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  1. #1
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    Hobart C44A Not Automatically Stopping

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    I'm having a brain fart troubleshooting this dishwasher. As the title of the thread says, the dishwasher is not shutting down automatically after the 4LS (C-NC) circuit opens. I suspect the 2TR Autotimer is defective, but I'm not 100% certain. Here's why:

    I check voltage at terminal #6 on the 2TR Autotimer during operation. When the tray enters the dishwasher, 4LS C-NC closes and I get 120V at terminal #6, switch 1-2 on the 2TR closes, which closes the 4CR contacts to energize the conveyor and pump motors. After the tray moves past the rack start switch, the switch opens, which should cause the timer to start counting down. I have it set to 60 seconds, but the dishwasher is not shutting down. What's got me stumped is I can pull the wires off terminal #6 and the timer will time out as it should even though there is no voltage on those wires. That's what has me stumped. For the record, the Auto/Manual switch is set to Auto (4S 2-3 and 5-6 are open).
    With your chrome heart shining in the sun, long may you run.

  2. #2
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    When you put a rack into the machine, 4LS switch close, sends power to terminal 6 on the 2TR autotimer and the timer resets. When 4LS switch opens up, you lose your 120v to terminal 6 and the timer starts to count down. If your timer is not counting down, check to make sure you are not getting 120v to terminal 6 all the time. if you do then the rack start switch is bad

  3. #3
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    Don't condemn the AUTO-TIMER yet. I'd scrutinize it more thoroughly with a voltmeter before saying for sure that the auto-timer is a fault.

    You said it works as it should when you remove the wire from 2TR #6 and times out properly. So, when you DON'T remove that wire...and a rack has already moved past the actuator so that Rack Start Switch 4LS supposedly opens, are you getting any voltage to terminal #6 THEN?

    If you're seeing ANY voltage to 2TR #6 when you shouldn't, that could be enough to continue a "gate" signal to the triac in 2TR.

    4LS is a reed switch under the panel below the prewash (or in your case, WASH) door. It's a rather low duty control, they do fail. Its contact may be sticking closed. OR...it may have gotten wet and thereby bridging the outside terminals. I think it has open terminals vice "molded" and sealed wires from it.

    4S is the AUTO/MANUAL rocker switch up there on the left side of the control box. I'm not there so I can't see the wiring. However, if the wire off of its terminal #2 also goes straight to 2TR #6, then you probably already eliminated 4S as the suspected cause.

    It may NOT be that way though. Again, I'm not there to see how it's wired, but there's a possibility that the output wires from 4S and 4LS run to a junction first at the terminal board before leading to 2TR #6. From my experiences, Hobart's schematics aren't perfect and may have left out that little detail. If you only have one wire leading to 2TR #6, then this may be the wiring setup. So depending on the wire routing, 4LS could also be suspect.

    Do that voltage check. If you see ANY voltage to 2TR #6 when you shouldn't be, take a better look at 4S or 4LS switches by isolating them from each other and doing more testing.


    OH....and by my having to think a little more than I'm accustomed to when I just woke up this morning, THANKS for your question!
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  4. #4
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    Quote Originally Posted by ECtofix View Post
    You said it works as it should when you remove the wire from 2TR #6 and times out properly. So, when you DON'T remove that wire...and a rack has already moved past the actuator so that Rack Start Switch 4LS supposedly opens, are you getting any voltage to terminal #6 THEN?
    Yes and no. When I pull the wires off terminal #6 I am getting ~60V to ground on terminal #6 of the time delay relay. However, there is no voltage whatsoever to the two wires coming from 4S-2 and 4LS-NC. I have a C64A dishwasher in another kitchen and it, too, has ~60V to ground when the wires are removed. That's what's driving me crazy. Both dishwashers test the same, but the C44A doesn't time out and the C64A does. Also, for some reason it's not showing on the wiring diagram, but there is a "plug-in module" on the time delay relay (see below) that has the dial to adjust the time from 0-180 seconds. I'm not certain, but I believe it plugs into terminals 4 & 5 of the time delay relay.

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    Quote Originally Posted by ECtofix View Post
    If you're seeing ANY voltage to 2TR #6 when you shouldn't, that could be enough to continue a "gate" signal to the triac in 2TR.
    Well, like I said, there is ~60V to ground, but I get the same voltage on the C64A dishwasher, which times out with no problems.

