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  • Rational SCCWE62G dead

     nafets47 updated 6 months, 1 week ago 8 Members · 107 Posts
  • nafets47

    Member
    January 13, 2020 at 1:26 pm

    Checked fuses F1 and F2 as well as thermal safeties, LWCO for boiler.

    Absolutely nothing is happening on the display, I hear relays clicking however screen is dead and cooling fan not turning on.

  • olivero

    Member
    January 13, 2020 at 2:17 pm
  • ectofix

    Member
    January 13, 2020 at 4:10 pm

    @Nafets47,

    Whereabouts are the  relays you say are clicking?  Is the main contactor pulling in?

    Are you in the U.S?  Could you please provide a serial number of your oven?

  • ectofix

    Member
    January 13, 2020 at 4:26 pm

    I’ll just proceed with some possibilities by assuming you have a version E or G oven and are located in the U.S.:

    • If the main contactor K1 is NOT pulling in, then check F7.  It’s an in-line fuse located in the wiring from the round “special” transformer.
    • If the main contactor IS pulling in, then I suggest unplugging the bus cable connections (the telephone jack-looking ones) for inspection.  If there’s corrosion, the that’s probably your problem.
  • nafets47

    Member
    January 13, 2020 at 5:30 pm

    The model is a G. And I am based in the US.

    The main contactor is pulling in and I checked the special transformer fuses and those are not blown.

    From what I could tell it appears that the PCB has failed.

    • ectofix

      Member
      January 13, 2020 at 5:36 pm

      If the main contactor is pulling in, then it’s possible that the main contactor’s contacts are bad.

      Do you have a schematic?

    • ectofix

      Member
      January 13, 2020 at 5:39 pm

      I still suggest taking a good look at the RJ45 bus connections.

  • olivero

    Member
    January 13, 2020 at 8:35 pm

    I worked with him on this to try and figure out what happened.

    The cooling fan doesen’t run but it’s possible it’s still good.

    I also measured power at the main contactor and it’s good, 120V on both legs which is what I’m assuming is correct.

    There’s LED lights that come on, one on the board mounted on the oven, can’t tell on the screen board itself. When you turn it on you can hear things clicking, not sure what’s clicking.

    • ectofix

      Member
      January 14, 2020 at 5:33 am

      I think you’ll find three poles of the contactor in use.  TWO poles are the 120v in, which supplies power to the main blower motor.

      The THIRD pole of the contactor is 230v from the special transformer, serving as the latching circuit to keep the contactor energized…and to power everything else. 

      How about fuse F5 on the control transformer?

      And…I hate to sound like a broken record, but – how do the BUS cable connections look?

  • beef

    Member
    January 14, 2020 at 7:08 am

    Push all the buttons twice, if nothing happens then replace it….. ?

  • olivero

    Member
    January 14, 2020 at 11:49 am

    The 120V is present at the contactor, coil is energized.

    Didn’t see an F5 on the control transformer but I’m assuming it works since the 120V is present.

    Would it at this point be the control PCB?

  • fixbear

    Member
    January 14, 2020 at 12:28 pm

    Is the relay latching in?  and reread Ectofix’s post:

    The THIRD pole of the contactor is 230v from the special transformer, serving as the latching circuit to keep the contactor energized…and to power everything else.

    How about fuse F5 on the control transformer?

    • fixbear

      Member
      January 14, 2020 at 12:38 pm

      control transformer

      See the fuse?

      • olivero

        Member
        January 14, 2020 at 12:41 pm

        It’s inline? I think I see it.

        There is 230V present at the 3rd connection on the contactor, I measured it, it’s there. 

        There’s 120V on the first 2 and then 220-230V on the third one. The K1 is pulling in.

        Don’t know about the fuse

      • fixbear

        Member
        January 14, 2020 at 12:51 pm

        Or this one depending.

      • ectofix

        Member
        January 14, 2020 at 4:35 pm

        Here’s the control transformer: 

        40.00.277

        Input is 230v and is a multi-tap secondary for 2.5v, 11.5v and 12v.

        If the 2.5v isn’t present at the operator PCB, then it won’t light up (dead).

        @fixbear, the one you linked is the “special” transformer. 

        Since the oven is made in Germany, they use 230v components throughout.  That torroidal transformer added in there allows the 230v oven to work from 120v here in the U.S.

        Amazingly enough, ALL through a .8a in-line fuse.

        • olivero

          Member
          January 14, 2020 at 4:38 pm

          Okay, so if you have the 120V present, then the control transformer is working?

          • ectofix

            Member
            January 14, 2020 at 5:16 pm

            No.  Two totally separate circuits.

            The only components that see 120v are:

            • the special (torroidal) transformer – directly from the power cord
            • the main blower motor – through two poles of K1 contactor.

            That’s the extent of the 120v usage. 

