time

Second module failure, as above, however each time normal screen appears but only remains for about 30 seconds, before reverting to red cross & failure message. 😈

[rodgerc]

Might be worth chatting to David Brown in Brisbane. 
 

david at candoitaustralia dot com dot au

[skippydiesel]

Thanks Rodgerc - have emailed him😈

Edited March 24 by skippydiesel

[skippydiesel]

3 hours ago, rodgerc said:

Might be worth chatting to David Brown in Brisbane. 
 

david at candoitaustralia dot com dot au

Email address not good - got another?😈

[KRviator]

What's the failure message? That "Multiple Sensors failed" type thing can often be caused by attempting to do a pitot-static check without being in test mode, the ADAHRS sees the rapid climb/descent and IAS changes without corresponding GPS position or accelerometer changes and cries foul. Doesn't sound like you've actually done a P-S test, but it might be somewhere to start. First thing I'd do is unplug your GPS antenna, do a network calibration to rediscover all the modules but without the GPS, cycle power and see what happens.

[rodgerc]

3 hours ago, skippydiesel said:

Email address not good - got another?😈

Sent you a message 

[skippydiesel]

Had a great chat with David Brown - certainly knows his Dynon (& other) systems inside out.😈

[skippydiesel]

Latest ADAHRS fitted - off to the airfield to do the compass calibrations.

[skippydiesel]

Done!

Compass ground & air calibrations - 127%✔️

A of A also done but need to consult on when low speed warning comes on - currently at 50%😈

[skippydiesel]

ADAHRS out again - same symptoms as before - worked perfectly on last flight, turn system on, screen comes up normally for about 30 seconds , red cross comes up, ADAHRS sensors failed..

 

This time did a "forced load" - ADAHRS back as if nothing had happened???????

 

Have written to Dynon/Horsham - won't hear back until Monday

 

Any of the electronics "wiss kids" got any suggestions/answers😈

[Underwood]

Maybe the Dynon instrument itself has a problem (vibration/heat buildup?)

I'm chasing multiple problems with an MGL unit right now and its a nightmare.

[3rd harmonic]

Hi Skip,

 It would appear logically that after multiple different units being installed/uninstalled the original issue may not have been resolved...

I would be looking specifically at the grounding and or negative return to the battery.

Some bits of gear will do all kinds of funny things when the ground is lost, intermittent or high impedance.

If the main ground which is on the DB37 connector (I think) is faulty then current may be making its way back via the shields on the data Comms connections causing corrupted data.

A 4-wire ohm meter is the weapon of choice to do this that can accurately measure fractions of an Ohm (egg 0.01)

Check the plug, pins and crimps.

With the plug disconnected and no power applied, check the resistance back to the battery.

Aggravate, vibrate, tap things while doing these resistance checks

If the resistance changes or goes higher than 0.5 ohms then that could cause those issues...

It's a bit hard to explain exactly how to go about this, but hopefully that gives you some idea...

[sfGnome]

1 minute ago, 3rd harmonic said:

Aggravate, vibrate, tap things

An engineer’s most important tool - aka ‘percussive maintenance’. 

[onetrack]

Faulty connections, corroded connections, damaged plugs and connectors, these are all the nightmares of electrical/electronic trouble-shooting, and they can take a long time to pin down. It's a steady process of elimination.

[facthunter]

Cannon Plugs etc.  Have to be made of the right stuff. . Nev

[3rd harmonic]

I have seen D connectors where the pin has been pushed back into the plug. In my context that is 8 channels of balanced audio on a DB25 using the TASCAM pinout - a faulty pin can result in losing half or 6dB of the signal, either the +hot or -cold.

Looking at the Dynon installation manual and DB37 connector pinout there are 2x V+ power inputs (pins 1 and 20) and 4x ground pins (pins 21, 22, 23 and 24) for redundancy.

Power and ground are right next to each other and the pins are also pretty close inside D connectors and it is very easy for even a single strand to come adrift and create an intermittent short circuit which could easily generate the funny resets ect

I would open up the back shell on the DB37 plug and check that as a first port of call...

[skippydiesel]

Dynon have asked me to;

• Disconnect the ADAHRS
• Check pin 2 & 7
• Report finding to 1/0 of an ohm