Master switch wiring help

iRideKTM

iRideKTM

Non-Member
Hey all, yesterday I was troubleshooting my master switch not working in the Spare side and have a question about the extra wiring on the left (looking forward with switch lever pointing forward) contacts of the switch. Does anyone know what it goes to? I have a 1955 Tri-Pacer so before a starter solenoid was added so I have the always hot starter in the same box. I'd like to convert the switch to a circuit breaker because I can tell it's on its last leg (corrosion around the gaps so I'm thinking it's quite rusty inside) but since I don't know what exactly the extra wiring does I don't know what to do with it. The POH I have has the schematics for a solenoid equipped Tri-Pacer so I'm not sure if it's accurate for my system. If I do go to a circuit breaker, what size is everyone installing? The POH shows 30 amp fuses which matches what's installed but I do have the Plane Power alternator installed so I figure the wiring is the limiting factor now which is the original cloth wrapped type.
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Most people think that Svenn’s STC is just for the lightweight battery. It also has the approval for a resettable master and relocates the starter switch. I replaced the old double pole double throw AN switch. The STC also has wiring drawings for adding a master solenoid and starter solenoid. Checkout the attached wiring for how I did it. In the process I added warning lights and powered them from the buss bar between the solenoids.
 

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Are the extra wires for the old generator field? Alternators use battery voltage to F1 on the VR. Another good reason to upgrade.
 
On second thought it looks like someone added a single breaker for the original two glass fuses. That is why one side of the switch does not work. So your battery is going thru the DPDT master and the single breaker. Has The wiring has been left unconnected and the fuse bar removed?
 
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Vagabondblues said:
On second thought it looks like someone added a single breaker for the original two glass fuses. That is why one side of the switch does not work. So your battery is going thru the DPDT master and the single breaker. Has The wiring has been left unconnected and the fuse bar removed?
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There is a breaker but it’s for the alternator field. I think you’re right about someone leaving the old field wiring in place and just using one of the original wires to go back to the new alternator. It was installed before I owned the plane so looks like I have a bit of digging to do. After being under the panel for a bit yesterday, I can tell this plane will lose 10lb after I clean up all the junk wiring that was left over the years.
 
Here is what that looked like before it was basterdised
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Hopefully I'll get a chance to run out this weekend and verify the two smaller wires are indeed leftovers from the old generator and voltage regulator setup and useless. If thats the case I'll probably order one of the Tyco lever CBs and call it a day. Boy do I really want to start gutting the old cloth wiring but it's probably better to wait til I have another reason to get crazy under the panel.
 
iRideKTM said:
Hopefully I'll get a chance to run out this weekend and verify the two smaller wires are indeed leftovers from the old generator and voltage regulator setup and useless. If thats the case I'll probably order one of the Tyco lever CBs and call it a day. Boy do I really want to start gutting the old cloth wiring but it's probably better to wait til I have another reason to get crazy under the panel.
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Yep, resettable circuit breaker switch eliminates the need for glass fuses and double pole switch. Some will say not "approved" but I would check the ICA paperwork for your plane power alternator.

Piper in the eighties started to run all the grounds to a terminal block with 6 studs. They would lay a bonding strap over all of the studs and then attach one bonding strap to the firewall or engine mount bolt. I used this gang grounding on my Pacer. Eliminated all the spaghettis. I also made it so I can pull out the electrical "glove boxes". Spent a lot of time upside down with my ears between rudder pedals running wire. Or pull the bootcowl, you will have all the room you need.

one of the pics was my inspiration for the back of the panel
 

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iRideKTM said:
There is a breaker but it’s for the alternator field. I think you’re right about someone leaving the old field wiring in place and just using one of the original wires to go back to the new alternator.
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The Tyco c/b toggle combo switches dont have a real good rep, short life span, talk about spaghetti look inside one of those tyco switches, you will see the weak points. I would use a toggle and stand alone c/b.

It looks like what they have done is put a c/b in place of your 30 amp fuses, the breaker in your picture with the new white wires is that a 30 amp c/b?

I like the original 30 amp fuse setup, works fine last long time, thats what my 16 has the pic I posted is my plane. Where is the alternator c/b you mentioned?
 
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The current CB in the box is a 5 amp for the alternator field and it's fed from the center post of the master switch so any time it's on, the alt field gets power. I wouldn't mind replacing just the switch but I'm having a hard time finding a switch that can carry 30 amps, everything I've found so far on ACS is 20 amps or less. I have browsed Amazon in desperation but I can't find anything that can carry higher current that isn't some chinese no-name company. I'd be ok with going to a SPDT switch if I don't need that jumper setup installed but that still leaves me in a bind as far as high amperage switches go. I'd hate to have a situation where the switch became the inadvertent "circuit breaker" under a high draw situation. At work, we use the standard milspec pullable CBs on everything in helos, those things get pulled after every flight and I can honestly count on one hand how many I've replaced due to internal failure over the last 15 years. I'd be good picking up one of those and using that as a master switch.
 