            Everything else receives 230v from the torriodal transformer, primarily via K1’s third set of contacts:

            • the cooling fan
            • the gas train components
            • the solenoid valves
            • the three water pumps.

            The control transformer also receives 230v.  It’s secondary output supplies:

            • the operator board
            • the I/O board
            • various control circuitry at an electronics level of input…
            • and things like the cabinet lights and buzzer.

            • olivero

              Member
              January 14, 2020 at 5:19 pm

              Okay, so if I saw 120V at the contactor on the first 2 terminals, K1 and it was engaged, why wouldn’t the cooling fan be on?

              I saw 220-230V at the last terminal on K1.

              • ectofix

                Member
                January 14, 2020 at 5:36 pm

                Ya got me there, so I had to look.  I made a mistake.  First one this year.  My apologies for the misleading information about that.

                The cooling fan is 230v too.

                K1 first two sets of contacts routes the 120v to the main blower motor.

                Sheesh!  I rushed through six pages of the schematic on my computer screen and got a little little twisted, I guess.  I MUCH prefer hard-copies.

                I’ll go back and revise my posts.

                • fixbear

                  Member
                  January 14, 2020 at 6:50 pm

                  I MUCH prefer hard-copies.

                  Your not alone on that one.  Wait till your eyes get older.

                  • fixbear

                    Member
                    January 14, 2020 at 7:35 pm

                    It’s sad that they don’t make the schematics like Hiedelburg, Miller, Man/Roland or Polar. The “books” are about 4 to 5 hundred pages long, but due to the complexity of the machines are easy to read once you understand their system. Two to three electrical Cabinets, One on the feeder and one on the delivery and sometimes one Mid. Often with over a hundred contactors and relays.  But the system was easy to understand.

              • ectofix

                Member
                January 14, 2020 at 6:00 pm

                Also forgive my delay about why the cooling fan might not be working.  I’m juggling thoughts on this while trying to get dinner in the oven.

                The THIRD set of K1 contacts supplies 230v to the cooling fan and an input to the I/O board.

                Maybe the fan is bad or maybe there’s a bad connection somewhere.

                • olivero

                  Member
                  January 14, 2020 at 8:26 pm

                  Okay, well that makes it a bit more confusing.

                  There was 230V at the contactor on the third leg, 120V on the first 2, if that cooling fan is powered at 220-230V, then why wouldn’t it work?

                  The thing we’re trying to solve is the main screen not coming on and nothing’s happening, now a $1300 board got overnighted so hopefully it’s the right one. 

                  I was just trying to verify that it WAS the part to replace before buying it.

        • fixbear

          Member
          January 14, 2020 at 6:41 pm

          I link’d both so he realized what he was seeing.

          • ectofix

            Member
            January 14, 2020 at 7:39 pm

            I thought you said “LICKED”.

            I couldn’t picture that.  Thanks for the correction. 

            LOL!

  • nafets47

    Member
    January 14, 2020 at 3:13 pm

    Thanks for the response to my question. I checked the connections and the looks good, no damage or build up and like Olivero was saying it is pulling the correct voltage.

    Each fuse that is on the diagram provided by Rational is good. After going through some data tree I found on their site it looked like the PCB was bad so I ended up ordering the PCB.

    Hopefully that fixes the issue.

  • nafets47

    Member
    January 16, 2020 at 10:55 am

    So the PCB was replaced and that was a bust. If the unit has power coming in, the fuses are functioning the contactor “pulls in” and provides power but yet the fan does not turn on – would that be the contactor?

  • nafets47

    Member
    January 16, 2020 at 1:18 pm

    Just got off the phone with Rational “tech support” very adamant that a local service provider should handle it.

    He did tell me however there are a total of 5 fuses on the machine, checked all 5 and they are good per a multimeter.

    Voltage on the transformers is good per the data provided by etcofix and fixbear.

    What else could be the issue? like I said earlier the fan is not turning on so it would appear that there is an issue earlier but the voltage is all reading correct.

  • fixbear

    Member
    January 16, 2020 at 2:09 pm

    Nafets47,  I thought this is what you would find.   I am not a Rational tech, and therefor don’t have drawings for your individual model.  But I did manage to find the training drawings that come close for your input voltage.  They are not as accurate as the ones on the machine  Also I don’t know how you measured the contactor output voltages nor do I know your line voltage.  The information I provide below is for single phase.

    On the special transformer output there is a fuse (F7). Your incoming power has to go through that to the cooling fan. as well as the control transformer.This transformer has multiple taps on the  input for your line voltage from 100V to 240V to make your required 230 that the machine is designed for. So you need to measure if you have the 230V output from that transformer. The K1 relay 13 and 14 supply the fan from the special transformer. and the control transformer also gets it’s power from the same, but not through that pole of the relay.

