What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

GRT HX boot problem

gerrychuck

Well Known Member
I just installed/had installed a 6.5" GRT HX in my 6A with a wiring harness from Stein. Works well, although I need to get back into the aft fuselage to shim the AHRS as it shows a 3.5 degree bank with the ball correspondingly off center. Oops, guess my homemade mount wasn't quite as level as I thought!

But I digress. The reason for this post is that the HX seems more than a little finicky about booting. Currently it is wired straight to the master, so it gets power as soon as the master is turned on (that will likely be changed, either wiring it to the separate radio master or a toggle switch). At any rate, it rarely boots successfully on the first try, either with or without an engine start. The first time I flew with the unit, it didn't boot, so after engine start I flipped the master off for a few seconds, flipped it back on again, and that time the unit successfully loaded. Tried the same again today, and repeated the process several times on the ground without success. Tried again a couple of times in the air; still no luck (I still have my original ASI and altimeter in the panel). Back on the ground, in the hangar, I flipped the master on and it booted right up. The tech that did the final wiring said that it may be very sensitive to voltage drop, and that made sense in the hangar, where I had much better luck if the battery was kept connected to maintainer, but today it was refusing to boot after the engine and alternator were operating, showing 14.5 volts. When it did boot, it was sitting on the hangar floor showing 12.5v. The only other variable I can think that could be involved is temperature; most of my failure to boot episodes were in the hangar at about 50 degrees F, but when it did boot today I had been working in the hangar for a couple of hours and had the temp at over 60. That doesn't explain the variability in booting up with the engine running outside, however, where the temps were below freezing both when it worked and when it didn't. Admittedly, colder today than the last time when it agreed to power up, but much colder than in the hangar on both occasions.

I will probably end up contacting GRT to get their wisdom, but thought I'd run this by the braintrust here first. I also need to contact the avionics tech again to see exactly what breaker he wired the unit to on the power bus. I'm quite puzzled at this point, and appreciate any thoughts or advice. Thanks in advance.
 
GRT boot issue

When it does not boot, what do you see on the screen? Mine is a Sport, and has never failed to boot. But it does have a period of not showing anything or just showing text. I've got an EarthX along with a TCW Tech backup battery that I keep fairly well maintained.

I would double check the wiring and of course in particular the grounds. It sounds like it's not getting consistent power. Fully realize this is not as easy to do as it is to write. Good luck, and please let us know what you find.
 
GRT HX Boot

If you don't have a backup battery (or something like the TCW power stabilizer) connected to one of the GRT's backup power inputs for keeping the GRT powered when you start the engine then you should have it powered from the avionics master switch and power it on after starting the engine. Pretty much guaranteed, on engine start, the battery voltage is going to droop below the level for the GRT to operate and it will reset (just like most all of your other avionics will do). It's just more obvious on the GRT because it takes 10 or 20 seconds to complete its power up sequence.

Assuming you have the GRT EIS, it operates very nicely (not affected by the drooping battery voltage) during engine start so you can monitor oil press, RPM etc. on it while waiting for the Hx to power up after starting the engine.
 
Gerry - a couple of thoughts...
1) the HX takes time to boot, longer than you would expect
2) when it is booting don't touch it... if it last was at a dim setting, touching a button within the first 8 seconds of boot will allow that dim setting to be the setting used, thus your screen may be on but so dim you can't see it. Leaving the boot process run unmolested is the best way to ensure the box comes up at full brightness
3) each power input (there are 3 on the HX) goes through an isolation diode inside the box, thus you can have multiple power inputs connected to the box while keeping them fully isolated
4) try one of those other power inputs - that means moving the pin in the connector, which is a quick and easy troubleshooting step.

I've found the HX does not like to come back after an engine start brown-out. I run mine on an Essential bus that has its own battery, thus it doesn't get browned out during startup. Also, be aware that starting the unit in cold temperatures means the backlight heaters will be on full blast, increasing current consumption. This will mean that any wiring errors like a high resistance power connection.will be exacerbated by low temperature starts.
 
HX Boot problem

I had this same problem on mine and it turned out to be the supplied memory stick became "corrupted" and prevented a good boot. Took it out and all was well. Tried a new one for a while then it happened again. Now I just install the stick when I'm updating the database but don't leave it in all the time. No problems since.
 
I had this same problem on mine and it turned out to be the supplied memory stick became "corrupted" and prevented a good boot. Took it out and all was well. Tried a new one for a while then it happened again. Now I just install the stick when I'm updating the database but don't leave it in all the time. No problems since.

