Rare problem with D-100/D-180/HS34 system

[johndavies]

I now have 50 hours on my RV-7A with the above Dynon components with an SL-30/GNC-300/GPS296 connected. Everything has worked perfectly as advertised but I have run across a perplexing problem. Three times I have made a flight and stopped for lunch and left the plane parked on a warm day (but this is Canada so not HOT). After lunch the HS34 will not come on (I get the DSAB lost alarm and on checking there are no lights on the HS34) I reboot, cycle the master etc, whatever I do nothing happens. NOTE This is BEFORE cranking the engine. The D-100/D180 work perfectly and I come home with just the "redundent safety wired" 296 driving the HSI. I put the plane away and lo, the HS34 works perfectly and the problem cannot be duplicated. I have pretty well ruled out the obvious (a loose power connection) - the problem never happens except during these exact circumstances. I suspected low voltage maybe (the D100 and D180 have battery backups) but cannot duplicate with low voltage. I thought maybe software so have upgraded all three units to Ver 5.3. My question is; has anybody else had this problem? Is there maybe a temperature cutout on the HS34? Is there some form of software time delay after a DSAB loss that prevents rebooting until some time has past? Is there any known HS34 power supply problem? Am I right in thinking that the HS34 lights come on whenever there is power to the unit or is there any circumstance where a lost DSAB can prevent the lights coming on for a while? Any help would be appreciated.
Thanks, John

 

[Brantel]

Pierre over on the VAF forum had a problem with his HS34 and heat as well. Looks like a trend is developing....

He called Dynon and they tested one in their heat box and swapped em out.

Give em a call, they will fix you up.

 

[johndavies]

Thanks for the advice. We have our first hot weather of the summer here in BC and today I was able to reliably recreate the problem. By repeatedly wheeling the plane out into the sun, leaving it until the temperature inside got beyond 85 degrees F, and then wheeling it back into the hanger to cool, I proved that the HS34 ceases to power on at these higher temps. When it cools it does not come on by itself (which is why I did not get it back online for the flights home as the plane interior cooled down) but it comes back on when the power is recycled (once the interior cools below 80 degrees or so) I managed to recreate this cycle three times so have reasonable confidence in the diagnosis (as well as getting hot and sweaty!). So I guess its an RMA for me.
Thanks, John

 

[dynonsupport]

There have been a few of you that have mentioned problems like this, so we are looking into it. Nothing to report just yet though.

 

[lindsayj]

I have the same problem in my RV-8A with D10A and 2 servs. Has happened about 3 times this summer. After the second time I went thoroughly through the wiring and made an adjustment on the ground at pin #17. Seemed to have solved the problem until yesterday when the HS34 did not come on line at a fuel stop with outside temp about 93 degrees. I returned home without HS34 inputs and AP. Not good for confidence if you're working IFR. I could not recycle the unit until this AM. Glad to see I'm not alone. I'll call in to tech support to see about a swap...Jack L.

 

[rvg8tor]

Was a solution ever found for this heat issue, I bought my HS34 two years ago and just now getting the panel wires up, wonder if I should return it or put some insulation around the unit.

Thanks

 

[dynonsupport]

A small percentage of HS34s were more heat sensitive than they should have been. We've systemically fixed this in units newer than yours, but on older HS34s we fix them as problems are reported since it's a pretty rare issue. Basically, if your unit is affected, it may stop working properly in the high 40s Celsius range. Below those temperatures, it will work normally. So you can "wait and see' if your unit is temperature sensitive, or alternatively, give us a call for an RMA and we're happy to fix it pre-emptively.

Definitely don't insulate the unit itself in any way: you won't keep a sun-soaked airplane from transporting heat into the HS34, but you could keep it from cooling off quickly after flying cools off the panel adequately.

 

[Bo_Hannington]

I have an HS34 in my aircraft and I also have had intermittent problems on power-up.
Until I read these posts today, I had not related my problems to temperature.
I originally thought the problem was a poor connection or a momentary low voltage during start-up which would prevent the HS34 from booting properly. Recently I have been very careful to make sure everything is up & running, engine running and charging etc etc before powering up the HS34 & I thought the issue was solved.
But I had the problem again 2 days ago when I started up to fly 2 hours home, and had to do without the autopilot or audio messages all the way home.
The problem has only ever occurred during power-up, never when it is operating. When it fails to start, I get the network error message after a few moments, and also no lights of any kind on the HS34.
Is this the same problem?
If so, Mr Dynon, can I get my HS34 replaced.
Bo Hannington

 

[dynonsupport]

Please give tech support a call at 425-402-0433 or an email at support at dynonavionics dot com.