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  1. #1
    Join Date
    Jun 2010
    Posts
    5

    Hobart 135 Relay Issue

    I purchased a used Hobart 135 with what seems to be the very common sticking closed CR1 relay. The previous owner used it like this for two years!

    The machine hums, and receives electricity to the wire even with the on off switch in the OFF position. Further, the gas valve is always on, with this sticking relay. The fan turns on, and the wire feed works once I switch the on off switch to the ON position.

    After reading multiple posts, from others with the same problem, I took the cover off, blew out the insides with compressed air, and lightly tapped the two relays, CR and CR3 about ten times with a screwdriver. Thought I heard a click after that tapping.

    Plugged the machine in. and guess what, no humming, no hot wire. Turned the power switch to the ON position, and the welder functioned normally. Seems to be fixed for now.


    Questions.....
    What causes these relays to stick shut?
    Will this be an on-going problem?
    Should I just change out the relay anyway? Or is that not necessary now?

    Thanks for your input.

  2. #2
    Join Date
    Apr 2009
    Location
    land between the lakes tn
    Posts
    116
    being a cheap sob , my motto is if it ain't broke , don't fix it , i've got a late 135 and have never had any problems (yet)
    Silver Hair Deere
    Hobart Handler 135

  3. #3
    Join Date
    Jan 2010
    Posts
    34
    maybe just age, or the relays might have arced somewhat inside (doubting it)
    relays do have a limited lifespan, and they may be reaching it. replace them if they don't work at all, or they malfunction in a way that affects your welding in a negative way.
    Always assume every project you take on will take twice as long and cost three times as much as you estimate.

  4. #4
    Join Date
    Jun 2010
    Posts
    5
    Well, the CR1 relay appears to not be functioning correctly after all........so, having read some other posts on here from others with the same problem.........

    I bought a a Tyco relay part number T90S5d12-24 relay as a replacement for the oem Control Relay 1, part number NT90RHAS24CB. This is supposed to be the correct match from what others here have said and it`s what the electronic parts dealer supplied me with.



    The question that I have, is....
    The oem CR1, NT90RHAS24CB only has 5 pins coming through on the circut board, not 6, like the Tyco replacement T90S5D12-24 does. If held in the palm of the hand, with pins facing up, it`s the large pin on the top left that is absent. Is this pin needed for the relay to function correctly? I dunno if that pin was just clipped off-as in not needed, and then the relay installed? I have not removed the faulty CR1 yet to find out.

    IS this the correct replacement that matches the NT90RHAS24CB oem relay?


    The only other relay on the welder circut board, in the CR3 slot, is a NT90RHCS24CB, which the Tyco T90S5D12-24 being a direct fit with the orientation of the 6 pins.

    Here`s a PDF on the Tyco relay http://relays.tycoelectronics.com/da...ts/T90N_DS.pdf

    That top pin looks to be part of the contact points, as per the pics in the pdf file.


    Anybody changed this CR1 out yet?? Results??

    Thanks.

  5. #5
    Join Date
    Jun 2010
    Posts
    5
    So I founmd this web site to learn more about how relays work. http://www.bcae1.com/relays.htm

    I see that the Hobart 135 uses SPDT, or single pole double throw`relays. Now I see what that top pin is for, it`s one of the throw points for the contact, and the pin just below it is also for the contact. One of those pins will be contacted when energized, and the other pin will be contacted when de-energized.

    OK. Now I have a feel for the what happens inside of the rely. But, I still need to know if that top pin is needed and how it applies to the CR1.

  6. #6
    Join Date
    Jun 2010
    Posts
    5
    1731 views and just two replies??

    Hummmmmm. Surely someone has replaced this troublesome relay........

  7. #7
    Join Date
    Apr 2003
    Location
    Troy, Ohio
    Posts
    476
    Quote Originally Posted by Spokerider View Post
    So I founmd this web site to learn more about how relays work. http://www.bcae1.com/relays.htm

    I see that the Hobart 135 uses SPDT, or single pole double throw`relays. Now I see what that top pin is for, it`s one of the throw points for the contact, and the pin just below it is also for the contact. One of those pins will be contacted when energized, and the other pin will be contacted when de-energized.

    OK. Now I have a feel for the what happens inside of the rely. But, I still need to know if that top pin is needed and how it applies to the CR1.
    The relay CR1 has contacts that, when energized (closed), allow current to flow to the transformer primary winding. When relay contacts make and break an electrical circuit, sometimes they will flash (arc). Over time, this arcing could cause the relay contacts to stick or weld shut.

    On the CR1 relay, the contacts used are the normally-open contacts (N.O.). When the relay coil is energized, the contacts close and complete the electrical circuit.

    The relay that you're looking at that has both a normally-open contact and a normally-closed contact will work just fine as a replacement for CR1 as there is no circuit trace on the board that connects to the pin of the N.C. contact.

    Here's a SPST relay with the same board mount configuration that has a little higher current rating than the relay that you're looking at:

    http://search.digikey.com/scripts/Dk...&name=Z1008-ND

    Darrell

  8. #8
    Join Date
    Jun 2010
    Posts
    5
    Darrell,
    Thank you for addressing both of my questions, informing me of the correct replacement part for the CR1 and the fact that the top pin on the relay does not have to be soldered into the board.

    I will order the part and get this problem fixed

    Hopefully others experiencing the same problem with a CR1 relay will find this post of use.

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