Rational SCCWE62G dead

[olivero]

@Fixbear

@Ectofix

[ectofix]

@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]

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]

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]

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]

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

[olivero]

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]

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]

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

[olivero]

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]

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]

control transformer

See the fuse?

[olivero]

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]

Or this one depending.

[ectofix]

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]

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

[ectofix]

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]

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]

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]

I MUCH prefer hard-copies.

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

[fixbear]

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]

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]

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]

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

[ectofix]

I thought you said “LICKED”.

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

LOL!

[nafets47]

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]

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?