Guidance in 43.13 shows a chart that when replacing a 30 amp fuse with a circuit breaker, the circuit breaker should be rated at 40 amps. I would make sure the wiring is also rated for that higher load.
N2709P
 
Ok, you just dont have enuf info there in those pics. I see the new white wire from the breaker going to the center term of the right side of the master, so the outer terminals must be jumpered together and go to the alternator?

I dont see anything Fuse or c/b for the battery to master protecting with 30 amps, dont see anything connected to the center term of the left pole? How is that left pole powered?

.
Factory setup

Upper Pole=30 amp fuse block wires, one on each outer terminal, center termianal to Ammeter than main bus

Lower Pole=field for GEN, outer terminals jumped together, field source GEN coming to left terminal, center terminal to Volt Reg to power up Gen
.
.
attachment.php


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I would use a 30 amp breaker and a toggle, or stick with the 2 fuse setup, I have had my plane 10 years and never popped a 30 amp fuse.
 

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This is the best picture I have for now. Only thing not in the pic is the fuse block. The 2 big wire pigtails are the “inputs” for the master switch from the fuse block then the center right post has a wire going to the main buss. Also on that same terminal is a smaller wire going to the 5 amp breaker dangling there that gives the alternator it’s exciter field power. The left posts have wires going to them but nothing on the center left post which is leading me to believe the mechanic that installed the alternator decided to be lazy and leave the “jumper” circuit for the old generator in place.
IMG_5902.jpeg
 
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Ok, think I understand, left side of switch not being used sounds like, put a voltmeter on and see what you have on terminals to confirm. Right side you have a 30 amp fuse blown thats why only one side works, or bad connection.

Your Alt field is the center terminal fed by either outer terminal.... so your Alt must be inop when you select the non powered outer terminal?

I would not change a thing other than pull the old wires off the left side of the master. What is corroded?
 
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The switch has corrosion around where the housing of the switch meets the faceplate of it so I suspect the inside isn't in a very happy place. As far as I can tell, it's original so I can't be mad at a 70 year old switch finally high-timing. I did find some high amp switches available so I'll probably order one once I know whether I need a SPDT or DPDT.
 
An expensive switch, might just get a battery solenoid and that 30 amp c/b along with a simple on off toggle.
 
PA-16 said:
An expensive switch, might just get a battery solenoid and that 30 amp c/b along with a simple on off toggle.
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I found 2 that are $10 for the SPDT and $16 for the DPDT so will probably go that route based on what I find when I read the wiring out. I don't have a problem with the fuses but I would like to look at relocating the fuse block to the lid in an effort to make changing them on the go easier.
 
PA-16 said:
The Tyco c/b toggle combo switches dont have a real good rep, short life span, talk about spaghetti look inside one of those tyco switches, you will see the weak points. I would use a toggle and stand alone c/b.

It looks like what they have done is put a c/b in place of your 30 amp fuses, the breaker in your picture with the new white wires is that a 30 amp c/b?

I have had those Tyco switch/ckt breakers in my airplane for23 years with zero failures.

I like the original 30 amp fuse setup, works fine last long time, thats what my 16 has the pic I posted is my plane. Where is the alternator c/b you mentioned?
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I have had those switch/ckt breakers for 23 years in my airplane with no problems.

89c2ec9b-2aa8-497b-aa4a-347b07c8ecd8
 

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PA-16 said:
The Tyco c/b toggle combo switches dont have a real good rep, short life span, talk about spaghetti look inside one of those tyco switches, you will see the weak points. I would use a toggle and stand alone c/b.
Click to expand...
I have rebuilt 5 Super Cubs and redone a lot of instrument panels using the Tyco CB switches. Out of all those switches I have had one get weak. I like to simplify the system, one part replaces two. Has worked great for me.
 
Vagabondblues said:
Yep, resettable circuit breaker switch eliminates the need for glass fuses and double pole switch. Some will say not "approved" but I would check the ICA paperwork for your plane power alternator.
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Common hardware, can't imagine an FAA inspector having an issue with a CB vs a glass fuse. Is not an electrical system design change.
 
They look exactly the same to me, please clear this up, I, as well as others here are probably not clear on which toggle circuit breaker switch is bad and which one is good. Several people have had failures and the FAA issued an AD and SB about them.
 
Pretty obvious from the photo and I didn't bother looking up your part number. I find no AD on the Tyco part number I showed and have been using.
 
Steve Pierce said:
Pretty obvious from the photo and I didn't bother looking up your part number. I find no AD on the Tyco part number I showed and have been using.
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It does not look obvious to me, can you point out what I am missing. The switches look identical to me except the AD one has been opened up, the one you posted linked at Spruce is not opened up.
 

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The AD is for a Tyco W31 switch, its confusing to me which W31 is the bad one and which is the good one.
 

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