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Brittain Turn Coordinator Elec Off Flag


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The Elec Off flag showed up on the Brittain.  The circuit breaker is on and wiring all appears good.  Haven’t found the connector where I can check input voltage.  Could it be something wrong internally, or does it have to be a power supply problem?

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1 hour ago, N201MKTurbo said:

The parts in the power supply vibrated apart. If you have soldering skills, take it apart and resolder the parts and it will work again.

Are you referring to power supply inside the TC? How complicated is PS; any electrolytic caps that might need replacing?

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Thanks for the replies and information!

I have great soldering skills.  What I don’t have is good ability to work in tight places while standing on my head.

So since it is dual vacuum/electric, I am also dealing with low vacuum, a little over 4”, maybe closer to 4 1/2.  I am going to try and find the relief tube and clean it.  Could low vacuum be related to this problem?

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The Brittain TC electrical power supply has an inverter, a little 3-1/2" dia. and 2-1/2" tall  black cylindrical object attached to the TC that does something electrical.  Not sure what it does.  Find that, and you'll find where the DC power cables lie.   Anybody know what it does?

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The one in my old M20F had an external power supply on the end of a cable attached to the TC. It was mounted to the side wall just above your left knee.

I think there were different designs of powersupplys. The one in my F had two phenolic boards that were held together with aluminum rivets. The components were soldered into brass eyelets crimped into the boards. The components are all mil spec and I wouldn’t suspect any component failure. The parts just vibrate apart and the solder joints fail. 

I don’t think most instrument shops can repair the power supply. 

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  • 1 year later...

Bringing back the old thread.  

I got an extra inop Brittian TC on my desk and decided to troubleshoot to see what I can figure out why it isn't working.   so far, this is what I have learned.  

  • There are 4 wires that feed from the inverter to the gyro motor.  I'm yet to understand why 4 wires were involved since most brushless AC motor runs on 3 wires
  • All 4 wires are connected to the same coil.  Continuity test using a multi-meter confirms this.  Therefore, I do know this is not a 2 poles stepper motor
  • The TC can run on either electric, vacuum, or both.  The design appear to have some redundancy builtin.  
  • The Elec off flag is also powered by the inverter with 5v AC at the same frequency as the 4 wires to the rotor (about 290 Hz). The power to the flag is supplied using separate pair of wires (blue and brown).  

In the TC I'm working on, failure mode is rather interesting.  Initially, I thought the rotor bearings were shot, which cause the rotor to become stuck.  After carefully examination, the bearings are working just fine.  Instead, the motor coil seems to have become permanently magnetized.  This causes the rotor to become stuck in one position.  Even if inverter power is remove and vacuum is supplied, the rotor could not rotate past the stuck position.  of course, there is one other possibility - the permanent magnets are the rotating assembly may have become dislodge and shifted....

Any though or info would be appreciated.  

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On 12/2/2020 at 7:15 PM, corn_flake said:

There are 4 wires that feed from the inverter to the gyro motor.  I'm yet to understand why 4 wires were involved since most brushless AC motor runs on 3 wires

It's a 3 phase signal, not just ac.  https://en.wikipedia.org/wiki/Three-phase_electric_power  This eliminates the need for a set of brushes on the motor inside the turn coordinator.  I'm guessing that the 4th wire is ground. 

 

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  • 2 months later...
On 12/3/2020 at 2:15 AM, corn_flake said:

Bringing back the old thread.  

I got an extra inop Brittian TC on my desk and decided to troubleshoot to see what I can figure out why it isn't working.   so far, this is what I have learned.  

  • There are 4 wires that feed from the inverter to the gyro motor.  I'm yet to understand why 4 wires were involved since most brushless AC motor runs on 3 wires
  • All 4 wires are connected to the same coil.  Continuity test using a multi-meter confirms this.  Therefore, I do know this is not a 2 poles stepper motor
  • The TC can run on either electric, vacuum, or both.  The design appear to have some redundancy builtin.  
  • The Elec off flag is also powered by the inverter with 5v AC at the same frequency as the 4 wires to the rotor (about 290 Hz). The power to the flag is supplied using separate pair of wires (blue and brown).  

In the TC I'm working on, failure mode is rather interesting.  Initially, I thought the rotor bearings were shot, which cause the rotor to become stuck.  After carefully examination, the bearings are working just fine.  Instead, the motor coil seems to have become permanently magnetized.  This causes the rotor to become stuck in one position.  Even if inverter power is remove and vacuum is supplied, the rotor could not rotate past the stuck position.  of course, there is one other possibility - the permanent magnets are the rotating assembly may have become dislodge and shifted....

Any though or info would be appreciated.  

Hi corn_flake,

I'd like to resurrect this thread, since I've run into the same problem after debugging numerous annoying little problems with my 1968 M20G, one of them being the continuous display of the "Elec off" flag on my Brittain turn coordinator, which still works fine, to my great surprise (found out it's vacuum-operated as well).

As cctsurf wrote, it's a 3-phase signal with one of the 4 wires being ground.

I had a closer look inside it and one of the components looks like it's a fuse. I'm going to test whether it's blown - I assume it is, since the 3-phase wires to the turn coordinator were twisted together and fixed with *very* old insulating tape, some of which had come off, probably causing a short-circuit somewhere.

Have you managed to fix your problem since your post?

Best regards from Germany,

Gerald

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  • 3 weeks later...
On 3/2/2021 at 1:20 PM, nosky2high said:

What repair center(s) still do overhauls on Brittain PC wingleveler (Vac/electrical) turn coordinators?

According to Kevin Westbrook, former Brittain technican, the Brittain EVT TC's can be overhauled through Porter Strait in Tulsa, 918-838-8711.  Kevin can be reached at 918-521-5139.  

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