Ohhhh now that's a good point! I wouldn't naturally have thought of that but I do leave memory sticks in place permanently. Thanks for the good tip!
 
When it does not boot, what do you see on the screen? Mine is a Sport, and has never failed to boot. But it does have a period of not showing anything or just showing text. I've got an EarthX along with a TCW Tech backup battery that I keep fairly well maintained.

I would double check the wiring and of course in particular the grounds. It sounds like it's not getting consistent power. Fully realize this is not as easy to do as it is to write. Good luck, and please let us know what you find.

Nothing on the screen; once the text shows up, it's on it's way and boots successfully. There will be a brief flash of the backlight when the power comes on, then an essentially black screen (I say essentially because there is usually a hint of light from the backlight)

If you don't have a backup battery (or something like the TCW power stabilizer) connected to one of the GRT's backup power inputs for keeping the GRT powered when you start the engine then you should have it powered from the avionics master switch and power it on after starting the engine. Pretty much guaranteed, on engine start, the battery voltage is going to droop below the level for the GRT to operate and it will reset (just like most all of your other avionics will do). It's just more obvious on the GRT because it takes 10 or 20 seconds to complete its power up sequence.

Assuming you have the GRT EIS, it operates very nicely (not affected by the drooping battery voltage) during engine start so you can monitor oil press, RPM etc. on it while waiting for the Hx to power up after starting the engine.

No backup battery, but booting the HX with a battery minder attached has invariably resulted in a clean startup. I completely agree re: having the unit on the avionics master, and don't know why the tech didn't do that in the first place. He also had a wired toggle switch available that powered the electric AI that the HX replaced; I assumed he would simply use that power supply without modification for the EFIS, but apparently I didn't specify it, and then I was out of the country when he was doing the actual work, and he removed the switch and wired the HX in on the main master. Faulty assumptions; that's on me.

Gerry - a couple of thoughts...
1) the HX takes time to boot, longer than you would expect
2) when it is booting don't touch it... if it last was at a dim setting, touching a button within the first 8 seconds of boot will allow that dim setting to be the setting used, thus your screen may be on but so dim you can't see it. Leaving the boot process run unmolested is the best way to ensure the box comes up at full brightness
3) each power input (there are 3 on the HX) goes through an isolation diode inside the box, thus you can have multiple power inputs connected to the box while keeping them fully isolated
4) try one of those other power inputs - that means moving the pin in the connector, which is a quick and easy troubleshooting step.

I've found the HX does not like to come back after an engine start brown-out. I run mine on an Essential bus that has its own battery, thus it doesn't get browned out during startup. Also, be aware that starting the unit in cold temperatures means the backlight heaters will be on full blast, increasing current consumption. This will mean that any wiring errors like a high resistance power connection.will be exacerbated by low temperature starts.

Some definite insights here. I do know the unit takes time to boot, and always have waited much longer than it ever takes when it actually fires up. Good advice nevertheless, as many of us can be a wee bit impatient when we want to get airborne.

Did not know that about the 3 power inputs; might be worth a try

The backlight heater power consumption could well be a factor, and one I was unaware of; I have consistently had more reliable boots with warmer temps. Here's a thought; I could stick my little heater I used to use for preheat (before the luxury of a heated hangar) inside the cockpit before startup to prewarm the instruments. Ultimately, of course, I need to switch the wiring to a switch or to the avionics bus.

I had this same problem on mine and it turned out to be the supplied memory stick became "corrupted" and prevented a good boot. Took it out and all was well. Tried a new one for a while then it happened again. Now I just install the stick when I'm updating the database but don't leave it in all the time. No problems since.

I know the tech updated the software, but I don't believe he left the stick attached; I have a bluetooth dongle in one USB port, and the other wired to a port on the panel, which has nothing attached. I believe there are just two?

Thanks so much for all the input so far; very helpful. First order of business is to get the wiring separated from the main master bus. That is clearly needed above all else.
 
Gerry - just a thought...

You wonder why the installation tech would not have wired the HX to the Avionics Master. That's because GRT's installation manual expresses a preference for the EFIS to be wired to the main bus such that it comes on any time the master is turned on.

If we think of this in terms of failure scenarios, with the HX wired to the avionics master, first the Master has to be turned on (and work), then the Avionics Master has to come on (and work). That doubles the number of switching points that have to work before you have a viable primary flight instrument. For this reason many aircraft are wired so the glass powers up with the aircraft master. The added bonus is that turning off the avionics master by accident (search posts on this forum, you'll see it has happened more than once!) won't result in the loss of primary flight instruments if the EFIS is wired to the main bus.