    Now the blower fan is direct off K1 pole 1   and pole 2   On the back of the motor are 2 fuses, F20 and F21

    There are several methods of using a voltmeter to test the relay contacts. The fastest in this application is to just measure across the pole your checking powered for 0 volts. anything other than 0 the pole is open.  This is how we determine what pole is open or has resistance. A relay that has a high resistance contact from arcing or wear will often show 5 to 10 volts under load.

    • olivero

      Member
      January 16, 2020 at 4:18 pm

      Fixbear, 

      When I measured it with him, we were getting on K1, the contactor, 120V on the 1st and 2nd leg, measured top and bottom to ground and top to bottom read 0V so it’s good. Then the 3rd pole is empty, the 4th has another set of wires which was reading 220V to ground.

      Nafets says he checked the fuses, so what would the next thing be to check? The transformers? It seems the 120V and 220V are both present, so what has to actuate to get power to the cooling fan to go?

    • ectofix

      Member
      January 16, 2020 at 4:26 pm

      Olivero,

      Using ground as a reference for the second side of a circuit is NEVER proper troubleshooting.

      In this oven, ground is NOT part of the 120v circuit at ALL.  AND…although half of the 230v circuit IS bonded to ground, you’re completely skipping over that second side by using ground as a test point.

      All wiring and connections for BOTH sides of the circuit are equally important.

      Make your voltage readings how the component(s) receives it.  Make both sides of your voltage readings AT THE COMPONENT that’s supposed to received it.

      • olivero

        Member
        January 16, 2020 at 4:57 pm

        Ectofix,

        Okay cool, I got you. 

        There is 220V on the inlet of A2 board, the brown and blue wire, across the 2 is 220V.

        So there is power to the CPU board but it’s not giving power to the cooling fan.

  • olivero

    Member
    January 16, 2020 at 4:22 pm

    Correction,  the model is SCCWE62G

    https://www.partstown.com/modelManual/RATL-SCCWE-62G_pm.pdf

    Page 60 or so, the wiring diagram begins.

    • ectofix

      Member
      January 16, 2020 at 4:29 pm

      So you’re saying this is a version H oven instead of a version G? 

      If you don’t understand where I’ve getting that distinction,  the oven’s version is the FIFTH digit in the serial number.

      • olivero

        Member
        January 16, 2020 at 4:40 pm

        Whatever I wrote above is what it’s saying on the label.

        I don’t know how they configure it. 

    • ectofix

      Member
      January 16, 2020 at 4:39 pm

      BTW:  I’m glad you found a schematic.  I was going to email one (albeit, for the wrong oven…we now know) to your friend, so I requested we CONNECT here in this forum platform.  That way we could trade emails.  He never responded.

      I asked if he HAD a schematic.  He never responded.

      I asked several OTHER relevant questions to which he never responded.

      I don’t mind helping another tech, but communication is a two way street.  Up to now I just about threw my arms up and walked away.

      • olivero

        Member
        January 16, 2020 at 4:44 pm

        Yeah, no worries. It can be a bit tricky, I’ve been on a lot of Forums for help so I understand, give him some time to get used to it, I’m sure we can make it work 🙂

  • nafets47

    Member
    January 16, 2020 at 4:36 pm
    • ectofix

      Member
      January 16, 2020 at 5:12 pm

      So now that we know we’ve been talking about the wrong oven all this time, let’s take another look.

      Now we’re talking about a White Efficiency (WE) oven.  A version H.

      The cooling fan in that oven is NOT powered by the special transformer’s output as it was in the version G oven.  Instead, it is powered through your control board, to a DC converter.  The fan is designed to run from a variable range of 18 to 28vdc.  Therefore, let’s stop worrying about the fan anymore.  The fan isn’t working because the board isn’t.

      Make an input voltage reading at your control board.  Plug X14.  That’s power in supplied from the control transformer.  You should read 18vac between pins 1 and 2, then 11.5vac between pins 3 and 4.

      DON’T use GROUND in your voltage readings.

      • olivero

        Member
        January 16, 2020 at 5:27 pm

        Okay, so he’s got 1-2 is 18.5V and 3-4 is 16.5V

        • ectofix

          Member
          January 16, 2020 at 5:43 pm

          There was an SD card in the old board…assuming the board he replaced was this one:

          Rational 42.00.080P CONTROL PCB

          Did he transfer the SD card to the new board?

        • ectofix

          Member
          January 16, 2020 at 5:56 pm

          @olivero,

          I’ve sent you a connection request.  Approve it and we can swap email addresses so I can send you something.

          • olivero

            Member
            January 16, 2020 at 8:41 pm

            I accepted you.

            I think he put the old board back in since the new one didn’t fix it.

      • fixitnow

        Member
        January 18, 2020 at 4:06 pm

        also the cooling fan in a WE unit only runs if the unit

         is in a cooking mode or if the temperature in the cabinet reaches a certain point. just turning the oven on wont neccessarily make the fan run

        • olivero

          Member
          January 18, 2020 at 7:28 pm

          Good to know, on Convotherm’s the cooling fans in the electrical compartment run regardless, as soon as the unit gets power, those fans run.

