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  • Blodgett DFG-200  Low Fan Oven Mode Not Working

     fixbear updated 2 years, 4 months ago 1 Member · 31 Posts
  • guest

    Member
    September 17, 2017 at 12:00 am

    Hi Folks,

     

    I’m going to be working on a #Blodgett #DFG #DFG-200 convection oven today.  It has the Digital Solid State controller (controller is 1 yr old).  It had an issue where the “Oven On – High Fan” mode was working intermittently.  When I replaced the mode selector switch (got part # from parts manual) the switch was not same-for-same…  but similar and with prongs on the back marked L1, N, and then 1,2,3,4 (as the old one did).  Problem was… when I put it back together, the modes were not in the right order.  

    Old Modes (as labeled on the oven):  Top=Off, Right=On-Low, Bottom=On-High, Left=Cool Down

    New Modes:  Top = Off, Left = On-High, Right = Cool Down, Bottom = Off

     

    Bakers are complaining now that they need low fan mode to work…   I’ll have a chance to get to the oven soon…  got the Sequence of Operations and the electrical drawing but I’m wondering if there’s anything else to check?  My instinct tells me that someone used the incorrect mode switch last time and just re-wired it to work right…  and I’ll have to do the same with the new switch.  Of course I lost track of the old switch so I can’t just use a multi-meter to figure out if it was apples to apples  <facepalm>  

     

    Any advice greatly appreciated!!  

  • ectofix

    Member
    September 17, 2017 at 5:30 pm

    Sorting out Blodgett’s evolving array of control panels is about as clear as mud.

     

    So before I delve into this too far, let’s be sure of the control panel you’re talking about.  You said “Solid State” and Digital”.  Does this look like the control panel you have?

     

  • wired1000

    Member
    September 17, 2017 at 6:05 pm

    Yes that’s the one.  So…   I’ve made some additional “progress”:

     

    1)  Noticed that I had ordered a 3-position switch instead of a 4-position.  This is why the positions seemed off and why one wasn’t working (Why the 3 position switch STILL has FOUR positions and FOUR connectors on the back is a big mystery!!!)   

    2)  Decided based on wiring diagram that I could get the desired “Low Fan – Cook” setting to work if I changed some connectors around… so I removed the high-fan connectors from 4 and 2 and connected the low fan wire to position 4 on back of the switch.  

    3)  Plugged it back in…  tried it:   No dice.  I checked the relay…  it is engaging after a few seconds of the power being applied (and the controller powers on) but the fan is not coming on.  

    4)  Powered everything off again, cleaned the contacts on the relay…  tried again.  Still nothing.  

     

    That’s where I’m at at this point…  appreciate any help!!

     

    PS:  I misremembered the positions of the “Old Modes” switch in my first comment…  switched Cook High and Cook Low….   but at this point it’s not important since it’s the wrong switch… that problem is solved!!

     

    PPS:  Would be interested to know if there is a way to specifically check the low speed of the fan.  Is there a place I can just apply 110V to that would get it spinning or tell me if it’s shot?

  • ectofix

    Member
    September 17, 2017 at 7:22 pm

    If the relay is changing state, then the motor should go to low speed.  Certainly check that relay’s output with a meter.

     

    Just so you know, the side panel can be removed to expose a terminal board to which the motor wires to.  All of the wire colors are there per the schematic.  Looking at the schematic on page 2-11 of the service manual and assuming the relay depicted is in a de-energized state:

    • High speed = neutral to the motor’s black wire and line to the motor’s blue wire.
    • Low speed = neutral to the motor’s white wire and line is to the motor’s yellow wire.

     

    Worth noting is that a motor capacitor only exists on two-speed motors.  Single speed motors don’t use a capacitor.  So be sure to check the capacitor.  It’s located behind the control panel.

     

    FWIW:  I’m questioning that schematic because it isn’t making sense.  I’m not seeing line going to the motor during low speed.  Their illustration of the 4-position rotary switch leaves some questions.

  • wired1000

    Member
    September 17, 2017 at 7:30 pm

    Where would I check relay output?  I was kind of unclear on that…  

     

    How would you suggest checking the capacitor?  Actually I may have a spare of the capacitor…  but if it was failing wouldn’t both speeds be not functioning?

  • fixbear

    Member
    September 17, 2017 at 7:34 pm

    Wired1000,  They use 15 different controls on this oven depending on year and serial number.   A small bit of clarity here would help.  I only found 2 with 4 position selector switch.  What does your label on the switch say.

