Results 1 to 7 of 7

Thread: SA 200 Murphy Temp and Pressure Gauge

  1. #1
    Join Date
    May 2018
    Posts
    45
    Post Thanks / Like

    SA 200 Murphy Temp and Pressure Gauge

    Just recently purchased a couple of Murphy gauges (Temp 20T-250 and Pressure 20P7-75) with a relay and socket and a little confused about hooking it all up. Be the first to say I am not a mechanic nor do I claim to be one but I like a challenge.

    I am trying to figure out how to wire up the relay to the gauges themselves and any help would be appreciated.

    If you plug the relay into the socket here is how the pins would correspond to the wire color.

    Pin 87A (Yellow 12 AWG)
    Pin 87 (White 12 AWG)
    Pin 86 (Green 14 AWG)
    Pin 85 (Black 12 AWG)
    Pin 30 (Red - 12 AWG)

    My understanding is Pin 30 runs to the Positive side of the ignition coil and Pin 85 goes the ground on the chassis but how do the other 3 pins connect and do you put in in-line fuse between the ignition coil and pin 30 in case something happens? Also, where do you run the hose for the oil pressure gauge?

    I had searched the forums on Murphy gauges and saw some installed but never saw an example of how to hook one up.
    Attached Images Attached Images  
    Last edited by pipewelder; 09-13-2021 at 04:49 PM.

  2. #2
    Join Date
    May 2018
    Posts
    45
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    Does this look possibly like it might be the correct setup for this configuration?

    Name:  20210913_185741(0).jpg
Views: 129
Size:  51.5 KB

  3. #3
    Join Date
    May 2014
    Location
    Central Wa. state
    Posts
    5,299
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    Nope, 85 and 86 are the terminals to trigger the relay coil. 30 and 87a will control your ignition coil circuit. So power to 85, and 86 goes to the gauges to trip the relay. Does the oil pressure gauge have an over ride button to start the engine until the needle rises? If not, you will need a normally closed spring loaded switch to over ride the oil pressure guage between the ignition power and terminal 85.
    I'll try to get time to scribble a diagram in a bit.

  4. #4
    Join Date
    May 2014
    Location
    Central Wa. state
    Posts
    5,299
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    I hope my crappy handwriting works for you.Name:  20210913_172847.jpg
Views: 124
Size:  68.8 KB

  5. #5
    Join Date
    May 2018
    Posts
    45
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    Thanks for the reply 12V71.

    I hope I have a grasp on this, so I will try and explain what I think I know about the diagram.

    By wiring the engine coil (positive side)to the 87A, that makes the circuit NC(normally closed) which passes current to pin 30(normal power pin on relays). The IGN(toggle switch) operating as the ON\OFF will keep current from passing on until the toggle switch is flipped to ON and the engine is started and once started the gauges will activate from what I see in the diagram. Pin 87 will never be needed because that is what makes the relay NO(normally opened). Correct me if I am wrong in the above statement. Just trying to get a handle on all this in case I ever have to troubleshoot the welder or bypass anything to get it started.

    My oil pressure gauge does not have a over-ride button, only a lockout button. Do you have any recommendations for the the Override Switch. I assume it will also need some hole drilled in the front panel to mount it and will need to be held in when hitting the Start button?
    Last edited by pipewelder; 09-14-2021 at 11:46 AM.

  6. #6
    Join Date
    May 2018
    Posts
    45
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    @12V71

    If you had a relay that only had 4 pins (minus the 87A) an hooked it up the same would it not need the override? If the ignition switch was not engaged, the circuit would be open and would not close until the ignition switch was flipped. Am I understanding this correctly?

  7. #7
    Join Date
    May 2014
    Location
    Central Wa. state
    Posts
    5,299
    Post Thanks / Like

    Re: SA 200 Murphy Temp and Pressure Gauge

    Quote Originally Posted by pipewelder View Post
    Thanks for the reply 12V71.

    I hope I have a grasp on this, so I will try and explain what I think I know about the diagram.

    By wiring the engine coil (positive side)to the 87A, that makes the circuit NC(normally closed) which passes current to pin 30(normal power pin on relays). The IGN(toggle switch) operating as the ON\OFF will keep current from passing on until the toggle switch is flipped to ON and the engine is started and once started the gauges will activate from what I see in the diagram. Pin 87 will never be needed because that is what makes the relay NO(normally opened). Correct me if I am wrong in the above statement. Just trying to get a handle on all this in case I ever have to troubleshoot the welder or bypass anything to get it started.

    My oil pressure gauge does not have a over-ride button, only a lockout button. Do you have any recommendations for the the Override Switch. I assume it will also need some hole drilled in the front panel to mount it and will need to be held in when hitting the Start button?
    The lockout button is also the over ride to start the engine. Press it and watch the needle lift off the contact.
    I don't have any other answer than supply ignition switch power to #30 and #86, #87a will go to the engine coil, and when the gauges ground #85 that opens the circuit to the coil and shuts the engine down. I've done quite a few of these setups on hay balers with small Cummins engines, using the relay to break the hold-in circuit on the fuel solenoid.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Page generated in 1,638,759,775.13833 seconds with 12 queries