Bad New Master Solenoid?

I haven't even flown yet, but my Vans-supplied master solenoid failed the other day when I was about to load some software updates to my Dynon Skyview system. You could hear the click, but there wasn't any current coming out of the solenoid. The Vans unit had been failing intermittently for some time, so this wasn't a huge surprise. So, I thought this is a good time to buy a new, quality solenoid and I went ahead and spent over $60.00 on a new Lamar X61-0028 from ACS.

While waiting on some resin to cure today, I thought I'd install the new solenoid, which I proceeded to do. When I hit the master switch, nothing happened...I'm thinking huh? So, I removed the solenoid and bench tested it, which I should have done in the first place. It failed and I am having a hard time believing that a new, out of the box unit wouldn't work, and so I am putting this out for comments.

Here's a photo of the unit:



A is connected to the + terminal of the battery, B is connected to terminal A with a 20 ga wire, C is connected to the master switch (which is connected to ground when the switch is turned on) and D is connected to the load. As I understand it, this is a conventional set up.

When I had the unit on my bench, I connected A to the positive terminal of my 12v power supply, and I connected the - terminal of the power supply to C, and a click was heard. When I tested the dc volts between A and C, I got 13.6 volts, which is exactly what I would expect. When I tested the dc volts between C and D, I should have gotten 13.6 volts, but I got nothing. When I checked continuity between A and D, I got nothing where I should have gotten continuity.

I'm no electrical wizard, but my understanding is that the B and C terminals simply activate the solenoid, which just bridges terminals A and D. Stone simple.

So, am I missing something (wouldn't be the first time) or did I buy a bum unit?

What are you using for a power supply?

guido99 said:

What are you using for a power supply?

Click to expand...

A Radio Shack 13.8V 19a DC power supply

poor battery ground connection?

I just went through this. I thought I had a bad master solenoid because it wouldn't go "clunk" when I turned the master switch on. When I flipped the master switch, I got nothing....no clunk, nothing, just blackness on my screens.

So, I put on a new master solenoid, hit the master switch and got nothing....

I finally tracked it down to the terminal connection where my battery grounds to the airframe. The connection looked good, and has worked as it should for several years.

Long story short, I cut off the terminal, recrimped with a new terminal, reconnected it to the airframe, and everything started working as it should.

Try connecting the relay to a 12 volt battery.
Power supply may be your problem.
Seems very unlikely you have 2 bad relays

When you installed the Van's unit, did you take care not to rotate the copper lug when connecting the cables to A and D?

Torquing

Be careful torquing the nuts, be sure to hold the inside nut with a wrench when you torque the outside nut. If the stud turns the contractor will become trash.

gasman said:

When you installed the Van's unit, did you take care not to rotate the copper lug when connecting the cables to A and D?

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Since the contactor worked for many months prior to it failing, I don't think I rotated it.

bhester said:

Be careful torquing the nuts, be sure to hold the inside nut with a wrench when you torque the outside nut. If the stud turns the contractor will become trash.

Click to expand...

On the new contactor, being very aware of this issue, I had just given the nuts a nominal tightening for testing purposes. The Lamar contactor allows up to 45 in-lbs for the main lugs, and I'm sure I wasn't anywhere close to that

guido99 said:

Try connecting the relay to a 12 volt battery.
Power supply may be your problem.
Seems very unlikely you have 2 bad relays

Click to expand...

In the plane, I have a PC680 and it's in good shape. The contactor has been tested with both the battery and the power supply. It shouldn't matter anyway, 12VDC is 12VDC.

Mark
I won't get into the specifics but I can tell you that 12 V from a power source is not always the same as 12 V from a battery.
Have you removed all the wires and checked continuity thru the solenoid coil and across the contractor?
Then power the coil directly and check continuity across the contractor.
I would use a good battery to power the coil.
Good Luck
Guido

I pulled the battery out of the plane and set up the test as shown here:

Before connecting anything...



After connecting and hearing the "click", measuring current from input and ground:

12.3V, battery is a little low from all the testing



Then switching to the other side:

0.0V...nada



Finally, testing for continuity, nada....nothin'



Am I doing something wrong or is the quality of the brand-new, top of the line, carefully tested (according to the ACS website anyway), new out of the box contactor "suspect"? Methinks it's no good.

Are you sure you got the 12v unit not the 24?
I would remove power from the main lug when testing continuity.
Try it with a lamp and see what happens,

Walt said:

Are you sure you got the 12v unit not the 24?
I would remove power from the main lug when testing continuity.
Try it with a lamp and see what happens,

Click to expand...

Yep, it's the X61-0028 marked 12V.

Here's the result of the continuity test with power removed from the main lug:



And here's the result of the continuity test on the coil:

That may be a mismarked 28v solenoid. According to spruce's data sheet, a 14V united coil resistance should be 14.5 ohms and a 28V unit should be 54 ohms.

Looks like a bad contactor to me.

Yes, I think both of those conclusions are feasible. I don't have a 24v supply to test with, so it's going back to Spruce tomorrow.

FYI

My first question was the "circuit" of the contractor. In case anyone was thinking the same, here is a cartoon of the internal circuitry. You can tell what reference to the coil resistance means.

4-post Contactor

Weird timing!