          That’s what I based it off of, so good to know I was wrong on that.

  • nafets47

    Member
    January 17, 2020 at 10:30 am

    @etcofix

    The PCB I replaced was not the 42.00.080P but the 42.00.112P so no SD card was removed.

    However looking over the Training Manual it goes over the point on pg 21 that LEDs above and below the SD card should be on, and that if the LED above the SD card is not on this PCB has failed and if the one below the SD card is off there is an issue with the power supply.

    However I found both to be not on, with the unit powered and the switch turned on.

    So it would appear that the power supply is the issue. I am going to test this a bit later today.

  • nafets47

    Member
    January 17, 2020 at 11:16 am

    So I checked the transformer and it is only providing 7 volts AC to the board when the manual says it should be providing 18V, additionally the transformer states on its casing it should provide 11.5-18V

    The correct voltage is coming into the the transformer 240V, so it would appear this is the reason for my issues.

    Does that seem accurate?

    • ectofix

      Member
      January 17, 2020 at 2:30 pm

      Sounds like a problem.  However, could you please tell me EXACTLY where you’re connecting your two voltmeter test leads so I can see it on the schematic?

      Remember that the control transformer has TWO secondary outputs.  So, explain your testpoints when you read BOTH voltages.

  • nafets47

    Member
    January 17, 2020 at 4:39 pm

    See attached picture

    • ectofix

      Member
      January 17, 2020 at 5:26 pm

      I don’t understand what test points you used in your picture.

      Did you do it like how I’ve illustrated in MY attached picture?

  • nafets47

    Member
    January 17, 2020 at 4:49 pm

    See attached picture

    The connector running off the port that I circled goes to X14 and I put my leads into that connector to test the voltage and when I leave just one lead in the connector and touch ground I get 7V and when I put one lead across 3 of the 4 wire terminals and the other across the last terminal I get 4V

    And when I tested 240, I put a lead on the terminal I “Xed” and the other on ground and got 240

    • ectofix

      Member
      January 17, 2020 at 5:30 pm

      DO…NOT…USE…GROUND!

      Ground is NOT a proper test point.

    • ectofix

      Member
      January 17, 2020 at 5:31 pm

      Connect your test leads like I showed in my photo.

    • ectofix

      Member
      January 17, 2020 at 5:47 pm

      I’ll point out that you read 240v referencing ground because the special transformer’s secondary is bonded to ground for safety reasons.  However, there’s allotta wires and connections between that ground and that side of the 240v going to each component.  By using ground as a test point, you’re essentially COMPLETELY overlooking all those wires and connections in your troubleshooting. What if there was a faulty connection in that leg….and you don’t find it because you overlooked it…by assuming that it’s all the SAME?

      As for the CONTROL transformer’s outputs, there’s NOTHING on the schematic indicating that ITS secondaries are bonded to ground.  So, ground IS NOT part of the circuit!

      Actually, GROUND is NOT part of ANY circuit in this oven other than the ignition electrodes…which is another topic.

      I’ve alluded to this already in this same thread.

      To use a voltmeter as a troubleshooting tool, you MUST look at the supply voltage the same way the component receives it.  The voltmeter is your EYES looking in to see what the component is seeing…and getting as an input.

      GROUND is not a part of ANY of that.

      • fixbear

        Member
        January 17, 2020 at 6:13 pm

        Didn’t we rant and rave about using ground about a year ago. on a cooler?

        • ectofix

          Member
          January 17, 2020 at 7:06 pm

          More times than that, I think.

          It’s a learning curve, I guess, to listen to those of US who’ve been “troubleshooters” of equipment for DECADES. 

          Maybe using ground stems from old habits used for troubleshooting DC circuits in automobiles.

          Yet, I’ve found that even some electricians will do it. 

          I just shake my head and TRY to explain why you should NOT do it.

          I don’t know why it’s so hard for people to understand that GROUND r-a-r-e-l-y plays a part in a circuit.  On those rare occasions, then:

          • They STILL must scrutinize all…ALL wiring/connections between the power source and the component.
          • They must troubleshoot BOTH sides to the component. 
          • They must LEARN the ENTIRE circuit as they go to look for any possible or plausible potential problems.

          All of that is logical to ME (and YOU), but it takes some time and experience of learning that logic to TRULY and effectively troubleshoot electricity.  Some folks “get it” quickly.  Others (like myself) require MUCH more to finally get it.

          In MY case, I had to actually be assigned as an instructor in order to force me to REALLY school up on the trade.  Those four years in that job was a major turning point….and has served me well in these subsequent 35+ years back at it in the field of troubleshooting stuff.

          One thing’s for certain.  Attempting to “mentor” someone at the task of troubleshooting electricity… through pounding away at a computer keyboard as my only way to convey the logic….is EXTREMELY frustrating when compared to my actually being there in person to oversee its execution. 

