Voyager going crazy. Airspeed, Altitude and Voltage

[JimJab]

Hi All,

Well, can someone put some light on what is happening, one of my Voyagers is going crazy, it boots fine, but it's reading are not right.

On my second last flight, I notice this Voyager's Master Voltage and Back-up Voltage meters after boot up read very lower and then later in the flight, the voltages read similar to the pilot EFIS voltages.

Then on boot up for my last flight this EFIS showed similar voltages a again, but also had an airspeed when I was still stationary and the Altimeter compared to the other EFIS was not reading the same with the same QNH. After take off I notice the airspeed was reading correctly.

It was only about 4 flight hour ago that both EFISs had their checks done for airspeed and altimeter and both were found with in limits.

Today having the chance, I put this EFIS on the bench, to test the EFIS without anything else connected to it other than the DC power supply. The Master Voltage and Back-up Voltage Meters started off reading 4.8v and 5.0v, both voltage readings slowly climb over a 20-30 minute period until they read 12.9v and 13.7v, with the DC power supply to the EFIS remaining between 12v to 11.5v. during that time.

I did check the voltage at the Emergency Supply Back-up Battery terminals with a multimeter this voltage was reading around 10.5 volts, I thought it would have read the same as the supply voltage to the EFIS.

Whilst doing the bench test on the EFIS's voltage, I booted the EFIS several times and the airspeed remained somewhere between 154 to 200 kots.

Does anyone make any sense of this?


Cheers
JimJab

[JimJab]

Well I am not sure if anyone else gets to this point where you just have one more issue and it makes you feel like you need to replace the whole glass panel, well that was where I was when posting this subject last night.

Well, it's a new day, so back to my electronics workbench and I fired up the EFIS for the upteen time to see exactly what the airspeed was doing. Yep, 154 knots and going nowhere and the voltage was reading low volts.

IMPORTANT WARNING

If you are going to poke around in your EFIS, make sure you know the different ways you can let the magic smoke out. Never open up your EFIS unless you have practice your electronic skills on something which is worth a lot less money.

So before before I fired up my EFIS, I flexed and put a little pressure on the solder joints around the airspeed sensor board. I then fired up the EFIS and noticed the airspeed value had changed, so the next easiest thing to do with the EFIS running was to move and flex the FFC cable going to the airspeed sensor board.

As I move this FFC cable from the airspeed board the airspeed was jumping up and down to zero, by holding the cable in one particular position, I could get the airspeed to remain on zero, moving this cable also cause the altimeter height to change and go wild.

Well all this put a smile on my dial, could it be that simple and replace the FFC cable, I had ordered some cables online a number of weeks back to replace all the FFC cables in both my EFIS.

So I pulled out the new FFC cables and found they sent me the wrong type (Type B or Reversing FFC cable), they will fit without issue. But if you use the wrong type you will be reversing the wires between the two sockets and by doing this, at best nothing will happen and at worst you may blow the Sh___ out of your EFIS.

So back online to order some more FFC cables for my Voyager, we need Type A or "Same" Cable, AWM 20624 80C 60V VW-1, 20 pin, 0.5 pitch and 200mm long. Be careful there seems to be a current world shortage of these A type FFC cables and maybe that is way I was sent the wrong type.

If you're wondering how can you tell the difference between the two types, it's easy, lie the ribbon on the table and if the wire conductors on each end are facing up, then is a Type A or "Same" Cable, now if you have a one end with the wire conductors facing down and the other end with the wire conductors facing up, it's a Type B or Reserving cable.


Cheers
JimJab

[PaulSS]

I do admire your persistence in this and your GPS snag. I wish you the best of luck resolving both and not rushing off to the Dynon shop

[JimJab]

I do admire your persistence in this and your GPS snag. I wish you the best of luck resolving both and not rushing off to the Dynon shop

Thanks Paul,for your comment about my persistence, I was close to losing it.

Dynon, I have not flown much behind them, I have flown behind a G1000 in Cessna 172 for a number of hours and I really prefer the MGL Voyagers over the G1000, putting aside the Voyager is not TSO approved.

If Rainier or some one else said they could supply me with a new Voyager or genuine refurbished Voyager, I would be more than happy to take it and drop it into my panel tomorrow.

Of all the problems I have encountered with my Voyager EFIS's, most of the issues to date have been mechanical type failures from 12 years of being in service and bumping around the sky and down rough runways.

The first issue I found after buying the plane, I noticed was my pilot EFIS skipping onto the Battery Back-up supply often, I finally found that the EFIS's DB-9 wires that powered the EFIS had broken internally from vibration and fatigued, so the internal positive wire would make and break the power from the main power supply.

But working through all these issues, I have found many have been from incorrect installation of wiring and and or sensors, like a major major problem I found was with my fuel tank gauges that were not earthed back to the RDAC earth, but incorrectly earthed to my instrument panel. This caused major issues causing all the engine monitoring gauges to be flakey and reading incorrectly.

The EGT and CHT sensors were reading, but way out of spec and some needed replacing. As I fixed one issue, I would then notice something else does not look quite right, so you then calibrate the EFIS via the menus and founded these setting could also be in-correct.

If I was someone who had fixed all these issues before with the MGL EFIS's, I am sure they could be fixed in 10 's of Hours and not in 100's of hours like I have spent.