  • fixbear

    Member
    September 17, 2017 at 7:54 pm

    If it is the one ecto shows,  Violet 4 goes to L1,  violet 3 to 4, 

    Black7 to 1,  Violet 4 to 2,  Black1 to N,   and blue 1 or 4 (year) to 3

     

    L1/1 has to be closed to energize the low power fan relay.

  • wired1000

    Member
    September 17, 2017 at 7:57 pm

    Apologies.  The oven was built in 1991.  

  • wired1000

    Member
    September 17, 2017 at 8:00 pm

    We determined I purchased the incorrect (3 position switch).  So that wiring configuration doesn’t really help with the wrong switch.  I did figure out a workaround to get power to the low fan cook circuit but something else is wrong…  see above

  • wired1000

    Member
    September 17, 2017 at 8:02 pm

    Well I knew I had that capacitor spare so I dug around…  found I also have a spare for the relay.  I hate to just throw parts at things but they were right there!!  

     

    No joy…  no change from earlier configuration with the old relay / capacitor.  :-/  

     

    Also, checked out the side panel.  In the case of this oven the side panels have been welded in place.  Thanks Previous Owner!!

  • wired1000

    Member
    September 17, 2017 at 8:22 pm

    Serial#:  030194EA014B

     

    Not sure if it matters for this issue but the oven was converted from original Propane to Natural Gas at some point prior to me owning it.  

  • fixbear

    Member
    September 18, 2017 at 8:21 am

    That shows manufacturing date of march 1 1994 and a bottom oven, 14th built

    The 54447 is the right switch

  • fixbear

    Member
    September 18, 2017 at 8:37 am

    be aware, that Blogett had 2 different 4 position switches. 20347 and 54447.

    This is the switch positions FOR THE RIGHT ONE by the wiring diagram.

    Header 1 Header 2 Header 3 Header 4 Header 5
    switch position L1-1 L1-4 N-2 N-3
    OFF O O O O
    COOK HIGH 0 X O X
    COOK LOW X X O X
    COOL DOWN O O X O

    Either way with the cool down L! will work. one high, one low

     

    The cook and hold one does this

    Header 1 Header 2 Header 3 Header 4 Header 5
    Switch position L1-1 L1-4 N-2 N-3
    OFF O O O O
    COOK O X O X
    COOK AND HOLD X X O X
    COOL DOWN O O X O

     

    Note that the hold would cause a problem.

  • fixbear

    Member
    September 18, 2017 at 8:55 am

    FWIW:  I’m questioning that schematic because it isn’t making sense.  I’m not seeing line going to the motor during low speed.  Their illustration of the 4-position rotary switch leaves some questions.

     

    That’s because the N terminal goes around through the temp, time controller.  Both poles of the selector switch are not connected, but independent.  In low cook  L1 powers both 1 and 4 to drop the motor relay to low powering motor terminals 5 and 6 instead of 1 and 2.  Or if you prefer, motor plug pins 6 and 12 are high motor.  Pins 3 and 11 are low.  Pin one is the capacitor to both start windings.  They connect to motor terminals 1 and 6 threw the start winding’s.

  • fixbear

    Member
    September 18, 2017 at 9:09 am

    didn’t come out of a prison, did it?

  • fixbear

    Member
    September 18, 2017 at 5:29 pm

    You  can easily test your old switch to confirm if it is the problem.  I suspect that the relay coil or a plug is what you will find.

  • guest

    Member
    September 22, 2017 at 5:23 am

    I’m coming late to the party, here. Why did you feel the switch was bad. I was wondering if maybe the low speed windings, on the motor, had failed.  Intermittent high speed problems can also be the centrafugal switch, in the motor, starting to fail. Belive me, this one has caught me once or twice, too.

  • ectofix

    Member
    September 22, 2017 at 6:26 am

    Thanks for your input, rico.  However, in this application (convection ovens) the centrifugal switch doesn’t have anything to do with starting the motor.

    The centrifugal switch is normally OPEN – and then closes when the motor reaches operating RPM.  This energizes the oven’s heat circuit.

  • fixbear

    Member
    September 22, 2017 at 12:56 pm

    In all my years of working on food service, I have never seen a open winding on a convection oven.  Nor a shorted winding.  This is due to the high quality of insulation required for the heat and the high power factor for all the starts that a oven goes through.  Now bearing’s,and proofing switches,  that’s a different story.  Anyone have a different experience with them?

  • guest

    Member
    September 23, 2017 at 5:37 am

    Unfortunatly, I have seen both, otherwise I would not have mentioned them. I have had the low speed windings fail on two Blodgett unit. Granted this was over a 10 year period with four units in each of my twenty five restruants, so a pretty low number. But its the odd ball ones that usually trip us up 

    As for the switch I have had bad motor proving switches that would intermittently drop out the heat. You could turn the unit on and, no heat. Open the door, close it, and now its heating. Out of all those ovens I only had to replace three selector switches.