          FWIW: I think I’ve gone “above and beyond” in THIS particular thread. 

          • olivero

            Member
            January 17, 2020 at 9:43 pm

            Definetley a learning curve, some of us were taught to measure to ground but what you are saying makes sense.

            Nafets and I are both not nearly as advanced as you guys are, no doubt about it and I definetley appreciate the time you are taking to help us figure it out.

            I plan on going over there tomorrow and taking another look know that I have a better idea of what I’m looking for. 

            When he checked pin 1-2 and 3-4 on the connector, the voltage was lower than it should be, 1-2 was 18.5V and 3-4 was 16.5V between the pins, not reading to ground.

            It seems that board is not getting the power it needs and as a result, no LED’s are lit on that board.

  • nafets47

    Member
    January 17, 2020 at 10:16 pm

    ectofix, got it on the not using ground.

    Like olivero was stating, was the way we were taught.

    Regardless, I went back and tested it again like you pointed out in your drawing and I was getting 240 where I was supposed to get 240, but was not getting 18v where I was supposed to get 18V.

    I am going to double check in the morning and try another volt meter to ensure that mine is not being finicky.

    One thing I wanted to know kinda separate to this, is the transformer has two fuses mounted to the device. Neither of these were bad/blown, is that peculiar that the voltage would not be correct coming out of it with the fuses still intact?

    The main reason I am asking is because that device was the second thing I checked (its fuses) and because they were good I skipped it and went on down the line looking for other things wrong. In your experience is this common?

    • fixbear

      Member
      January 18, 2020 at 8:31 am

      There are occasions that transformers get a open or short internally. This will throw them out of spec. Or total failure.  They are also built different ways. Simple ones will just multiply the input by the ratio for a output.  But they can be built to regulate so the a input will create a more constant output.

      One thing I learned about most German and Swiss machines over the years is that they have taps on the power transformers to compensate for distribution variations. Most European machines want to see 230v. I don’t have drawings or installation manuals for your particular machine, but if it has a over-voltage to the control transformer, you’ll have a high output  And increased voltages can damage components.  Small differences take a long time to cause a problem, but larger ones show up quicker.  I know in my state the power company public service rules allows them to provide as little as 194 volts to 250 on a 230V service.  That’s a big range, so we also always measure the service power at a install.  I’ve actually seen a power company’s regulator send a high enough voltage to a service panel that it arced through the back of the panel and started a house on fire. Service was only a few weeks old.  The power regulator on the pole is a floating core transformer. The output low voltage it designed to pull the core to a proper voltage. If it hangs, you have problems. I always liked to leave my Fluke 87 on record for a bit to see whats happening.

    • ectofix

      Member
      January 18, 2020 at 11:32 am

      Fixbear covered that better than I could’ve.

      * * * * * *

      Let me relate my OWN troubleshooting story from this past week:

      A steam table wasn’t heating. A two-pan well using a 120v, 3000w Chromalox element like in my attached picture.

      For troubleshooting this problem, I was limited in what I could do since the staff were serving food right above me. I needed to reach a resolution quickly.

      I knew the thermostat was energizing its two-pole contactor since I could hear it pulling in within the control box enclosure. Flex, liquid-tight conduit led the line and neutral wires from it to the element’s box. The element connections inside that box were horrible to access. An initial test with my voltage detector stick made it chirp and light up – indicating there was some semblance of line voltage in there.

      I managed to get me (with a flashlight in my mouth) and a voltmeter under there to get some readings from the element’s threaded terminal lugs. I got 0v.

      So, the question at this point was “What am I loosing…and where at?”

      Well, I don’t just guess at such things. I therefore took a minute at being a bit more methodical with my test leads. I reoriented my test points a few times.

      I took readings from the TWO incoming wire’s strands:

      120v.

      I took readings at the BOTH wire’s crimped terminals:

      120v.

      So far, so good…

      From there, I alternately moved ONE test lead off the wire terminal and onto its respective element threaded stud it was connected to.

      Through that brief dance with my test leads, I found I had the lost neutral connection between its wire terminal and the very threaded stud that it was plainly & securely connected to!  I was dropping all 120v at an invisible, bad NEUTRAL connection DIRECTLY AT THE ELEMENT…simply due to a MICRO-thin layer of oxidation that had formed between the wire terminal where it sat FLAT against the landing of the element’s terminal.

      That’s all it was! I subsequently took BOTH connections apart (line side too), cleaned them up with a brass brush and securely reconnected them. THAT got it going again.

      Easy peasy lemon squeezy!

      SO, how is this overly simple story relevant to this thread?

      WELL…WHAT IF… I’d used GROUND as a test point in this situation?

      I would’ve been seeing 120v to the element ALL DAY LONG…and been scratching my head over what the heck was going on here and possibly would’ve concluded that the element was bad.

      • olivero

        Member
        January 18, 2020 at 2:34 pm

        That is a very good point.

