CALIBRATION

[Clay]

I might be wrong on this, but I don't think you should ever run any of the "ground" pins on analog 1 or 2 to the airframe ground. These are grounds for various sensors. For example, I have my fuel flow sensor connected to pins 7, 19, and 6 on Analog 2. 7 is signal, 19 is ground, and 6 is +5v.

Also, don't ground any sensors to the airframe (get ungrounded sensors). I had some of the early grounded EGT sensors that didn't work, and when I switched to the ungrounded type, they work fine.

-Clay

[jschroeder]

I heartily concur with Clay: Don't connect any sensor or pins on the CPU to ship's ground. We ran into this trying to calibrate the current sensors and finally got a hold of Greg. He said there is a ship's ground and an instrument ground and don't mix them. Bob Northrup said that a ground is a ground is a ground ... and according to Greg, that is not true.

Cheers,

John

[bob_northrup]

Well, Clay is partially correct and sorry John, but wrong! We have been tying a ground from one of the analog connectors to airframe ground since day one. If you were to look at any of the sensor maps we prepare for a customer, you'll find that is always included. Where Clay is correct is that there are some sensors we do want grounded directly to the EFIS and he is also correct in that ungrounded EGT's are the only ones we endorse and supply.
There have been applications where we've recommended a separate instrument ground, particularly in some composite aircraft that if not wired correctly can have some pretty noisy grounds.

[bob_northrup]

Originally Posted by randy_c

I am using Westach sensors for my engine monitoring on EFIS One. After a steep learning curve and a few calls, I finally understand how to set up a calibration array, and I placed resistors in series with each sensor to move the resistance range up above 500 Ohms to mach the high range jumper positions. Talikng about Westach 399S1 and 399S7 temperature sensors here, they are supposed to have identical resistance ranges, one just has a shorter end on it.

I got two of them to calibrate nicely after boiling water and then oil and playing with ice cubes etc, I got a calibration array that has them reading from ambient on up past the redline area. These are on analog 1 resistive input pins and each has it's own grounding to pins 14 and 27 on analog 1.

The other two sensors have always showed an AD value of about 680 to 700. Nothing makes them change, (applied heat and cold to the sensors, no response). Next I hooked up an ohmeter to the signal and ground leads and heated and cooled the sensors and they do respond properly, although I did not actually measure the resistance, just verified that they respond over a range when heated and cooled.

Next I verified I could reproduce these results directly at the analog 1 DB37 cable plug. I still get continuity and resistance change with heat and cold. I have the interface boards installed so my sensor leads terminate at set screw terminals, then continue to the EFIS box via DB37 plugs and cableing that I made up, so I tested in stages.

I even verified continuity through the EFIS one analog plug, through the ribbon cable inside the box and out the next plug as I know these ribbon cable connections can be troublesome. Still OK.

I began to suspect a grounding problem. Analog 2 has a ground wire going from pin 19, directly out to my common airframe gound. I checked resistance from pin 19 on analog 2 to the EFIS box and it quickly pegs the ohmeter to 0 indicating a solid ground. The two sensors that are giving me grief share a ground on pin 30 on analog 1. When I checked pin 30 resistance to the box, I got about half range deflection of the ohmeter... Pins 14 and 27, analog 1, grounds for the two working sensors show about a 7/8 deflection of the ohmeter needle, but not a solid ground like pin 19 on analog 2.

Should all of these gounding pins show a solid ground connection to the EFIS box when checked from the pin on the box to the metal box itself?

Thinking I may have found the problem, I removed the sensor ground leads from the interface module and connected them directly to the airframe ground with a jumper, just to test. Still no response, those AD values still stay between 680 and 700 and do not change with heat or cold applied to the sensors. So much for the grounding theory for explaining why the sensors do not work. Still I have the feeling that a pin labled ground on analog 1 or analog 2, should peg the ohmeter when checked for it's connection to the box, like pin 19 on analog 2 does.

Any ideas or comments that might help?

Randy, give me a call this afternoon (and no, I don't work at 5:30 on Saturday evenings) and I can show you some tricks to test your analog channels.

