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After learning a plug-compatible graphic display monitor for my GRT EIS 6000 was not going to happen anytime soon, I decided to upgrade to the MGL XTreme EMS - the "twin" to my XTreme EFIS:
On the GRT EIS, all the sensors terminate in two 25-pin D-sub connectors that plug into the EIS 6000. MGL approaches it differently with a "RDAC" interface box that the sensor wires individually connect to and then the RDAC communicates the data via a CAN bus to the EMS. This has the advantage that the RDAC can be located firewall-forward and only the small CAN bus cable needs to penetrate the firewall. However, since all my sensor wires already were inside the cabin and behind the panel with the D-sub connectors, I've elected to mount the RDAC on the inside of the firewall.
It seemed to me that it would be much easier to connect the RDAC to the sensors by making it "Plug and Play," rather than having to tediously cut each wire out of the harness and individually connect it to the RDAC while sitting in the airplane! So, I made up two harnesses terminating in the appropriate D-sub connectors and using the appropriate J and K junction wire for the EGT/CHT harness. This was much easier since I could sit in the comfort of home, have a cup of coffee, and wire up the harness at my leisure! It came out looking like this:
I've made up a third sub-panel for my instrument panel. I plan to cut-out the left side of the panel where the EIS box, ELT panel, trim indicator, and EIS alarm light were installed. The XTreme EMS and everything else will then go into the sub-panel. I'm trying one of the "Click Bond" nutplates to secure the left side of the panel.
Tomorrow, I'll cut out the panel and hopefully get the RDAC and maybe even the EMS installed!
(not affiliated with MGL)
A curious malady strikes about 100 hrs after the first flight! You begin to tinker, refine, and modify almost everything you can get your hands on! So far, I've installed an autopilot, ADS-B, 4-point seat belts, lithium battery, and the list just goes on and on!
Seriously, though, it just began to bug me that the alpha-numeric data from the GRT EIS looked awfully dated alongside the MGL EFIS. Now, I'll have a matching, "twin" display and the data will be comprehensible at a glance. One great thing, though, the MGL EMS still has an output for an "idiot light" alarm, just like the GRT EIS had. That really makes for safety when "low and slow" as you can just give an occasional glance at the panel ... if that light is out, everything is A-OK!
It certainly is fun that we can do about whatever we can think up (within the laws of physics and aerodynamics!) with an E-AB!
I love my MGL Mini EFIS. When my oil pressure sender was going out I would get a great big red warning alarm across the face of the it saying something is wrong do something. If I had just normal gauges I would probably missed it or seen it much later, hopefully not when the engine was stopping. That big red alarm right across the face of the EFIS is just fantastic, worth it's weight in gold
Wow, those click bond nutplates are what I was looking for when I put my panel together, no flipping nuts on the back trying to get to. I just put a stick grip with trim and flaps on my plane and was under the dash soldering wires because it was to hard to get at the nuts of the trim switch to pull it out and do it in front of the panel. If I had only known these were available!!!
Waal, this here's all "Greek" to me, and probably too expensive too. I just have to economize and stick to my steam gauges, I reckon . . . Still, I'd like to have some idiot lights (obviously) to back up the ancient panel I have, and some way to hook up my cheap android-type tablet (Samsung Galaxy 3) for navigation and whatever else it might be capable of. But I'm gonna take my time, and first things first. A lot to do, so I know what you mean about the tinker-bug. Too bad I ain't qualiefied.
Today, I finished the subpanel and EMS installation. I used the subpanel as a template to mark in red the areas that needed to be cut out of the panel: (By the way, the orange object protruding from the panel is the Click Bond fixture that hold the nut plate aligned and against the panel while the acrylic adhesive sets.)
I then used a Dremel cutting disc to cut away the panel and a file and Scotchbrite to dress the edges. I put a towel under where I was working to try to keep chips out of the electrical system and had my son follow the cutting disc with a vaccum cleaner:
After plugging in the RDAC and CAN bus and securing the wiring, I fired up the EMS and did some sensor configuration. The Jab 3300 has VDO senders - the oil temp sender is 150C and the oil pressure sender is 5 bar. I did an engine run and was pleased to see a nice, stable RPM indication (the tach pickup is off one of the AC current wires from the alternator and the configuration is 6 pulses per revolution for the Jab 3300) and all the pressures and temps looked normal, except for the OAT. I had not changed-out the OAT probe (MGL includes a new one with the EMS) to see if I might get lucky and it be compatible, but it wasn't. So, all I have left to do now is change out the OAT probe and calibrate the fuel senders and I'm done!
I've had three gremlins to chase down in flight testing of the new EMS, and I think I've resolved two of the three:
1. Although the tach was remarkablly stable on the ground, I found that at about 1700-1900 rpm, the tach reading would double, but the tach was normal above or below this range. This is also about the rpm range where the alternator kicks-in charging current on a Jabiru, so I suspect some sort of secondary signal is being counted. I flipped the ballast resistor dip switch "on" on the RDAC and this cured the tach doubling, but it knocked out reading rpms below about 900 rpm! So, I adjusted the variable pot on the RDAC that controls rpm sensitivity and got the low rpm reading back. Seems fixed but I need to flight test to be sure nothing has affected rpm reading on the other, high end of the tach.
2. The OAT was also stable on the ground, but fluctuated several degrees in-flight. The OAT input goes directly to the EMS box and not the RDAC. I had grounded the EMS to the RDAC since there were convenient grounding terminals there. Apparently that was a mistake. I moved the ground to the airframe and the OAT immediately became stable. Today, I plan to permanently attach the EMS ground to the avionics ground bus where I should have put it in the first place!
3. The oil pressure reading is fluctuating wildly and the sender was working perfectly before the upgrade. Although the vast majority of problems with senders is usually proper grounding, I'm wondering if perhaps I stripped the oil pressure sender wire (which carries +5v to the sender) too short and have a bit of insulation trapped in the RDAC terminal along with the bare wire. I'm going to re-check the connection today and then flight test. If the problem persists, guess it's time to pop the cowl and double-check all the grounds from the sender to the RDAC.
None of this, however, seems to be related to the "plug and play" harnesses I fabricated! Guess a little troubleshooting is to be expected!
Just a follow-up ... all issues are resolved! I moved the tach pickups over to the mags and have completely stable readings through the entire range. Properly grounding the EMS resolved the OAT stability. A new, genuine VDO 5 bar oil pressure sender is giving rock-steady pressure indications on the EMS. Weird that the sender would fail at the changeover, but I guess stranger things have happened!
As usual, nicely done! Appreciate the effort you put in documenting and posting to the forum.