    Quote Originally Posted by ECtofix View Post
    4LS is a reed switch under the panel below the prewash (or in your case, WASH) door. It's a rather low duty control, they do fail. Its contact may be sticking closed. OR...it may have gotten wet and thereby bridging the outside terminals. I think it has open terminals vice "molded" and sealed wires from it.
    I have checked the switch many times using my meter and I have not found the contacts sticking closed. When the rack engages the switch mechanism, the contacts always close. And, when the rack disengages the switch mechanism, the contacts always open. That was the first thing I tested when the dishwasher started having shut-down issues. I've tested it numerous times and I even swapped it with the door switch.

    Quote Originally Posted by ECtofix View Post
    4S is the AUTO/MANUAL rocker switch up there on the left side of the control box. I'm not there so I can't see the wiring. However, if the wire off of its terminal #2 also goes straight to 2TR #6, then you probably already eliminated 4S as the suspected cause.
    Yes, I have checked and re-checked the AUTO/MANUAL rocker switch ad nauseum. When the rocker switch is set to AUTO, the contacts (2-3 and 4-6) are open.

    Quote Originally Posted by ECtofix View Post
    It may NOT be that way though. Again, I'm not there to see how it's wired, but there's a possibility that the output wires from 4S and 4LS run to a junction first at the terminal board before leading to 2TR #6. From my experiences, Hobart's schematics aren't perfect and may have left out that little detail. If you only have one wire leading to 2TR #6, then this may be the wiring setup. So depending on the wire routing, 4LS could also be suspect.
    I'm fairly certain the wiring diagram shows all the wiring correctly. There are two wires (red/white) on terminal #6.

    Quote Originally Posted by ECtofix View Post
    Do that voltage check. If you see ANY voltage to 2TR #6 when you shouldn't be, take a better look at 4S or 4LS switches by isolating them from each other and doing more testing.
    Been there, done that. I've probably logged 5 hours on this damn machine. It's driving me crazy.


    Quote Originally Posted by ECtofix View Post
    OH....and by my having to think a little more than I'm accustomed to when I just woke up this morning, THANKS for your question!
    I'm glad I could give your brain some exercise! I really appreciate your help.
    With your chrome heart shining in the sun, long may you run.

  5. #5
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    Well heck…

    OUR last remaining early model C-line A series machine like YOURS was just recently replaced with a Cle series machine. Otherwise, from my own curiosity I would’ve raised the hood on it to do the same testing as you did. We do have a model C-line in another dish room (our oldest machine), but it’s a later model than yours - with a fancied up clutch control board instead of that simpler timer module.

    I understand your frustration. You obviously know what you’re doing. I’ve gotten stuck doing the same “double & triple-checking” myself…many times…and will probably do it again…sooner rather than later. That’s the investment we strive to be thorough and accurate in our troubleshooting technique.

    I’d work with a guy like you ANY day before I’d ever want to get within ten feet of a parts-changer.

    ANYWAY…back to the topic:

    That 60v you’re getting might be feedback through the timer’s internal circuit. After all, terminal #1 stays hot at all times (except when safety & limit switches open).

    Your testing of two machines for comparison readings is a certainly a benefit and, based upon your tests, that auto-timer certainly seems to be the culprit. The only other suggestion I can make before getting the $100 replacement in there would be to swap the two timers between those two machines (of course, only if geography isn’t an issue) to see if the problem follows the timer module.

    By the time you read this though, I'm guessing you've probably done what's necessary to fix it...

    I’ll interject one more observation though. You said you made voltage tests while referencing to GROUND.

    I questioned this, so I looked at a full diagram that I have a copy of. Okay – YES, transformer 3T’s terminal X2 is bonded to ground. Therefore that makes ground and X2 common. So...there shouldn’t be any issues with referencing to ground. I’ve worked with many techs that do the same thing.

    However, as a rule, I've never fallen into that habit. I do OFTEN refer to ground, but generally as only an expedient way to see if a wire or component is HOT. Ultimately, I still go to the trouble of testing ACROSS the component I’m having troubles with.

    I’ve always said that, while troubleshooting an electrical component…”look at its electrical inputs the way that component sees it.” If you reference to ground, you’re bypassing the wiring (and connections) which provides for the OTHER SIDE of that component…and any problems that may lie therein.

    If you’re not already doing this the same way as I do, I’m merely suggesting that you (and anyone else reading this) are potentially overlooking problems that may exist that you’re not seeing.

