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UBG16 service?


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I’m having multiple issues with my UBG.  Several probes not reading at all or incorrectly.  Fuel flow is all over the place.  With as many issues, I’m guessing it’s more related to the unit than the probes.  Any recommendation in southwest AZ for a shop that knows what they’re looking at instead of parts swappers?

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Expect a grounding issue...

Any maintenance done lately? Ground straps all clean and connected?

Lots of ground challenges between instruments, engine, mount, FW, and instrument panel...

Since many are effected, it is a hint that some power supply or ground may be at fault...

Paul has shared a great idea...Since we have an EI guy around here check In with @oregon87.

He typically gives a contact that makes the most sense for the challenge...

PP thoughts only, not a mechanic...

Best regards,

-a-

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1 hour ago, gsxrpilot said:

I've heard the tech support at EI is really good. They might be worth a call if you haven't already.

I haven't yet, but I was planning to tomorrow.  I'm sure they will suggest some shops, but I prefer personal recommendations. :)

It's a functional monitor, and I'm not ready to ditch it until I'm after I get an autopilot.  After that, it's new panel time with an EDM.

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A bad ground would be reflected in the UBG-16 not working at all, not random intermittent indications.  When you say that several probes are not reading correctly or not at all, how exactly are they behaving?  What temperatures for each function are you seeing?  Additional information will aid in troubleshooting.

In regard to fuel flow, the flow transducer does not wire directly to the UBG-16, rather it connects through a module called the FM-FLOW.  "All over the place" meaning?  Is it jumpy high?  Low?  Sometimes read 0?  Jumpy is almost always connection related and I would certainly start there.  Depending on the age of the installation, the connectors likely used were the male/female spade connectors.  The crimps are susceptible to failing over time and the female connector can loosen, as well.  Additionally, corrosion on those connectors can certainly cause intermittent.   

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I have a UBG16, and the oil pressure is erratic, but I noticed it works fine when I reach under the panel and push the connector together.  So, it's not enough problem for me to fix since I plan to go with a primary before too long.  I had mine sent in to EI when my display started to miss number segments and the screen began to delaminate.  They have a bench fee, but it was reasonable.  They returned a display that looked new.  

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On 6/24/2019 at 12:55 PM, oregon87 said:

A bad ground would be reflected in the UBG-16 not working at all, not random intermittent indications.  When you say that several probes are not reading correctly or not at all, how exactly are they behaving?  What temperatures for each function are you seeing?  Additional information will aid in troubleshooting.

In regard to fuel flow, the flow transducer does not wire directly to the UBG-16, rather it connects through a module called the FM-FLOW.  "All over the place" meaning?  Is it jumpy high?  Low?  Sometimes read 0?  Jumpy is almost always connection related and I would certainly start there.  Depending on the age of the installation, the connectors likely used were the male/female spade connectors.  The crimps are susceptible to failing over time and the female connector can loosen, as well.  Additionally, corrosion on those connectors can certainly cause intermittent.   

@carusoam thanks for the heads up.

@oregon87 here's some additional info.

 

I have 2 CHTs that intermittently read around 75-80f. Even in flight. My OAT is always 10-15 degrees different from both the Scott thermometer and the ATIS temp.  My oil temp gauge is always around 75-80f.

 

FF will read anywhere from 0.0 to 18GPH regardless of flight phase or leaning.  As far as I can tell, there aren't any connections other than at the boxes behind the panel, the wires go in there and I'm not sure how they are connected.

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CHT and oil temp trouble shooting:  Assuming 75-85°F is ambient temp in the cockpit, or what would be expected behind the panel?  If so, it is likely you have a damaged open probe, bad connection at the probe, or a broken harness.  Anytime there is an open, due to the lack of both  "cold" and "hot" thermocouple reference joints, the temperature displayed will be that of the temperature compensation diode at the rear of instrument.  

OAT: Where is the probe located?  Very often, this will affect how the temperature indicates when compared with ambient.  A couple of easy tests to verify the accuracy.  Remove the probe and submerge it in an ice bath (70% ice/30% water).  It should read 32°F, +/- a couple of degrees.  A similar test can be performed with boiling water and you should find a temperature indication of roughly 212°F.  Comparing temps with known values is really the best way to verify.  If the test results in accurate temps, the probe should be relocated.  

Fuel Flow: Is the reading jumpy from 0-18GPH?  Does it slowly climb and fall between those values?  There is most definitely a FM-FLOW installed between the UBG-16 and the flow transducer as it is needed to convert the UBG-16's temperature channels to read a function other than a temp.  However, I do not feel that is where the problem lies as it appears to be providing voltage to the transducer and it would be exceedingly rare for a module to intermittently provide voltage then not.  I would recommend replacing the three connectors at the flow transducer and clean the transducer with non-abrasive mineral spirits, gently tapping it over a white surface and observe if any debris is dislodged.  If after performing those steps, replacing the flow transducer should be considered.  