Ultimately the best solution is to have the EFIS wired to the main bus AND some form of backup power which prevents the EFIS from being "browned out" during engine cranking.

At this point I'm going to split my bets 50/50... One half of me says there's a resistive connection somewhere in the power input circuit (likely at the circuit breaker or the HX connector). The other half is laying its money on the HX having suffered an internal failure. Given my experience with wiring errors, I'm thinking I should be making this maybe a 70/30 bet in favor of too much voltage drop between the battery and the HX.
 
The install manual for my HX, which I?m still installing, says if your HX EFIS is powered off the same battery that you use to start your engine, you should install a switch to power the HX so you can have it turned off during engine start. It also says that the HX (10.1 in my case) draws less then 2 amps, and a small backup battery to power a secondary power feed to the HX during engine start would allow you to keep it powered from the start without suffering the brown out scenario. There is also a third power feed channel for if you have a second alternator/bus system or third battery. I only have two, so that?s what I am using.
 
Thanks to both of you for those insights. As I mentioned earlier, there was a switched power supply (off the main bus) just waiting to be transferred from the electric AI to the EFIS. I had intended to do it that way for the reasons you have outlined, but I was in Europe when the tech showed up and did the work and it didn't happen that way. Sigh. Best laid plans. Get that switch put back in, check the wiring path, and go from there. I need to find out what circuit breaker the HX is on; I am wondering if it is on the same one as the Digiflight II AP, which has been acting a bit funny since the efis install as well (the display starts out very dim on startup, then brightens partway into the flight, and sometimes flickers between normal brightness and dim; never did that before) which makes me wonder if there is too much draw on that circuit. Breaker hasn't tripped, but these two units don't seem happy. Actually, that gives me an idea; the AP has it's own toggle switch on the panel; in the short term I could switch the AP off until the HX boots to reduce the draw (if they're on the same circuit), then power the AP up afterward. Worth a try.
 
Thanks to both of you for those insights. As I mentioned earlier, there was a switched power supply (off the main bus) just waiting to be transferred from the electric AI to the EFIS. I had intended to do it that way for the reasons you have outlined, but I was in Europe when the tech showed up and did the work and it didn't happen that way. Sigh. Best laid plans. Get that switch put back in, check the wiring path, and go from there. I need to find out what circuit breaker the HX is on; I am wondering if it is on the same one as the Digiflight II AP, which has been acting a bit funny since the efis install as well (the display starts out very dim on startup, then brightens partway into the flight, and sometimes flickers between normal brightness and dim; never did that before) which makes me wonder if there is too much draw on that circuit. Breaker hasn't tripped, but these two units don't seem happy. Actually, that gives me an idea; the AP has it's own toggle switch on the panel; in the short term I could switch the AP off until the HX boots to reduce the draw (if they're on the same circuit), then power the AP up afterward. Worth a try.
 
serious wiring problem

... Get that switch put back in, check the wiring path, and go from there. I need to find out what circuit breaker the HX is on; I am wondering if it is on the same one as the Digiflight II AP, which has been acting a bit funny since the efis install as well (the display starts out very dim on startup, then brightens partway into the flight, and sometimes flickers between normal brightness and dim; never did that before)..
This definitely points to a wiring issue. I know it's a pain, but I'd get this fixed before flying or you might find some of that magic smoke escaping from the wires.
 
Ummm... I'm going to sound like an old curmudgeon here and I make no apologies for it.

If you had a tech install the HX and he did so in a manner which leaves you not knowing which CB is powering the HX, FIRE THE TECH and don't ever let him touch your airplane again!

Every CB should be labelled and you should easily be able to tell which breaker you have to pull to stop smoke coming from a device. Failure to properly label the CB and to properly annotate the installation/wiring diagram for the aircraft is exceptionally poor workmanship.

As others have noted, installing a small backup battery is a great way to make sure your HX doesn't get browned out during cranking. It can be a very small battery indeed, charged through a diode from a CB on the main bus. The output of the battery could go to the second or third power input on the HX and on the AHARS (both need to be powered, and GRT recommends they are powered through separate CBs).

A battery like this one would work just fine.
https://www.amazon.ca/Discover-Seal...ords=12V+2.5ah+battery&qid=1578015731&sr=8-35
 
power stabilizer

...

