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  • C44AW question

    Posted by nafets47 on July 26, 2022 at 4:26 pm

    So my Hobart DW has been acting totally fine up until today.

    The 3.2A fuse continues to fail in the control center of the machine. I replaced it first to see if the main contactor pulls in and to start trouble shooting but it blows after 1 second. I replaced it again to see which of the contacts is being problematic and I saw that the 5CR was flickering off and on and sparking which makes me believe it could be the issue. Per the manual from Hobart 5CR is the gas relay and deals with the ignitor board.

    Is there any idea on what to do to trouble shoot this. I dont really want to keep blowing $5.00 fuses. This is the first time I have run into an issue where I need to check what is causing a fuse to blow.

    I attached the manual to this post so whoever has some insight we can be on the same page.

    This is a scanned manual so searching through it is kinda old school. For reference the page that I am quoting about 5CR is page 52

    nafets47 replied 1 year, 8 months ago 2 Members · 2 Replies
  • 2 Replies
  • ectofix

    Member
    July 26, 2022 at 5:32 pm

    I’ll assume that your machine is 3 phase, 208 (or 480) and has a step-down transformer to 120v. The 120 is used to power all control devices (contactors, solenoid valves, gas heat controls, etc.). That 3.2a amp fuse is there to protect the transformer in the event of a short circuit somewhere in the 120v circuit.

    I take it the machine is already full of water…which would explain why 5CR is trying to energize so soon?

    From what I see in the schematics from that old manual, 5CR energizes after the left tank’s lower float switch (the 4 wire one) closes, then 5CR’s contacts close to power the left tank’s igniter board.

    Anyway, you obviously have a short somewhere in the 120v circuit. 5CR is an ice cube relay. It may be arcing simply due to its contacts being pitted. Arcing contacts won’t blow a fuse. However, I recommend you address that first by checking the circuit it energizes using an ohmmeter.

    From my own experiences, that fuse blows due to a shorted solenoid valve or contactor coil, a shorted float switch (rare), a shorted door switch…or a wire somewhere that has rubbed out to ground.

    The FIRST thing you should do is a VERY thorough visual inspection of all components and visible wiring. I’m sure you already know what you’re looking for.

    If you find nothing burnt, chafed, deformed, gotten wet, etc. – then you can proceed by going about this in two ways:

    1. Remove power from the machine, then use your ohmmeter to go through all the individual 120v circuits branches to find any unusually low resistance paths (or continuity). Do so using some logic by knowing what should get energized WHEN. So, what get energized just by turning the unit on, then what gets energized after certain processes have completed (e.g., tank must fill to a certain level before heating, etc.).

    2. Another way to troubleshoot for a short circuit is by doing what I call “trial by fuse”. YES, you should be equipped with numerous spare fuses. THEN, disconnect ALL components, power the unit up, then CAREFULLY, slowly and meticulously reconnect stuff ONE AT A TIME…until your sacrificial fuse blows. Obviously whatever you reconnected LAST will lead you to where the short is at.

  • nafets47

    Member
    July 27, 2022 at 2:54 pm

    Thank you very much for the guidence.

    Ended up being the blower motor going to ground. Took about 2 hours. But fingured it out. Happened to have a spare sitting around that I had pulled the shroud off earlier.

    Another point for ectofix.

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