[rjc3677]

To: Mr. Greg Richter

The Efis is reinstalled ... Connected power plug to Efis box & screen first, checked OK, Then added one plug at a time checked OK.
(1) (The attitude keeps rolling and pitching up/down) FIXED NOW
(2) (The HSI keeps rolling and will not lock on the heading) FIXED NOW
(3) (The manifold pressure is jumping up/down) FIXED NOW

(1) We still have an altitude problem ... It is better but still not right ... NOT FIXED

(2) The flag on the BACKCOURSE is still not working, the deviation needle is always on and to the far left (with the radio on or off) needle will swing right, left and center with good signal from test box ... NOT FIXED

(3) Now we have a New Problem ... When I pull the plane out to test fly, it took about 30 min for the GPS to come up, (I didn't think much about it because the GPS needed to find itself for the first time). After that flight I turned the Efis back on and the GPS came right up.
We went to lunch then returned to airport to do more test flying. This time it took 30 min to 35 min to get GPS again, so I thought I'll turn it off, then right back on to see If it will grab GPS ... NO GO.
This time it never got GPS again ... This time we spent 30 min on the taxiway then flew the plane for 1 Hr and the GPS never came on again.

Now we don't have GPS ... Before you ask:
(1) Yes, I checked the connection.
(2) Yes, The ant is sitting on the dash looking out the windshield.
(3) Yes, There is good Satellite Signal.
(4) Yes, The Garmin 530 comes right on with good Satellite Signals.
(5) Yes, I retryed it again today (3/16/06) let the plane sit out for 1hr & 35mim with the Efis on ... NO GPS connection.

And most important (Greg) there has been NO WIRES CHANGED ON THE AIRFRAME.

where to from here?

Thank You
Richard Cano
PH# 409-763-5940

[Greg]

Time to first fix is determined by:

1. GPS knowing where it is, what time it is, and having full Almanac data
2. Good view of the sky
3. Good antenna and feedline performance

If you are seeing 8-11 satellites, #2 and #3 are good. So then it's either:

1. Dead GPS battery
2. Incomplete almanac

The battery is rated for 10 years, so I suspect it's probably still fine. We've not had one fail yet, but this would be the place for it.

The almanac on the Jupiter 12 radio can take a while to download. If the machine is weeks out of date, you can wait as long as 45 minutes for it to load everything. Until then, it'll cold start and do a sky search, which takes a while and can take up to 30 minutes. That's why you powered down, back up and it took a while again. Never got the word.

If you got zip in an hour, I suspect you may want to measure the voltage coming out of the BNC connector and make sure it's about 5v. I've also seen BNC connectors get their center pin pushed up and the connection go intermittent. Try and push the center pin on the cable and see if it's in solid and poking out the proper amount.

Since you flew for an hour and didn't get anything, and sat on the ramp for an hour plus and no go there, I suspect the antenna connection or shading of the antenna. You never mentioned how many sats you saw when it was up, but if it was 8 or 10, it's the connector.

[edwardoc]

Am going to schedule a certification for my altimeter and transponder one of these days. What is involved in certifing them? I am assuming most places will not know how to correct altimeter array unless I'm there and same for the SL 70. ( by the way how is SL 70 readout corrected if it is found to be in error.) I have checked with ATC and every time I ask them what they are showing it is always what I'm indicating on the EFIS 1 altimeter. So there seems to be no error.
Has anyone printed a procedure for calibrating the EFIS altimeter and transponder in a shop. I have never owned an airplane before and never taken one to a shop. Are they going to roll their eyes when they see the EFIS 1 rather then the standard guages.
Anyone have any suggestions comments on what to expect. Plan on doing this in Panama City FL or Greeley Co depending on when I move.

I am just getting started in calibration.

I read the write-up by daforster on his thermocouple calibration, and I like the technique of hot cooking oil. I think my question is more basic.

On Analog 1, the type K thermocouple channel comes up with a 10v range. Since thermocouples only put out millivolts, is this correct? When connected to a thermocouple, the AD values are quite variable. I want to calibrate a couple of thermocouples for oil and water temperature for diagnostic purposes, and need to have a range from 80F to 250F, which is lower than normal CHT and EGT type readings.

Bill Schertz

[bob_northrup]

Some of our customers have had to use the EI P-120 temperature probe, which is a K type thermocouple, just because they ran out of available channels. It works very well in the range you are interested in using the BMA EGT F preloaded curve and the 10 volt input range.

Originally Posted by bob_northrup

Some of our customers have had to use the EI P-120 temperature probe, which is a K type thermocouple, just because they ran out of available channels. It works very well in the range you are interested in using the BMA EGT F preloaded curve and the 10 volt input range.

Bob,
I am new to this, but I think something isn't doing what it should. I will do more tests tomorrow, but the AD values vary widely, and when I load the Type K table into the channel 26, it registers ~600 degrees while at room temperature.

If I heat the probe in hot water on a hot plate, and then set the AD value/temperture in the same vicinity as the thermometer, the displayed value will then drift up or down with time. One time the AD values suddenly went from ~1300 to 0 . I shut the system down for a while, rebooted it, and it was back to ~1300.

Bill Schertz