As others have noted, installing a small backup battery is a great way to make sure your HX doesn't get browned out during cranking. ...
I used the TCW Technologies IBBS, but if I were to do it today, I'd use their "power stabilizer" https://www.tcwtech.com/IPS-12v.htm

This would solve the brownout at engine start issue, with a very simple installation, no charging, less maintenance, etc.
 
I used the TCW Technologies IBBS, but if I were to do it today, I'd use their "power stabilizer" https://www.tcwtech.com/IPS-12v.htm

This would solve the brownout at engine start issue, with a very simple installation, no charging, less maintenance, etc.

I have the TCW power stabilizer installed. Dead simple installation, weighs almost nothing, never needs recharging or replacement and works as advertised. Not sure why it?s not more popular.

Erich
 
This definitely points to a wiring issue. I know it's a pain, but I'd get this fixed before flying or you might find some of that magic smoke escaping from the wires.

Plane is currently down for annual, and that is definitely my intent

Ummm... I'm going to sound like an old curmudgeon here and I make no apologies for it.

If you had a tech install the HX and he did so in a manner which leaves you not knowing which CB is powering the HX, FIRE THE TECH and don't ever let him touch your airplane again!

Every CB should be labelled and you should easily be able to tell which breaker you have to pull to stop smoke coming from a device. Failure to properly label the CB and to properly annotate the installation/wiring diagram for the aircraft is exceptionally poor workmanship.

As others have noted, installing a small backup battery is a great way to make sure your HX doesn't get browned out during cranking. It can be a very small battery indeed, charged through a diode from a CB on the main bus. The output of the battery could go to the second or third power input on the HX and on the AHARS (both need to be powered, and GRT recommends they are powered through separate CBs).

A battery like this one would work just fine.
https://www.amazon.ca/Discover-Seal...ords=12V+2.5ah+battery&qid=1578015731&sr=8-35

In the tech's defence, he does not consider the job finished; he has planned all along to return to reswing the magnetometer and finish up the details, and as soon as I contacted him about the boot issues he wanted to replace the switch and do a battery load analysis at the same time. He travels from Regina (40 minutes) and has been very apologetic he hasn't been able to schedule that final visit yet. Don't worry about being a curmudgeon; I like curmudgeons. I appreciate all the advice. The battery is definitely worth consideration as well.

The power stabilizer looks like a great idea, and I suspect your analysis of the reason for it not being more popular may be correct.

Quick related question; as a Canadian with GRT glass, are you using the Jepp database, and what is it costing you?
 
Glad to hear you're continuing to work toward perfection in this installation, Gerry.

To answer your question, yes, I've been using Jepp data. I can't remember the cost precisely but I want to say something like CAD$200. Sorry, I just can't remember what I paid last time.

In truth, I tend to rely much more on my tablet for chart data and I have an IFR GPS navigator so keeping the GRT updated isn't my very highest priority. My subscription lapsed in the fall and I just haven't got around to renewing it yet this year.
 
I have the 4 amp TCW power stabilizer installed. $265.0 at Aircraft Spruce. Keeps two Hx displays and a dual ADAHRS powered up during engine starts.

I originally had a TCW backup lithium battery but it has an of/off switch, so it has to be enabled before engine start and disabled after shut down. Managed to leave it enabled for a week or so and discharged it to the point it wouldn't recover on its on. Had to send it back to TCW to get it repaired. Decided the stabilizer was a better solution for me as it requires no operator actions, doesn't need to be charged periodically or tested each condition inspection etc. it just does its thing and keeps everything powered up during starts.
 
In truth, I tend to rely much more on my tablet for chart data and I have an IFR GPS navigator so keeping the GRT updated isn't my very highest priority. My subscription lapsed in the fall and I just haven't got around to renewing it yet this year.

Likewise. I very rarely update the database for my aged KMD 150, and rely on updated charts from Fltplan Go for currency. Since my used HX came from the US, however, I need to get a Canadian database just to make the unit useful driving the autopilot. I suspect I will be reluctant to keep it up to date, but on the other hand I doubt it will cost the absolutely criminal amount that the KMD costs to update.
 
In truth, I tend to rely much more on my tablet for chart data and I have an IFR GPS navigator so keeping the GRT updated isn't my very highest priority. My subscription lapsed in the fall and I just haven't got around to renewing it yet this year.

Likewise. I very rarely update the database for my aged KMD 150, and rely on updated charts from Fltplan Go for currency. Since my used HX came from the US, however, I need to get a Canadian database just to make the unit useful driving the autopilot. I suspect I will be reluctant to keep it up to date, but on the other hand I doubt it will cost the absolutely criminal amount that the KMD costs to update.
 
Back
Top