Electrical questions

Submitted: Friday, Nov 01, 2019 at 11:06
ThreadID: 139265 Views:777 Replies:1 FollowUps:13
I have had some electrical issues with my 12 volt MM air pump and would like some thoughts
The 12 volt 60 amp relay and or other components have failed somehow/ somewhere and I have decided to replace rather than sending back to manufacturer as no longer under warranty . Inside the cover on the negative the main wire is just twisted together with a cap not soldered why is this??
The other question is how good is this circuit breaker picture am I better with an different style or fuse similar
Cheers Nick b
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Reply By: Allan B (Sunshine Coast) - Friday, Nov 01, 2019 at 11:36

Friday, Nov 01, 2019 at 11:36
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Hi Nick,

Those connectors have been around for a long time, used to be porcelain but now plastic. They have an internal tapering thread and seemed to be reliable. They were cheap and fast for OEM's but I never re-fitted one just the same.

What is an "MM" pump. Is that the brand name?
I don't recognise the circuit breaker. Is it an auto-reset type or manual reset? Looks pretty solid.
Is the relay on the compressor or separate?
Is there a switch on the compressor?

Do you have a multimeter? If so I will give you some directions to troubleshoot.

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Allan

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Follow Up By: Member - nickb "boab" - Friday, Nov 01, 2019 at 19:51

Friday, Nov 01, 2019 at 19:51
MeanMother air compressor is the brand thks Allen & Manuel reset on the circuit breaker . It also had remote control on off .. I thought I would simply get a new 60 amp relay and on off switch and dispersal of all the other components keeping it simple
Formally it did have no power going to the on off switch but did had power to three terminals on the relay except the supply to the motor itself... maybe you might have some thoughts on why this may happen but obviously something not right


Cheers Nick b
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Follow Up By: Allan B (Sunshine Coast) - Friday, Nov 01, 2019 at 21:04

Friday, Nov 01, 2019 at 21:04
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OK Nick,

Does the relay click when the control switch is operated?
If yes, then the fault is either with the relay contact or with the motor.
If no, then the fault is with the control circuit.
From what you have said I suspect the control circuit including the remote.

Is the remote control a wireless type or a switch at the end of a long cable?
If wireless then your plan to dispense with it in favour of a simple switch/relay has merit.

Does your hose blow free air when disconnected from the tyre or does it shut off and a pressure switch stops the compressor? This affects the control modification considerations.



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Follow Up By: Member - nickb "boab" - Friday, Nov 01, 2019 at 22:38

Friday, Nov 01, 2019 at 22:38
Thanks allan....Wireless remote & pretty sure it doesn't switch off by it self , relay doesn't switch & has 12v power both sides of switch/trigger side of the relay . Regards connecting the negative wire what would the standard way of connecting these main wires ...
Cheers Nick b
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 02, 2019 at 00:10

Saturday, Nov 02, 2019 at 00:10
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Yes Nick, I can see why there is 12v positive both sides of the relay coil.
One side is permanently connected to 12v pos and you will also read 12v on the other side of the coil as the meter is seeing the 12v pos via the coil.

The small yellow wire leaving the board (in the "back side" photo) is the control for the relay. When this wire is pulled down to earth (negative) current can flow through the coil and energise it to run the compressor. If you were to connect a temporary wire from earth to the point on the board where that yellow wire connects then the relay should pull-in and the compressor run.

If that does not happen then either the relay or the motor is faulty. If the relay is OK then you should hear it click as you touch the earth onto the yellow wire. If the relay does not pull-in then it is faulty and should be replaced.
If the relay pulls-in but the motor does not run then either the motor is faulty or the relay has a burned-out contact.

If the the relay pulls-in and the motor runs then you could consider doing away with the remote control and simply permanently connect the earth to the relay in lieu of the yellow wire. The compressor could then be controlled by its existing switch. Remove the yellow wire from the relay to avoid false signals to the relay.

Your question "Regards connecting the negative wire what would the standard way of connecting these main wires"........ I don't follow you here. What "main wires" are you referring to and where are you intending to "connect" them?