I bought one of these about 6 months ago to replace a marine style battery switch I had been using. It worked great for about 5 months, then it would 'clunk' when activated, but when I tried to start the plane it seemed like I had a dead battery. Well, I had good voltage, so I cycled the solenoid 3 or 4 times and the plane started right up. Got another one. Maybe they're having a having a run of bad ones...

BillL said:

My first question was the "circuit" of the contractor. In case anyone was thinking the same, here is a cartoon of the internal circuitry. You can tell what reference to the coil resistance means.

4-post Contactor

Click to expand...

Something as simple as this you might think could be built like a tank and 100% reliable, but nooooo....

Bad relay

Just went thru 4 bad relays while replacing a set of three on a Stearman. I finally purchased a Skytech set for his bird. If you're getting the relay to close outside if the airplane using the battery I'd look at my wiring and possibly the switch as the issue. I replaced a bad relay on a Bonanza last month as well. 36 years in doing maintenance I've never seen so many relays go bad in such a short time.

jim plaster said:

Just went thru 4 bad relays while replacing a set of three on a Stearman. I finally purchased a Skytech set for his bird. If you're getting the relay to close outside if the airplane using the battery I'd look at my wiring and possibly the switch as the issue. I replaced a bad relay on a Bonanza last month as well. 36 years in doing maintenance I've never seen so many relays go bad in such a short time.

Click to expand...

I wonder if Skytech is just a relabeled Lamar, Cole Hersee, or White Rodgers. It's hard to imagine that they actually manufacture their own solenoids. To me, that would be like making your own hammer!

Battery Connection Photo

In your first post you say "A is connected to the + terminal of the battery". Maybe I'm looking at this wrong, but in your battery connection photos is the + terminal of the battery connected to terminal D?

John Tierney said:

In your first post you say "A is connected to the + terminal of the battery". Maybe I'm looking at this wrong, but in your battery connection photos is the + terminal of the battery connected to terminal D?

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With this kind of contactor (as opposed to the three terminal variety), it doesn't matter which side is connected. Terminals A and D current flow can go either direction, and same with the coil terminals (B and C). Usually the + side is connected to one of the coil terminals with the master switch (connected to ground) is connected to the other, so that when you throw the master switch, it connects the coil to ground and since the other side of the coil is connected to the plus side, it activates the solenoid.

Mark - what you are experiencing is not commonplace, but also not unheard of. One test you can perform is non-destructive if done properly... Take your solenoid, go find a nice piece of 2x4 or similar, hold the solenoid in your hand and move it sharply downward so it goes "thunk" against the 2x4. I haven't seen this in the cheaper solenoids we currently use in our homebuilt airplanes, but I've seen it with the $$ MIL-SPEC solenoids in certificated aircraft, where the contactor would get hung up mechanically in the "open circuit" position, thanks likely to having been jostled in shipping/handling. That good thunk you've given it will sometimes cause the contactor internals to become un-stuck.

It's a slim chance this is the case, but it's still possible.

Canadian_JOY said:

Mark - what you are experiencing is not commonplace, but also not unheard of. One test you can perform is non-destructive if done properly... Take your solenoid, go find a nice piece of 2x4 or similar, hold the solenoid in your hand and move it sharply downward so it goes "thunk" against the 2x4. I haven't seen this in the cheaper solenoids we currently use in our homebuilt airplanes, but I've seen it with the $$ MIL-SPEC solenoids in certificated aircraft, where the contactor would get hung up mechanically in the "open circuit" position, thanks likely to having been jostled in shipping/handling. That good thunk you've given it will sometimes cause the contactor internals to become un-stuck.

It's a slim chance this is the case, but it's still possible.

Click to expand...

Too late, it's off to Spruce with a replacement on its way from Lamar. If I have the same problem with the new one, I'll try that though. I think I'll go give the old Vans solenoid a good thunk and see what happens!

Mark Dickens said:

Too late, it's off to Spruce with a replacement on its way from Lamar. If I have the same problem with the new one, I'll try that though. I think I'll go give the old Vans solenoid a good thunk and see what happens!

Click to expand...

Winner, winner, chicken dinner! I go out to the workshop, dig the Vans contactor out of the trash, give it a couple good whacks on the workbench and whaddya know? It works now!

I guess I should have learned something from watching my Dad give our old TV a good whack every now and then way back in the '60s, especially since these solenoids are of the same or older vintage design. Since the new solenoid is on the way, I'll keep the Vans as a backup. I learned something from this!

Cole Hersee

I have had bad luck with the Lamar products and now use the Cole Hersee p/n 24115 for the battery contactor and the Cole Hersee p/n 24037 or 24021 for the starter contactor and they seem to be much better quality. FWIW

Ain't science wonderful!

Mark Dickens said:

Winner, winner, chicken dinner! I go out to the workshop, dig the Vans contactor out of the trash, give it a couple good whacks on the workbench and whaddya know? It works now!

I guess I should have learned something from watching my Dad give our old TV a good whack every now and then way back in the '60s, especially since these solenoids are of the same or older vintage design. Since the new solenoid is on the way, I'll keep the Vans as a backup. I learned something from this!

Click to expand...

I'm glad to hear that "percussive maintenance" did the trick for you, Mark!