Edited by oregon87
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@oregon87

Ok. I'm getting somewhere.  I found at the fuel transducer, there were indeed Spade connectors. However, that wasnt the issue. The issue was a bad crimp. The wire wasn't actually crimped into the connector anymore, just held there by the pressure of the zip ties. Redid those connections with olc-1 connectors.  CHT I found some rubbed through insulation.  

Fuel flow and all cht/egt now functioning.

OAT and oil temp is a different story.  It's either in the harness or the unit.  There's a few cannon plugs off the UBG.  I traced the oil temp all the way to the plug.  The wires there were already spliced with OLC-1 connectors.  I undid the splice and directly hooked a brand new probe there.  Still no joy on the UBG.  same with the OAT.  it seems the problem is either in the cannon plug, the factory (? I think?) Wiring from the cannon plug to the UBG or the UBG.  

Thanks for the trubleshooting.  Any ideas on where to go with the OAT and oil temp?

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8 minutes ago, ragedracer1977 said:

@EricJ @N201MKTurbo is this something that would be up Bashir's alley?  My IA is a nuts and bolts guy.  He'll watch me work on electronics, but he doesn't really do it.  I'm getting to the point on this where we might make things worse rather than better, lol

I've no idea, you could ask him.   It's certainly within his expertise but I don't know whether he'd be interested in it or not.  He did your static cert, no?   If he didn't want to do it he'd probably have somebody to recommend.

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16 hours ago, ragedracer1977 said:

@oregon87

Ok. I'm getting somewhere.  I found at the fuel transducer, there were indeed Spade connectors. However, that wasnt the issue. The issue was a bad crimp. The wire wasn't actually crimped into the connector anymore, just held there by the pressure of the zip ties. Redid those connections with olc-1 connectors.  CHT I found some rubbed through insulation.  

Fuel flow and all cht/egt now functioning.

OAT and oil temp is a different story.  It's either in the harness or the unit.  There's a few cannon plugs off the UBG.  I traced the oil temp all the way to the plug.  The wires there were already spliced with OLC-1 connectors.  I undid the splice and directly hooked a brand new probe there.  Still no joy on the UBG.  same with the OAT.  it seems the problem is either in the cannon plug, the factory (? I think?) Wiring from the cannon plug to the UBG or the UBG.  

Thanks for the trubleshooting.  Any ideas on where to go with the OAT and oil temp?

Here's a few steps to troubleshoot a temperature.  These apply to both CHT and oil temp.  Disconnect the probe and connect a multimeter to the two leads running back to the UBG-16.  Make sure the multimeter is set to ohms.  You're going to use the small voltage provided by the multimeter to drive the temperature channel which effectively simulates the signal from the probe.  When the multimeter is connected and the UBG-16 is powered up, that channel should be pegged full positive or full negative, depending on the polarity of the multimeter leads.  Do not depend on the bar graph solely, make sure to toggle to the cylinder being tested and observe the numerical value at the bottom of the display.  Swapping them will drive the indication the other direction.  If you do not see the expected result, perform the same step, but at the UBG's EGT or CHT connector, thereby removing the harness from the equation.  When looking at the front of the instrument, the CHT harness is on the right, EGT on the left.  If the channel spikes when driving from the rear of the gauge, you've likely got a broken harness.  If no action when driving from the rear of the gauge, the problem is internal to the display.  

 

Edited by oregon87
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@oregon87 I’m finally getting somewhere.  It looks like the wiring is incorrect from the get go.  It was never right...  

It would seem the original installer installed the EGT to the CHT harness and vice versa. Rather than fix this, they just swapped the plugs.  Or maybe they didn’t know.  I was able to swap the plugs and get everything reading correctly, except the EGT and CHT were reversed on the display, and of course that won’t work.  So, I swapped them back and reprogrammed the UBG to match the wiring.  Now almost everything seems to be functioning correctly, except “bar 7”, which should be oil temperature, but is not because they wired something else into position 5.

the harness is such a cluster, we’re essentially going to have to rebuild the whole thing to sort out what’s what.

It really shouldn’t be too difficult a project, just need to cut a bunch of zip ties and go to work. At least for now, I have the items functioning, except Amps, which I believe is what they put to channel 5.   But I’m really not sure,  it could also be carb temp.  Like I said, it’s a mess.  It was not done cleanly at all.  See pic, LOL. 

 

 

7880F5BD-487A-4BB0-A901-4E1F9FD416C1.jpeg

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Brice,

Now is a good time to inventory what type of sensors are doing what job...

CHT and EGT are most often thermo-couples... check them all to be continuous, color coded the same way, nothing odd added to extend them....

OilT is most often a thermistor... a temp sensitive resistor...

Every now and then a ship’s CHT sensor is a thermistor as well...

FF is a magnet that moves past a sensor to give pulses of some voltage...