    Therefore, make your final, conclusive voltage readings across terminals #6 and #3 instead of #6 and ground. It’s short and it’s quick and it’ll confirm that there aren’t any issues within the masses of that dish machine's gray wiring (COMMON) that delivers that timer its NEUTRAL input.
    ...Or...it may actually reveal an issue that ultimately proves to be the problem...thereby causing the solid-state components in that timer to go all cock-eyed in their performance.
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  6. #6
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    First, thank you for your gracious comments. I appreciate your pointing out my referencing to ground when checking voltage. I do know better and I will follow your excellent advice when I spend some time with the machine in the morning before the kitchen staff arrives. The machine and I usually get to spend 30 minutes together in the morning, but I'd prefer to end the relationship and spend that time doing something more productive.

    Today, I realized I forgot to mention I had swapped the two timers and, unfortunately, the results were the same.

    I'm not giving up. Even though the lady working the machine knows to manually shut it down, I know she would prefer it does it on its own.

    I'll post back when I finally figure it out. Again, thanks for your time and for sharing your expertise with me.
    With your chrome heart shining in the sun, long may you run.

  7. #7
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    Dumb question - does the unit have a delime switch behind it? If its in delime mode, it would stay running while the delimer does it job.

  8. #8
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    Quote Originally Posted by Kevin_1963 View Post
    Dumb question - does the unit have a delime switch behind it? If its in delime mode, it would stay running while the delimer does it job.
    No delime switch.

    I got to talk to a Hobart Houston dishwasher technician today. I gave him the blow-by-blow on everything. His diagnosis of the problem is the rack start switch. He claims even though I'm testing the switch as being open after the rack passes, it still could be the culprit. I'm not buying it because I had already swapped it with the door switch. But, just to cover all the bases, I'm going to remove the rack start switch from another dishwasher and see what happens.
    With your chrome heart shining in the sun, long may you run.

  9. #9
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    It turns out the Hobart guy was right. I didn't mention this in my last post, but he suggested before I swapped or replaced the rack start switch that I back off on the tightness of the nylock nuts holding the reed switch/PCB board to the all-thread rods. His reason was that if the nuts are tight, the heat radiating from the dishwasher will cause the PCB board to warp and affect the switch. I questioned him as to how this could be because I wasn't getting voltage to terminal #6 of the timer. He didn't know exactly why. It just did.

    So, I took his advice. It took a couple of adjustments, but the dishwasher is now timing out and shutting down. Crazy stuff.
    With your chrome heart shining in the sun, long may you run.

  10. #10
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    SS, a few questions:

    When you say "reed switch/PCB board", are you talking about the rack start switch?

    Is the rack start switch actually inside the machine (conveyor), or by the front loading table (activated by a armature when a rack is pushed in place)?

  11. #11
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    Quote Originally Posted by Kevin_1963 View Post
    SS, a few questions:

    When you say "reed switch/PCB board", are you talking about the rack start switch?

    Is the rack start switch actually inside the machine (conveyor), or by the front loading table (activated by a armature when a rack is pushed in place)?
    By "reed switch/PCB board", I'm talking about the actual switch. Hobart calls it a "reed encapsulated switch". The reed part of the switch is encapsulated inside a glass tube. The wires to each side of the switch come out of the glass tube on either side where they are soldered to the wiring terminals mounted onto a PCB board where the wires connect. The reed switch/PCB board is mounted on the outside of the machine to two all thread rods at the same height as the rack track. The mechanism that activates the switch is a magnet mounted on an actuator arm inside the dishwasher opposite the reed switch/PCB board. As the rack enters the dishwasher, it causes the actuator arm/magnet to move towards the switch which closes the contacts, which starts the timer. When the rack moves past the actuator arm/magnet, the arm/magnet swings away from the switch, opening the contacts, removing voltage from terminal #6 of the timer, which causes the timer to start counting down. After the timer counts down, the conveyor and pump stop.
    With your chrome heart shining in the sun, long may you run.

  12. #12
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    ...And, of course, the timers purpose is to allow sufficient operating time for that given dish rack to travel completely through the machine - then the timer times out and stops the pumps and conveyor operation. The timer gives the machine a break during slow usage when being fed just an occasional rack of dishes. Saves wear & tear on the machine, keeps the intrusive noise of the running machine to a minimum and conserves energy.

    Sandshark, thanks for posting what the outcome on this was. Definitely not something I would've considered. I'll remember it for future reference.
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