Master Relay

[bnicolette]

My mechanic was wiring in the power receptacle which will reside in the hat shelf.  Apparently one of the studs on the master relay sheared off somewhat.  He was able to "rig" it so that it is working just fine but I am not crazy about that word "rigged".  I haven't seen what he's talking about yet and am thinking of just replacing the relay if when I see it am not crazy about the setup.  Anyhow, can someone steer me in the right direction for the proper relay and where to get it?

1982 M20J

It is the relay that resides next to the battery box and receives a wire straight from the battery.

[thinwing]

Master relays are pretty generic parts but I would call an msc or note to Stacy at factory for part # and availbilty than a call to aircraft spruce or chief aircraft..I have a few relays hanging arround my hanger even...an of course your mechanics repair maybe completely airworthy..have you looked at it yet??

[bnicolette]

I haven't seen it yet but my mechanic is very meticulous so it's probably fine.  I just thought if the cost wasn't out of line I may just go ahead and replace it.  I got a price of approx $275 from a MSC but didn't ask for the part #.  I don't exactly remember what the relay looks like but I thought that it was just an ordinary relay?  Like this:

https://www.aircraftspruce.com/catalog/elpages/masterrelay.php?clickkey=3575

 

But for $275 I guess maybe there is more to it?

[bumper]

Master relays for experimental aircraft are available from McMaster-Carr (part #7995K11 for 80 amp rated for $25? or part #7995K31 for 200 amp rated for $55? ). Also available at NAPA auto parts etc. - - commonly used on golf carts.

 

On Amazon: http://www.amazon.com/PAC-PAC-200-200-Power-Relay/dp/B000CEBXRS/ref=sr_1_2?ie=UTF8&qid=1373417968&sr=8-2&keywords=12+volt+heavy+duty+relay#productDetails

 

 

Make sure to use a "continuous duty" version and one that is rated for the expected current flow. Typical SPST (single pole single throw) NO (normally open) relays have either 3 or 4 terminals. Those with 3 terminals will have one side of the coil connected internally to one of the  relay contacts. The relay will be activated when the small terminal is connected to the opposite polarity as the relay is switching (e.g. if the relay is switching positive, then it will be switched on by applying ground to the small 3rd terminal). 

 

4 terminal SPST relays can be used in place of 3 terminal versions by simply connecting one of  the small terminals to a large input terminal externally.

 

bumper

[tony]

I'm not sure of the relay that you have on your J, but here is the drawing to the relay that's on my F model.

6041H231.pdf

[FlyDave]

Brett,

 

I have a 1982 J also. I looked in the electronic copy of the J model parts manual but it didn't have a part number.

I'll be going to my hangar tomorrow and I'll look in the printed parts manual for a part number for it.

 

Dave

[bnicolette]

I was able to get to the airport today and see what was happening with my airplane and get the part # for the relay.  Everything looks good to me and I'm not going to replace it.  But if I were, is there a cheaper alternative than going with the $275 unit?  

[bnicolette]

I just found an old post about this relay.  It appears as though there is a new version available.  Part # 6041H105 and is made by Eaton.

 

http://mooneyspace.com/topic/3437-spec-sheet-for-cutler-hammer-6041h231/

[jetdriven]

here is some info:  http://mooneyspace.com/topic/3437-spec-sheet-for-cutler-hammer-6041h231/

 

 

and if you can get your mechanic to agree it is a "standard part" (It has no TSO, PMA, or Milspec) and the 6041H105 meets or exceeds the original specs, then the 6041H105 may work.

[Marauder]

Another reason to fly experimentals... http://www.aircraftspruce.com/catalog/elpages/masterrelay.php You can get it for $30 for experimental usage. I will look to see if there are certified sources for you. My guess, the price you were quoted is the certified version.

 

This is a SPST (single pole single throw) 12VDC relay. Part number is 6041H231.

[jetdriven]

There's no PMA or TSO, like a transitor in your panel light box. If you can get the specs of a standard part, like a belt, bulb, transistor, or relay, then you can use it under the FAA's aging aircraft program.

[Marauder]

I agree with Byron. As long as it isn't part of the "certified" regiment, you should be able to substitute if it is equivalent in performance specification. I looked for the "105" version and didn't see anyone who actually is selling it. I will keep looking.

[Marauder]

Hmmm.... none of my normal sources (Mouser, Allied, Grainer, Newark Electronics) carry it. Here is what I found:

 

http://www.peerlesselectronics.com/store/search.php?search_query=6041H105+++++&x=0&y=0

 

http://www.ralphselectronics.com/SearchResults.aspx?criteria=6041H105

[bnicolette]

Yikes Chris.  Ralph's really marked that puppy up.  $505    Thanks for looking.  I don't plan on replacing it yet and it appears as though all is well and my mechanic says it's fine and no issue.  I was just trying to get ready incase the thing fails.

 

Thanks everybody for the information!

[Marauder]

You're welcome Brett. I went to one of our procurement directors and asked if they could check out how much we could get these for. He came back and said that If we bought a minimum of 1000 we would get a good price. LOL!

[NWMooneyDude]

So, with regards to the old style relay 6041H231 I have a question....

 

Our '81 J recently had an electrical issue where a ground short smoked the jumper cable between the two smaller terminals on the master battery relay. (Old style H231)

 

The wiring diagram depicts a diode between these terminals, but I haven't had much luck locating a part number or spec for the diode......

 

Does anybody know if the newer style relay, H105, requires this same jumper w/diode, or could it have possibly been build into the newer design?? Or does anyone have any info on the diode I'm referring to on the master relay?

 

Any help is greatly appreciated!

[N601RX]

The diode is across the coil. The diode is reverse biased in the circuit when the master switch is turned on so the diode is turned off and no current flows through it. Without the diode, When you turn the master switch off the field in the coil collapses and you get a large reverse voltage across the coil. The diode is now foward biased and the reverse voltage is shorted out throgh the diode and doesn't go back into other aircraft circuits. Without the diode it will eventually burn the contacts up in your master switch and possibly damage electronics in the plane. Newer avionics are protected from this, but some handheld stuff may not be.

[NWMooneyDude]

Great info! Thank you.

 

I believe the part number and specs for the diode are in a MAC drawing that I do not have. (The wiring diagram for the airplane only shows that a diode is present, not its specifics)

 

Tomorrow I'm going to call MAC Tech Support and attepmt to get a PN, or at least some of the specs.

[larryb]

The specs on a diode in this application are not critical at all. Any diode with a reverse voltage > 50v and current >= 3 amps should be fine. Here's one for $0.23. The end with the white band goes to the + side of the coil.

 

http://www.alliedelec.com/search/results.aspx?term=70061741

[NWMooneyDude]

I was able to get a quick reply (email) from MAC Tech Support, and the diode across the master relay for our '81 J is a 1N2483. Alternate IN5060 or GE3720.