Amps is a voltage drop reading taken across the ship’s calibrated resistor called a shunt... the Amps are actually volts being displayed as amps...

 

Thanks to @oregon87 for supplying the EI support.

Best regards,

-a-

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@oregon87 I’d like to just rewire everything.  Is it possible to buy from you new pins (male and female) for ALL the cannon plugs and the tools to remove the old pins? This install was done so poorly, I can’t see anything else to do but re-do it.

i have the UBG, MUX8A, FM-OP, FM-VA, and FM-FLOW modules.

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9 minutes ago, ragedracer1977 said:

@oregon87 I’d like to just rewire everything.  Is it possible to buy from you new pins (male and female) for ALL the cannon plugs and the tools to remove the old pins? This install was done so poorly, I can’t see anything else to do but re-do it.

i have the UBG, MUX8A, FM-OP, FM-VA, and FM-FLOW modules.

I suggest you buy a new EI harness. A quality Certified crimp tool cost many hundreds of dollars. Very few A&P's even have this equipment which is basic standard stuff for a avionics tech.  

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5 minutes ago, kortopates said:

I suggest you buy a new EI harness. A quality Certified crimp tool cost many hundreds of dollars. Very few A&P's even have this equipment which is basic standard stuff for a avionics tech.  

As far as I can tell, the factory harness portion is fine (it’s still on the UBG-not in the pic).  This all the stuff you have to build.  I have a pin crimp tool.  No, it wasn’t cheap.  No, my IA didn’t want to invest in it, he figured pliers would be OK (remember when I said he was a nuts and bolts guy? :rolleyes:). I didn’t agree so I bought the tool and let him borrow it.

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As far as I can tell, the factory harness portion is fine (it’s still on the UBG-not in the pic).  This all the stuff you have to build.  I have a pin crimp tool.  No, it wasn’t cheap.  No, my IA didn’t want to invest in it, he figured pliers would be OK (remember when I said he was a nuts and bolts guy? :rolleyes:). I didn’t agree so I bought the tool and let him borrow it.

I wondered if the sensors you listed were on the EI harness or not. That explains it. Since you're tooled up, you can get a good supply of the connectors from Mouser Electronics or Digikey (that's where I go once I have part #s) or from EI as well.


Sent from my iPhone using Tapatalk
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@oregon87 Well, another update.  The image below is how the plugs at the UBG are wired.  They're wrong.  I don't think the installer understood the directions.  I'm not sure what he did... 

Oil temp should be on channel 5 on the left harness (its on channel 5 of the right harness). Where the oil temp should be (channel 5, left harness), the green RS232 input wire for the MUX8A is connected to half the channel. Channel 6, the blue RS232 input wire for the MUX8A is connected to half the channel.  Then, the RS232 for Cascade operation is connected to the RS232 output of the UBG16.  

We got the harness all cleaned up, eliminated about 15 FEET of unnecessary wire.  

So, I'd still like to buy some pins (male and female) and the removal tool.  

Also, can you confirm my thoughts?

I need to remove the RS232 MUX8A inputs from the left connector of the UBG, and then connect just one (it doesn't matter which, right, as long as the corresponding dip switch is selected?) to pin 9 of the center connector on the UBG?  Then I can swap the oil temperature probe pins to channel 5 of the left connector.

I'm pretty sure that's where I'm at.  We programmed the UBG to match the way the wiring currently is, but I'd really like bar 7 to display the oil temp, so I need to make that correction.  And, it would be nice if the MUX8A actually worked instead of just taking up space!

 

20190630_223936.jpg

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1 hour ago, MB65E said:

Well done!! You know know the wiring better than anyone else! I really can’t stand some of those spade connections. I try to replace them whenever I can. 

-Matt

It's pretty frustrating that a 'pro' installed this.  In the 15 or so years (I'd have to check the logs to see exactly when) it's not possible that it ever worked right.  And how did the guy that paid for it let that go??

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Not ignoring this thread.  Just got back into the office this morning and will digest all of this and make my best recommendation.  We'll be launching a new rebate in the next couple of days in preparation for Oshkosh.  ragedracer1977, as you were considering upgrading from the UBG-16, I'm going to send you a PM discussing a few different options.  

Edited by oregon87
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10 hours ago, oregon87 said:

Not ignoring this thread.  Just got back into the office this morning and will digest all of this and make my best recommendation.  We'll be launching a new rebate in the next couple of days in preparation for Oshkosh.  ragedracer1977, as you were considering upgrading from the UBG-16, I'm going to send you a PM discussing a few different options.  

Thanks for the help!  I'm just really glad to finally have a functioning monitor.  All this time I thought it was faulty probes or a failing unit, but it was just a junk install.  I checked the logs, it was installed nearly 20 years ago.  In all that time, it's never been right.  Unbelievable.  

Dave is sending me the final few pieces I need to get it 100% and I can tell you I'll be looking pretty hard at their primary replacement instrument when the time comes!

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