     

    I must have missed something. It was not clear, to me, if he was saying that it would not heat or that the blower motor would not run, in high.

  • wired1000

    Member
    September 27, 2017 at 2:02 pm

    Hi Folks,

     

    I really do appreciate the advice and ideas.  Just returned from vacation

    and had a pile of spare parts available to me that had arrived while I was

    gone.  Luckily, first one did the trick.  I replaced the 4-position switch

    with the correct # and everything is working fine again.  It must be

    something about the internal wiring of that 3-position switch that wasn’t

    allowing the low fan mode to work.??

     

    Anyway, thanks again.  Glad it was something simple…

  • fixbear

    Member
    September 27, 2017 at 3:53 pm

    Thanks for letting us know.

  • ectofix

    Member
    September 27, 2017 at 5:59 pm

    I kept thinking that putting the correct switch back in would be a good start.  Glad you got it resolved.  Thanks for the update.  Coincidentally, your problem help us resolve our own.

     

    After recently studying the oven’s circuit for YOUR problem, we had a similar issue.  I’m an in-house technician at a VERY large property.  Our shop is actually called “KITCHEN MAINTENANCE” and our work is dedicated solely to maintaining the many kitchens we have.

     

    Anyway.  Soon after your post, a co-worker was troubleshooting intermittent issues with a Blodgett oven’s blower motor occasionally not running.  It was the bottom oven in our oldest set of Blodgetts.  It just so happens to be as old as yours and with the same control panel.  What a coincidence…

     

    SO, after he’d looked at it…he was suggesting to me that maybe the motor needs replaced.  I told him that “I seemed to remember” that there’s a relay in there which controls motor speed and that he should take a look at that relay.

     

    A few days later, he approached me and said “YOU were right!”

     

    I said “What are you talking about?”

     

    He said  “In that Blodgett oven I told you about.  The relay was why the motor would occasionally not run”.  He showed me the twenty-something-year-old ice cube relay he’d removed.  Its contacts were seriously pitted.

     

    I said “Oh! Okay then.  Well…you’re ALWAYS telling me that I’m right!  PLEASE quit doing that and tell me when I’m WRONG instead!  I need to know THAT!”

     

  • wired1000

    Member
    September 28, 2017 at 10:11 am

    HAHAHAHA awesome, well glad it helped!!  Relays are always a weak point…

  • fixbear

    Member
    September 28, 2017 at 11:17 am

    I like to change them to ones that have a LED indicator.  Helps in knowing what is happening.

  • john

    Member
    September 28, 2017 at 11:39 am

    Forgive my lack of knowledge, but what do the LEDs indicate in this case? That the relay is/isn’t making contact?

  • fixbear

    Member
    September 28, 2017 at 12:49 pm

    You can buy ice cube relays that have a built in LED to tell you when the relay is energized.  A big help if you are working on something that has a large relay logic system and you have a intermittent problem.  The LED is just tied in with the armature coil of the relay. The spec’s have to match like control voltage and contact load current.  They usually run about 1 to 2 dollars more that original.  And it’s fun to watch the Christmas Tree effect.

  • ectofix

    Member
    September 28, 2017 at 6:48 pm

    Relay logic?  WELL,  NOW I gotta share something.  Here’s a smoker we have that once used relay logic.  These pictures are from a few years ago:

     

     

    This unit is the older of our two smokers.  It (and its 2014 brother) will literally smoke a ton of meat each…in a single cook cycle.  The smoke is piped in from a separate smoke generator (which burns sawdust) attached through a rather longish 6″ diameter flexible duct.

     

    It cooks in programmed stages.  The time or temperature-controlled cook stages are tailored to the specific products being cooked…or so the smoker to do a cleaning cycle.  Yes, it washes itself too. 

     

    This mid-nineties vintage unit was designed with chill coils for cold-smoking too.

     

    So along with this smoker actually bringing in the smoke, the programming (and all those little relays) introduces steam, electric heat from internal elements, varies the convection fan speed, sprays in a soapy solution or just water during a cleaning cycle, brings in chilled water through coils to cool the 6’x6’x8′ cooking compartment.  I think there are additional relays there for other functions which this smoker wasn’t outfitted with.

     

    A few years ago, this old relay logic system was upgraded to a PLC system when Enviro-pak was here to get our newly purchased, identically-sized unit up and running.  I only have pictures  of THIS unit though…including some pictures after its upgrade…which I don’t see a need to share here.  Enviro-pak left allot of the old stuff behind during the upgrade (note the now-defunct chart recorders and bank of toggle switches) – so despite its revised controls, it’s still VISUALLY not clean or streamlined-looking enough to impress anyone.  