Onwards and up we go.

Cheers
JimJab.

[mikeh]

Yes,
I second Pauls comments. Thanks for sharing with us all.
Cheers
Mike

[JimJab]

Yes,
I second Pauls comments. Thanks for sharing with us all.
Cheers
Mike

Thanks MIke for your kind thoughts.

Well, I am pretty excited today, I found a problem that could easily be causing many of my Voyager issues, like acting so crazy misreading the airspeed, altimeter heights and voltages, these just started playing up in my last hour of flight time. It may also explain why I could not get the AOA to work and OAT not reading right some time back.

Sadly, I don't think this has anything to do with my GPS issues.

I can't believe I did not do this when I had my EFIS on my workbench previously. But this time I removed all the EFIS FFC ribbon cables (5) and tested each ribbon cable wire for continuity.

Well 2 ribbon cables had no broken wires in the ribbon, but the other 3 ribbon cables had broken wires and the one being used for the airspeed board had many broken wires, 18 wires out of 20. That suggested to me Rainier used 20 pin cables in his designed so there was redundancy by running the same signal through a few different ribbon wires.

I hope by replacing these FFC ribbon cables, it will be a huge step forward in resolving those niggling little issues that have just started.

I did have someone say, why bother going through all this, just replace the panel and EFIS. Well I have a bit of a theory as to why all these issues have been coming at once, it's because the aircraft lived most of its life on a sealed runway. When I purchased the plane it started operating off a grass airstrip.

So the instrument panel is now getting small jolts on take offs and landings and those wires that are fatigued, are now breaking as they get these these small jolts. I am hoping there will be a light at the end of the tunnel once all these fatigued wires have broken and I have been able to replaced them.

So I must be getting close, once all these FFC ribbon cables are replaced.

One last thing, if you are thinking about replacing your FFC ribbon cables, take the time to find a youtube video, on how to release the ribbon from the socket, don't just try pulling the ribbon cable from the socket.

Undoing the socket clip is very easy once you have seen how the clip works.



Cheers
JimJab

[JimJab]

Hi All,

Here is an up date, the ribbon cables arrived from Element 14, a bit slow as they had been on backorder from overseas.

I replaced all the FFC ribbon cables in both my Voyagers. I was anticipating by replacing these ribbon cables in the pilot EFIS, this would solve many of the issues of this EFIS not reading correctly.

Well, after some benching testing, I am jumping for joy, it's looking very promising.

Now on bench testing, the volts are now reading normal, the line on the AOA gauge now moves with airspeed and it has never moved no matter how I calibrated the AOA. The airspeed now reads zero as it should and when bench testing it with a length of hoses and using a "cold" hot air gun blowing flat out, the airspeed does reads about 37 knots on both my Voyagers.

Warning, Don't use any type of compressed air near any pitot tube or airspeed indicator, the gauge will most likely never work again.

Here is a pic

Voyager Ribbon Cable Replacement

Efis Replace Ribbon CablesR3.jpg (199.29 KiB) Viewed 5516 times

[JimJab]

Well, If you have been following this thread and thinking about replacing your flat ribbon cables in your Voyager EFIS here is some important information.

Warning

When you open up any electronic equipment, you should always take notice and even take photographs of where and how any linking or ribbons cables are routed around the place.

There are very good reasons why manufacturers have routed cables in such a way and we should route them in the same manner when replacing them.

I found my ribbon cables routed all over the place and in no particular way with different brands of ribbon cables. So I guess someone has been in there and replaced some of the cables before.

See the parts that are circled in pic, this is the EFIS's high voltage power supply for the screen. Don't let your ribbon cables touch these components. As it's possible the high voltage can arc to and through your flat ribbon cable and burn small holes in and through it.

This may only damage your ribbon cable, but just as easily damage your EFIS beyond the cable and cost much to fix it.

So make sure you route all your ribbon cables away from this high voltage power supply area so the ribbon cables can't touch these components.

Cheers
JimJab

ScreenHighVoltagePowerSupplyV1.jpg (90.71 KiB) Viewed 5388 times

[JimJab]

Hi All,

I am thinking this will be my last update for this thread.

But one last thought, I've had my EFIS's in and out of the plane many times to open them up. Of cause this movement of wires both behind the instrument panel and inside your EFIS where they may have been fatigued by vibration, can also help weaken or even help break those wires during this process, so try to be gentle with your wiring if it's older stuff.

Moving on, it's now several months since having the flat ribbon issues with the Airspeed, AOA, Altitude and Voltage readings fluctuating and so I replaced all the EFIS flat ribbon cables in my Voyager EFIS's.

Well, I am happy to say, my EFIS's Engine Management and Flight Gauges are showing to be rock solid with their readings and values over the last several months.

Now lets hope I can get to the bottom of the GPS issue ????.

Do I see light at the end of this tunnel, Yippee

Cheers
JimJab.

[JimJab]

Hi All,

Just a quick up date, it's been a year since replacing the flat ribbon cables in my Voyager EFIS's.

I am happy to say that all the flight instruments that started to be flakey and read erroneously, have been reading rock solid since the ribbon cable replacement 12 months ago.

I think we have arrived at the end of the tunnel for this issue.

Cheers
JimJab.