Comment: I like simple engineering so I endorse your proposal to eliminate the remote control and use a simple switch. The motor could be controlled directly by a switch without using relay however it would need to be a 60A switch which are bulky and not so easy to come by. So a small (10A?) switch can be used to control a 60A relay. Still fairly simple.



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Allan

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Follow Up By: Member - nickb "boab" - Saturday, Nov 02, 2019 at 07:12

Saturday, Nov 02, 2019 at 07:12
Allan : the motor runs fine . I suspect the problem lays with the remote or the coil as there is no power at the switch at all , or maybe the switch , switch the earth ?
I will try what you have suggested & see what happens.
Regarding my question on connecting the main cable , that was referring to the yellow twist cap connector in the original picture where you said you would not replace that style of connector. would you simply solder it ? This is the negative wire out of the pump motor connecting to negative wire going to the battery .
Cheers nick

Cheers Nick b
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 02, 2019 at 10:04

Saturday, Nov 02, 2019 at 10:04
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Nick, good that the motor runs OK. Your photos do not reveal the "switch" so I cannot be sure how that is arranged. However I can clearly see that the relay coil is connected on one side to positive on the circuit board and is controlled by taking the other side down to earth by the yellow wire. This may be the reason why you are not seeing "power" (positive) at the switch. It is switching the negative. The remote control is also connected in this "yellow wire" circuit which may be playing a part in your voltage observations.

If the relay is OK and you wish to dispense with the remote control then your easiest path is to simply remove the yellow wire at its end away from the circuit board (leaving it connected at the circuit board) and connect the freed end to a switch with the other side of the switch connected to negative. Retain the circuit board with its relay and retain the aforementioned switch. Everything else related to the original control circuit may be removed including the small red and black wires connected to the circuit board leaving only the thick black wire, the two thick red wires and the newly allocated yellow wire.

I am curious about the device on the circuit board circled in blue in my photo below. Do you know what that is?

Re that yellow twist connector.... if it has not been undone then I would leave it alone. Properly applied they perform OK. But if you have removed the yellow connector then maybe it would be best to simply solder the wires and inflate them. Those twist connectors can be tricky to apply correctly. Left alone they are usually OK but when I have had need to remove them I have always applied a different means of junction.



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Allan

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Follow Up By: Member - peter_mcc - Saturday, Nov 02, 2019 at 12:18

Saturday, Nov 02, 2019 at 12:18
It's a bit hard to see from the photos but I think the circled yellow thing is a common mode choke to reduce noise from the compressor motor/brushes. The 12V positive side appears to go through it then to the relay then out. I can see a thick black wire connected to it as well but there is a thumb in the way to see what is on the other side.

It is unlikely to fail - if you want to check it turn the power off and measure across it with a multimeter (it has 4pins, 2 sets of coils on the same magnetic core) - it should have very low resistance.
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Follow Up By: Zippo - Saturday, Nov 02, 2019 at 12:23

Saturday, Nov 02, 2019 at 12:23
Allan, you've been hit by the auto-correct gremlin: "solder the wires and inflate them."
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 02, 2019 at 12:42

Saturday, Nov 02, 2019 at 12:42
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No, "inflate" was correct Zippo. I run all my soldered joints at 35psi. lol
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Allan

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Follow Up By: Zippo - Saturday, Nov 02, 2019 at 13:09

Saturday, Nov 02, 2019 at 13:09
On sealed roads maybe, but far too high for off-road ;-)
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Nov 02, 2019 at 19:08

Saturday, Nov 02, 2019 at 19:08
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Yes,. I think you're right Peter. And that would be appropriate too.

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Allan

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Follow Up By: Member - nickb "boab" - Sunday, Nov 03, 2019 at 06:10

Sunday, Nov 03, 2019 at 06:10
hopefully bit more clearer
Pretty much as you have said fault is in the remote
So keeping it simply & hopefully reliable
I have replaced the relay & switch with new components .... works like new
Thanks for your input.
Cheers Nick b
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Follow Up By: Allan B (Sunshine Coast) - Sunday, Nov 03, 2019 at 10:01

Sunday, Nov 03, 2019 at 10:01
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That's great Nick. Happy to help.
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Allan

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