     

    When I get a chance, I’ll take a picture of the guts of the NEWER smoker.  The stark contrast between this OLD unit’s mess of wires and relays when compared to the simplicity of how the NEW unit looks…is amazing.  The new one also has a VFD for the convection blower motor control.  The old unit still employs contactors to switch motor speed.

  • fixbear

    Member
    September 29, 2017 at 2:19 pm

    Nice, but who ever worked on it did’t bother to reinstall all the wire way covers.  Looks like a few added jumpers.  Graph wiring clamps missing o the wires get pinched in the door. A a few hot fuses.  Had to be built before the manufacturer adopted I-O programmable controllers.  Love the french Crosiat relays. 

     

    I once recommissioned a portable rock crusher in Orting, WA.  that had been canibilized and had no wire markings.  There was two of these units that came off a bankrupt job in California.  The dealer kept the better one for himself and my previous employer enlisted me.  My flights, tool purchases, rental car, hotel,  parts and labor for 5 days came to about $15,000.  The dealer brought in a team from Sweden to fix his and spent $165,000. let alone they took 3 months.  468 page wiring diagram. 380 relays, Calibrated resistor blocks.  They did provide me with pictures of the panel prior to my accepting the job,  But it took a whole day of reading the wiring diagrams and parts manual, making a full list to send a runner for tools, Odering relays from NJ.  And using one of my suppliers from the east coast for overnight on the relays. Manufacturer (Sweden) and dealer had nothing and wanted 3 weeks to deliver.  Non off the shelf items I found a panel builder up in Everett that loaned me a table to make resistor blocks. And lables.  Sure wish I had taken pictures like ectofix does.

  • ectofix

    Member
    September 29, 2017 at 9:48 pm

    fixbear wrote:

     

    468 page wiring diagram. 380 relays, Calibrated resistor blocks.

     

    WELL…in the world of relay logic, I’d figured this smoker-oven was rather simple.  Now I’ll just categorize it as “Relay Logic 101”.

    I’m curious as to what its PLC variation looks like.

     

    fixbear wrote:

     

    Sure wish I had taken pictures like ectofix does.

     

    Much of the convenience afforded by snapping a quick photo using a smartphone has yet to be realized by us old farts.

     

    For instance:

    When I go to our warehouse to  pluck a part out of a bin, I gotta go write its rather lengthy stock number down onto a list when I get up to the counter.

    I learned that NOWADAYS – instead of writing that bin box number down into my notepad…to then walk w-a-y up to the counter to write down AGAIN onto the warehouse manager’s clip board – INSTEAD…out comes my smartphone to snap a quick photo of the bin box’s number, then leisurely go jot the number down from what I took a photo of.

     

    STUPIDLY simple.

     

    I can’t convey the numerous OTHER ways in which taking a quick digital picture has made things SO much easier…when compared to ten years ago.  It seems that I discover how to capitalize on it’s benefit more and more everyday.  I pretty much take several photos a day to communicate whatever I need to- to someone.

     

    After all, a picture is worth a-thousand words.

     

    fixbear wrote:

     

    Nice, but who ever worked on it did’t bother to reinstall all the wire way covers.  Looks like a few added jumpers.  Graph wiring clamps missing o the wires get pinched in the door. A a few hot fuses.  Had to be built before the manufacturer adopted I-O programmable controllers.  Love the french Crosiat relays. 

    All done before my time.  Aside from correcting all that, I’d like to strip out or blank out the superfluous stuff too.  The charts.  The toggle switches.  The extra temp probes.  Other things.  But…

     

    Ain’t nobody got time for that!

  • fixbear

    Member
    September 30, 2017 at 7:22 am

    Chart recorders used to be required when you produced food in the danger zone.  As well as monitoring available water in the product.  If one was making a bunch of bacon or sausage or any other cured meats for off site sales you would still need them.  After all, Salt Petre (potassium nitrate) is going as a thing of the past.  To easy to make gunpowder with and still the surest for a safe cure.  But today they have made it had to get and are forcing producers to go to Prague powder 1 or 2. also called Instant cure. A combination of sodium nitrate, sodium nitrite, and salt. The salt locks up the water and the cure lowers the ph below were bacteria can survive.

     

    Basically, the machine worked on the wire of food safety. That’s why all the probes, sensors and monitoring.I don’t know what your kitchen is using it for, but i’ll wager no where near it’s design use.  Love to have acsess to one. Get to make real cured meats.  Not todays garbage.

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