  • ectofix

    Member
    January 18, 2020 at 5:22 pm

    So, I’m curious of the outcome of this. 

    It’s Saturday.  Did you go back and look at this today?

    • fixbear

      Member
      January 18, 2020 at 7:02 pm

      Your not alone on this.  Funny how we get invested in a problem.

    • olivero

      Member
      January 18, 2020 at 7:29 pm

      No, I did not but it’s possible Nafets did.

  • fixbear

    Member
    January 18, 2020 at 6:58 pm

    If you don’t have any output on the gray pair and the white pair, ohm the primary winding (your 240 in)  If you have lost or have a low voltage on the secondary  (which the drawing shows as independent winding’s)  Check for it at the fuse and output terminal. F1 is the gray pair and F2 is the white pair. The center two terminals are the unfused ones, The control board (A2) also has a single 8 amp fuse on both supply’s. (Gray and White are linked on the board). That  may be your problem if it isn’t the transformer

  • olivero

    Member
    January 20, 2020 at 9:44 am

    So Nafets is out of the office for a couple of days, feeling under the weather so to speak.

    I could go over there and take a look at it, what is it you guys want me to look at?

    I haven’t spent as much time in this thing as Nafets so I’m not sure exactly where everything is but I’m willing to give it a shot.

  • techtownmayor

    Administrator
    January 20, 2020 at 12:15 pm

    This has been an incredible thread to follow. I’m so impressed at the skill level here, but even more impressed with the generosity of others with their time and knowledge. 

    This thread is a perfect example of what techtown is for – my hats off to all of you!

    • olivero

      Member
      January 20, 2020 at 12:26 pm

      I’m just happy it’s here or we’d be so utterly lost, lol.

  • nojail

    Member
    January 21, 2020 at 8:11 am

    I read through some of the posts and I think you all just need to go back to the beginning and basics.  Check safety circuit from troubleshooter.  Then go from there.  https://www.heritageparts.com/medias/RAG0168.pdf?context=bWFzdGVyfHBkZi1tYW51YWxzfDM1MTM5MjJ8YXBwbGljYXRpb24vcGRmfHBkZi1tYW51YWxzL2g1YS9oMGUvODk4MTcyNTYxMDAxNC5wZGZ8MDc0ZWYzNGM4YTBjZmM5OWMzNzA3MjIzNzY5ZTI0ZjQ0N2MyZDUyMjAxZTk4Y2RlYWRjMTM3MjkxYWUwNmMwZA

    • olivero

      Member
      January 21, 2020 at 8:40 am

      It’s very possible, we’re still learning how to SOP is on this unit and where everything is so I think you’r right.

    • fixbear

      Member
      January 21, 2020 at 1:33 pm

      I agree with NoJali on this.  Go to page 167 and down the check list.  I don’t think you ever checked the fuse on the special transformer.

  • nafets47

    Member
    January 21, 2020 at 1:11 pm

    I came back into the office for a couple hours today and went to check on this Rational.

    So I double checked the voltage on my transformer:

    When I check the two greys I get 5 volts, if I check the bottom two whites I get 9 volts.

    When I check the grey and white that are closest I get 18v, and when I check the grey and white farthest from each other I get 0v

    Then when I check the connector end before it connects to the PCB I get 14v.

    I was checking ohms and I got 13.8 when checking the 240V connection but got nothing on any of the grey and white connections with any alteration of sequence.

    Separately, thank you for answering my question about the transformer that was great data.

    And also thanks for explaining with a real life scenario how checking ground could leave you clueless.

    • fixbear

      Member
      January 21, 2020 at 1:38 pm

      so either a fuse is open or the winding is. on the secondary.  Meter is in AC volts mode, right.

      • nafets47

        Member
        January 21, 2020 at 1:43 pm

        Correct AC volts

  • nafets47

    Member
    January 21, 2020 at 1:42 pm

    So with the data to hand that when I check the voltage on both greys and both whites and it adds up to 14V and when I check the cable before it goes into the PCB and it reads 14V not 18V and per the data tree from the manual stating it should be 18V.

    Is it safe to say the transformer is the issue?

    The only reason I am hesitating on this as the issue is because of the point that when I checked the grey and white closest together I get 18V

    • ectofix

      Member
      January 21, 2020 at 4:31 pm

      Nafets47 replied:

      So with the data to hand that when I check the voltage on both greys and both whites and it adds up to 14V and when I check the cable before it goes into the PCB and it reads 14V not 18V and per the data tree from the manual stating it should be 18V.

      Is it safe to say the transformer is the issue?

      The only reason I am hesitating on this as the issue is because of the point that when I checked the grey and white closest together I get 18V

      You’re not understanding the transformer’s configuration.  That transformer has two separate and distinct secondary outputs because there are two separate secondary windings (look at the schematic).  The two gray wires supply output from one winding to the PCB and the two white wires supply the OTHER winding’s output ALSO to the PCB.

