instrument cluster keeps tripping circuit breaker

[rbridges]

just started yesterday.  not a problem prior to that.  it's a 5 amp circuit breaker that connects to the instrument cluster strip.  mine has the J model strip, not that it necessarily matters.  I left a message for my avionics guy to call me.  In the meantime I was trying to find some answers.  I figure it's either a short or a failing circuit breaker.  I looked under the glare shield, and nothing jumped out at me.  The circuit breaker actually worked for a little while this morning but then it started popping almost immedicately when the master was flipped.

 

any bets as to what the issue may be?  do the circuit breakers go bad, or is that unlikely?

[N33GG]

Some breakers do get weak with age, especially the ones with the big toggle switch.

Might not be the circuit breaker, but yes, they do go bad. Don't rule it out.

Good luck.

[Marauder]

Some breakers do get weak with age, especially the ones with the big toggle switch.

Might not be the circuit breaker, but yes, they do go bad. Don't rule it out.

Good luck.

I second this as well. Over the past few years I have replaced several pull type breakers because they were wearing out and popping. Find another breaker with the same rating and pull it. I could feel the difference between the good and bad one.

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[rbridges]

I'm not sure which I'm hoping for.  The circuit breaker looks like a major PITA to replace.

[N33GG]

Circuit breaker should not be that big of a deal to change. Many of them have screw terminals that make it extra easy, just depends on what you have in your aircraft. Like Marauder, I have had to replace several that have gotten weak over the past few years (landing light and transponder come to mind, just to name a couple). Of the possibilities, a bad circuit breaker is not the worst news you could get!

Again, good luck!

[rbridges]

Circuit breaker should not be that big of a deal to change. Many of them have screw terminals that make it extra easy, just depends on what you have in your aircraft. Like Marauder, I have had to replace several that have gotten weak over the past few years (landing light and transponder come to mind, just to name a couple). Of the possibilities, a bad circuit breaker is not the worst news you could get!

Again, good luck!

 

I've got the J style circuit breakers on the right side of the panel.  They look hard to remove, but I hope you're right.  I called the avionics guy and he's going to look at it next Monday.  Thanks for the help.

[N201MKTurbo]

If the switches have a buss bar, remove all the screws from all the switches and push them back as a unit. Then change the one switch on the buss bar and reinstall.

[Marauder]

I've got the J style circuit breakers on the right side of the panel. They look hard to remove, but I hope you're right. I called the avionics guy and he's going to look at it next Monday. Thanks for the help.

I would check all of them carefully and replace any suspect ones. Less headaches later on.

[N601RX]

Are the gauges the type that you can just remove one screw and unplug them? If so unplug all of them and see if it still pops the CB. If not then put only one at a time in and see if any particular one trips it.

[rbridges]

Are the gauges the type that you can just remove one screw and unplug them? If so unplug all of them and see if it still pops the CB. If not then put only one at a time in and see if any particular one trips it.

 

it looks (in my ignorant opinion) like it's a single hot wire that is daisy chained to each gauge.  

[rbridges]

If the switches have a buss bar, remove all the screws from all the switches and push them back as a unit. Then change the one switch on the buss bar and reinstall.

 

I'll pass that on.  thanks.

[N601RX]

it looks (in my ignorant opinion) like it's a single hot wire that is daisy chained to each gauge.

How about from the front side? On my F each individual gauge can be slid out the rack from the front side. The rack has sockets in the back that he gauges plug into. I'm not sure if the later models are like this or not.

[rbridges]

How about from the front side? On my F each individual gauge can be slid out the rack from the front side. The rack has sockets in the back that he gauges plug into. I'm not sure if the later models are like this or not.

 

 

I don't think so.  It looks like a solid strip.  

[MooneyCFII]

just started yesterday.  not a problem prior to that.  it's a 5 amp circuit breaker that connects to the instrument cluster strip.  mine has the J model strip, not that it necessarily matters.  I left a message for my avionics guy to call me.  In the meantime I was trying to find some answers.  I figure it's either a short or a failing circuit breaker.  I looked under the glare shield, and nothing jumped out at me.  The circuit breaker actually worked for a little while this morning but then it started popping almost immedicately when the master was flipped.

 

any bets as to what the issue may be?  do the circuit breakers go bad, or is that unlikely?

Yes, circuit breakers can go bad in that they will eventually trip at currents less than rated. That should NOT be the case with the gauge-cluster since its normal current draw is well under 5A. So even a breaker that is old and has reduced capacity should not begin to nuisance-trip with just the gauge-cluster as a load.

 

A key point here in your trouble shooting is that you said that the breaker would trip almost immediately. If you mean that you let it trip and then immediately reset it and it tripped again immediately, that is actually normal behavior for a good breaker. These are thermal circuit breakers and unless you let them cool down after tripping, they will trip off again almost immediately. OTOH, if you let the breaker cool down and then it tripped again almost immediately you are probably looking for a short-circuit somewhere. Examine the wiring bundle under the panel for wires that have chaffed against any of the metal structure. 

 

As for changing the breaker, the entire breaker assembly on the right side of the cockpit may be removed from the panel as a unit. You need to remove the glare shield and then disconnect the large Amphenol connectors that bring all the wiring to the breaker module. You will also need to unbolt the heavy cables that come from battery and alternator. Once you have the breaker module removed from the panel, changing the breaker itself will be a piece of cake. 

 

Oh, and of course you planned to disconnect the battery prior to working on the breaker module, right?

[rbridges]

Yes, circuit breakers can go bad in that they will eventually trip at currents less than rated. That should NOT be the case with the gauge-cluster since its normal current draw is well under 5A. So even a breaker that is old and has reduced capacity should not begin to nuisance-trip with just the gauge-cluster as a load.

 

A key point here in your trouble shooting is that you said that the breaker would trip almost immediately. If you mean that you let it trip and then immediately reset it and it tripped again immediately, that is actually normal behavior for a good breaker. These are thermal circuit breakers and unless you let them cool down after tripping, they will trip off again almost immediately. OTOH, if you let the breaker cool down and then it tripped again almost immediately you are probably looking for a short-circuit somewhere. Examine the wiring bundle under the panel for wires that have chaffed against any of the metal structure. 

 

As for changing the breaker, the entire breaker assembly on the right side of the cockpit may be removed from the panel as a unit. You need to remove the glare shield and then disconnect the large Amphenol connectors that bring all the wiring to the breaker module. You will also need to unbolt the heavy cables that come from battery and alternator. Once you have the breaker module removed from the panel, changing the breaker itself will be a piece of cake. 

 

Oh, and of course you planned to disconnect the battery prior to working on the breaker module, right?

 

wow, thanks.  I went back yesterday to do some other stuff and tested it again.  It trips as soon as the master is flipped.  I'm guessing a chaffed wire somewhere.   

[rbridges]

first the steering horn, and now the circuit breaker.  I guess my plane is following in your J's footsteps.  

[rbridges]

Hey, speaking of which. Have you flown your plane since having the steering horn overhauled? Did it solve your shimmy problem?

 

I think it has.  Probably had about 4 landings or so, and no shimmy during landings or taxiing.  Thanks again for the advice.