Accessing breaker panel

[Vaughn]

I have a M20F and want to inspect my circuit breakers, making sure the connections are good. How do I pull the CB panel?

[DCarlton]

29 minutes ago, Vaughn said:

I have a M20F and want to inspect my circuit breakers, making sure the connections are good. How do I pull the CB panel?

I have a 67F.  My CBs are mounted to the lower part of the panel on the left and right sides.  There's nothing to pull.  I believe there's buss bar that ties them all together but they're individually mounted to the panel.  I'm no expert though.  Your F is a later model?  

[N201MKTurbo]

Take all the panel nuts off of the circuit breakers and pull all of them back out of the panel together. The easiest way by far.

[ArtVandelay]

The J has 2 external screws holding the CB panel, is the F different?

[carusoam]

The CBs for 60s Mooneys come in from behind the instrument panel...

They are locked together by the bus bar at the back...

To set them free requires removing the nuts at the front...

 

 

Access to/from the back is pretty easy...  if young and acrobatic... or have access panels at the top of the cowl...

PP thoughts only... pics of what you have always help.

Best regards,

-a-

[Yetti]

What year F?

A cell phone camera will work best on all models.

[Vaughn]

It's a 1969 M20F... I'll post some pics later this week when I'm out at the hanger.

[Vaughn]

Here’s a picture of the cb panel. I looked at both the parts and maintenance manuals for some clue but didn’t have any success. Thoughts on how I may pull the breaker panel to inspect the connections?

[N201MKTurbo]

The panel has screws at the top and bottom. There are a zillion wires. The easiest way is to remove the gauges, then remove the panel nuts from the circuit Breakers, push them back a row or two at a time and swing them into the gauge holes for inspection or replacement. Removing the whole panel is a real PITA.

[N231BN]

Three screws on top, three underneath, two on the outside and the whole panel slides back. It depends on how thoughtful other mechanics were when adding wires for additional equipment. I can get mine back about 5-6 inches which is enough to work on the CBs.

[PT20J]

2 hours ago, N231BN said:

Three screws on top, three underneath, two on the outside and the whole panel slides back. It depends on how thoughtful other mechanics were when adding wires for additional equipment. I can get mine back about 5-6 inches which is enough to work on the CBs.

I think that’s as far as they come out. It seems Mooney built the plane around it. Mine comes out the most if I disconnect the tach and MP gauge. I think to access some of the breakers you probably have to take all the nuts off them to remove the panel. I haven’t had to do that so far.

BTW, the M20J service manual says that some years Mooney used rivets instead of screws on the exterior fastenings. That would just add to the fun.

Skip

[kellym]

3 hours ago, Vaughn said:

Here’s a picture of the cb panel. I looked at both the parts and maintenance manuals for some clue but didn’t have any success. Thoughts on how I may pull the breaker panel to inspect the connections?

 

Why do you think you need to inspect the connections? Is there an existing problem or are you trying to create one?

Kelly

A&P/IA

[EricJ]

Your glare shield should be removable, which will allow some access from the top with either a mirror or a cheapie USB endoscope.   On my J I can see a fair amount just by sticking my head under there and looking up, especially if the glare shield is off to let more light in.    A cheapie USB endoscope is your friend for stuff like this.

https://www.amazon.com/s?k=USB+endoscope

 

[Vaughn]

17 hours ago, kellym said:

Why do you think you need to inspect the connections? Is there an existing problem or are you trying to create one?

Kelly

A&P/IA

There's an alternator whine and the A&P suggested checking CB connections, already checked alternator ground.

[Yetti]

13 minutes ago, Vaughn said:

There's an alternator whine and the A&P suggested checking CB connections, already checked alternator ground.

Alternator wine is a diode has gone bad.   You can by diode pack for the alternator for like $10

Someone @jetdrivenhas a cross reference on diode packs that will work.  Get model number of alternator. 

Your noise filter may also be out.  Starboard firewall under cowl.

Edited June 6, 2021 by Yetti

[Yetti]

But it is kind of funny to think that someone would think that a CB or loose connection could cause a whine.   Loose connections cause sparky arky smoky bad things.

 

But I did have one.  But it was down low so I undid the breakers from the panel.    If you are looking at the Alt CB you can just take the glareshield off since it is up at the top.

 

[EricJ]

1 hour ago, Vaughn said:

There's an alternator whine and the A&P suggested checking CB connections, already checked alternator ground.

I think that'd be the last place I'd check for fixing alt whine.   A loose/corroded breaker connection might cause issues with whatever device(s) were connected to that particular breaker, but it probably wouldn't be a whine.

 

[carusoam]

+1 for alternator related, rpm dependent, whine, in the audio system...

So... if hearing a whine that changes with rpm...

Start by finding the bridge of diodes that turns the alternators ac output into dc current...

At least one of those things probably has indications of failure.... 

It may even be a visual thing...

PP thoughts only, stuff I have read around here...

Best regards,

-a-

[Vaughn]

On 6/6/2021 at 11:56 AM, Yetti said:

But it is kind of funny to think that someone would think that a CB or loose connection could cause a whine.   Loose connections cause sparky arky smoky bad things.

 

But I did have one.  But it was down low so I undid the breakers from the panel.    If you are looking at the Alt CB you can just take the glareshield off since it is up at the top.

 

I’m doing that first before creating more problems!

[Vance Harral]

On 6/6/2021 at 9:56 AM, Yetti said:

But it is kind of funny to think that someone would think that a CB or loose connection could cause a whine.

On the contrary, this is a completely reasonable guess.  Over our years of ownership we've had two "alternator whine" incidents that were not solved by noise filters, or even replacing the alternator.  In both cases the culprit turned out to simply be a loose ground wire.  Always check the wiring connections first.  It's tedious, but cheap, and absolutely can be the cause of various types of audio noise.

[EricJ]

Just now, Vance Harral said:

On the contrary, this is a completely reasonable guess.  Over our years of ownership we've had two "alternator whine" incidents that were not solved by noise filters, or even replacing the alternator.  In both cases the culprit turned out to simply be a loose ground wire.  Always check the wiring connections first.  It's tedious, but cheap, and absolutely can be the cause of various types of audio noise.

There shouldn't be any ground wires connected to the breakers in the breaker panel, though.   At least I'd hope not.   

[Yetti]

17 hours ago, Vance Harral said:

On the contrary, this is a completely reasonable guess.  Over our years of ownership we've had two "alternator whine" incidents that were not solved by noise filters, or even replacing the alternator.  In both cases the culprit turned out to simply be a loose ground wire.  Always check the wiring connections first.  It's tedious, but cheap, and absolutely can be the cause of various types of audio noise.

Bad ground or ground loop will usually manifest itself as a hum or buzz.  That may or may not change with the engine RPM unless it is an ungrounded mag.

[Vance Harral]

The point is that loose connections of any type (ground, power or signal), at any location, can cause audio noise.  As Yetti says, they "may" (or may not) change with engine RPM.

I'll say it again.  Check for loose wiring first.  It's tedious, but cheap, and absolutely can be the cause of various types of audio noise.  It's as good a place to start as any.

[cferr59]

If I thought the breakers or something connected to them were causing audio noise, I would pull them one by one to see if the noise stops.  Also, just try turning things off in general to see if you can get the noise to stop. 

[Yetti]

here is an interesting one that I did not know till installing the dynon. There is enough noise in the P Leads that you use them for an electronic tach.   With a resistor inline to settle some of the noise.