      • You DO NOT add them up.
      • You DO NOT need to read from one secondary winding to the other.
      • They are two SEPARATE secondary windings in that transformer.  They have NOTHING electrically in common with each other except for they’re each creating their own, separate induced voltages from a common magnetic field off the SAME PRIMARY WINDING.

      You said you only read 5 volts from one winding’s output (via the two gray wires) and and 9 volts from the other (via the two white wires).

      THAT’S the problem.  They should be reading 11.5 volts and 18 volt, respectively, but they’re NOT.

      If I was there, I’d be tempted to isolate the transformer (disconnect the PCB) to see what the transformer’s output would  be under those conditions.

      Then again, if there was something wrong with the PCB that’d pull the transformer’s output down so dramatically, then the fuses should blow.

      Sitting here studying your readings on my computer screen, I’d say you have a bad control transformer.  Possibly a shorted primary winding, but only to a point that it’s not overloading the 240 volt circuit enough to blow the .8a in-line fuse between it and the big toroidal (excuse me…SPECIAL) transformer.

      What I’m saying is that not ALL of the control transformer’s turns of the PRIMARY winding are in the game anymore because, somewhere in it, two of the MANY turns of that primary winding haveshorted together for some reason.  As such, the transformer is no longer creating a strong enough magnetic field to induce the specified output voltages.

      I don’t ever recall seeing a transformer do that, but it seems plausible…so, THAT’S MY theory.

    • ectofix

      Member
      January 21, 2020 at 4:53 pm

      Watch this video about transformers:

      Transformers 101: How They Work & How To Wire Them

  • nojail

    Member
    January 21, 2020 at 2:48 pm

    I linked wrong manual haha, but in any case need to just go down the list and re-affirm that the components check out good.  Don’t assume anything is good.

  • fixbear

    Member
    January 21, 2020 at 7:11 pm

    This control transformer has multiple taps on the input / primary side.  To make a multiple tap primary one has to solder each tap onto the winding as it is wound at specific number of winds. Also in a certain area for the taps to come out.  It’s not a easy thing to scrape off the varnish, flux, and solder on a wire.  Re varnish the joint. Continue to the next one and do it again.  All without nicking the winding wire.  The taps are usually on the same side where the armature isn’t.  With heat expansion and contraction you can bet there will be some joint rubbing of the taps.  Two taps on top of each other like the 110 and 240 that shorted would definitely do this.  13.8 ohms on the primary seems near normal, but I don’t have any way to verify that.  Somebody have one they can check? 

    • ectofix

      Member
      January 22, 2020 at 4:29 pm

      fixbear replied:

      13.8 ohms on the primary seems near normal, but I don’t have any way to verify that. Somebody have one they can check?

      Well, you made me look.  We had one in stock, so checked the windings’ resistances with my Fluke.

      13.3Ω between the 0v & 240v terminals:

      • olivero

        Member
        January 22, 2020 at 4:36 pm

        I’m gonna ask him to check this, pretty funny you had one on hand.

  • fixbear

    Member
    January 21, 2020 at 7:24 pm

    How can we have any certainty the the primary coil has a tap short. Simple, our Ohm meter.  Making sue you have quality leads that are sharp, measure the taps starting at the lowest and working up to the highest. If you have a tap rated at 100V and the next one is 120V, your Ohm valve should increase 20%. If the base tap is 120V and you have a 240, The value will double..

    • nafets47

      Member
      January 23, 2020 at 1:08 pm

      So I got the transformer in from PartsTown and replaced it. I checked the voltage on the grey wires and the white wires and they are 12V and 19V which is completely different than the transformer that I had replaced.

      Now the PCB has a light on the bottom of the card, however per the “trouble shooting tree” I attached if the light above the card is not lit that means the PCB is bad.

      Well I guess that was good to know the transformer was bad, unfortunate the PCB is also not working.

      Any idea why the transformer would “kick it” and also take the PCB with it? I mean its only 18V of electricity and none of the fuses were bad on the machine.

      Just seems odd, however the board could just be that sensitive.

  • fixbear

    Member
    January 23, 2020 at 1:59 pm

    Which board do you have in the machine, the original or the replacement you bought?

  • nafets47

    Member
    January 23, 2020 at 5:44 pm

    Original. The replacement one was not the PCB that I needed.

    The SCCWE62G has three PCBs, two of which are in the front panel and the other in the cabinet which is “main” PCB (has the SD card).

    Of course I bought one for the front panel because that is the only one on PartsTown that said “PCB” for this exact model, but I found that I needed:

    https://www.partstown.com/rational/ratl42-00-260p

    Which is the newest model, the original design has been made obsolete twice. And the original model when you try to find it on PartsTown or anywhere really is not available except on HeritageParts which states its obsolete then tells you again the next version is and finally TA-DA here we are with the newest version.

    I really do not like Rational right now.

    • ectofix

      Member
      January 23, 2020 at 6:14 pm

      Yes.  I totally agree…

      Rational changes their part numbers more than ANY manufacturer I’ve ever seen.

      I have twenty-eight Rationals to maintain.  1995 models and up to present. 

      I have thirteen different parts manuals to cover them all…and ALL the parts price lists they have published that I could find on the internet. 

      Those parts price lists are updated almost annually…and must be used to cross-reference for any parts number changes.

      SO.  Whenever I look up a Rational part in a parts manual, I immediately (before getting up to walk to our parts shelves) must look that part number up AGAIN…in their price list…to see if the part number had changed.

      All this makes maintaining the parts locations on our shelves quite aggravating since I might potentially have two (or MORE) locations for a given part (we stockall our parts by manufacturer, and then alpha-numerically).

      ANYWAY…

      the board you’re needing looks like this one…which has (as PartsTown indicated) had a part number change.  The one I’m linking below is for a SCCWE202 electric unit, so don’t use it as a reference for the part you’re needing to order:

      42.00.080P CONTROL PCB

      • nafets47

        Member
        January 24, 2020 at 10:50 am

        Well damn. Now I feel a bit confused.

        This is how I came to believe its the part I need.

        First I looked at the manual for the part number of the board which states it is 42.00.160 (attached)

        That part is not available on PartsTown …. or anywhere. However on Heritage Parts it has the data about said board, stating it has been replaced by 42.00.080P (attached). And also that it is obsolete but no alternative on Heritage Parts.

        Looking that part number up on  PartsTown says that 42.00.080P has been replaced by 42.00.260P

        • ectofix

          Member
          January 24, 2020 at 10:59 am

          That’s unfortunately the ways of Rational. 

          They’d probably initially designed specific boards that were suited for each of their various oven configurations (e.g., gas vs electric heat, countertop vs floor models).  THEN (it appears) they came out with ONE board to cover them ALL.

  • nafets47

    Member
    January 24, 2020 at 11:03 am

    Seems like it.

    So before jumping the gun… again.

    I emailed Rational asking them for which board is required to replace the 42.00.160

    • ectofix

      Member
      January 24, 2020 at 11:17 am

      I just checked their latest parts price list.   42.00.260P is the part you need.

      Here’s that list.  Look on page 119:

      Service Part-Price List April 1st 2019

      In THAT publication, you will find that they don’t even list 42.00.160.  Rational does THAT kind of BS too.  Namely, LOSING part numbers so that they don’t even appear in newer price lists.  That’s why I’ve them from every year – so I can look at an earlier one if Rational if Rational inadvertently fail to list an older number.  I usually will find an unlisted number in an older parts price list.

      So, look at my picture showing a part number change in a 2018 copy.

      Appears that board’s part number changed two or THREE times.

  • nafets47

    Member
    January 24, 2020 at 12:36 pm

    Great. Thanks a lot for that.

  • nafets47

    Member
    January 24, 2020 at 12:37 pm

    How does one get the parts price list? Is that something you sign up for?

  • olivero

    Member
    January 24, 2020 at 1:23 pm

    Wow, that’s insane.

    How is one supposed to keep track of these things?

  • nafets47

    Member
    January 24, 2020 at 5:22 pm

    Thanks etcofix.

    • ectofix

      Member
      January 24, 2020 at 7:01 pm

      I’ve sent @olivero an email which he can forward to you.

  • nafets47

    Member
    January 25, 2020 at 11:50 am

    Thanks he forwarded it to me.

    I really appreciate all of your help on this.

  • nafets47

    Member
    January 28, 2020 at 10:55 am

    So my new PCB arrived, installed and the screen fired up.

    Got a Service 17 error so need Rational to answer the phone and send me a data patch, apparently the install didn’t provide all the data so need to run some recovery software.

    • olivero

      Member
      January 28, 2020 at 11:36 am

      Hallelujah.

    • techtownmayor

      Administrator
      January 28, 2020 at 1:09 pm

      Congrats! Hopefully, the patch will be the last piece of this puzzle!

  • nafets47

    Member
    January 28, 2020 at 1:51 pm

    I hope so. If Rational would answer the phone!

  • nafets47

    Member
    January 29, 2020 at 8:29 am

    So, it is finally…..

    FIXED!!!!!!

    • fixbear

      Member
      January 29, 2020 at 3:17 pm

      Nice!!!!!!

    • ectofix

      Member
      January 29, 2020 at 4:38 pm

      Thanks for the update!

      This was certainly a learning experience for me as well and I feel more prepared to address such issues if one of our White Efficiency ovens goes bonkers.

      • fixbear

        Member
        January 29, 2020 at 6:58 pm

        Gotta love one that is a challenge.  I think we all learned a bit from this one.

        • nafets47

          Member
          January 30, 2020 at 11:30 am

          Definitely learning experience.

          Thank you ectofix and fixbear.

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