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[SOLVED] Unclear diagram for Stove Top (from manufacter)

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Nov 23, 2012
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Hello Guys

I just got myself a used oven with a separate stove top.
The stove top is a ceramic one and is connected to the oven via two terminal blocks.

Ofc the previous owner did not disconnect the terminal blocks from the oven but instead the cables them self from the blocks. So now there are seven loos cables that some how are supposed to go into the two terminal blocks. Luckily I was able to order the service manual from the provider. Yet, for me as a non-expert in electrical issues, I'm not able to clearly understand how it should be connected.

Cables from Stove top are to be connected to the terminal blocks W1 and W2 (see diagram), the question is what cable goes where? Seven cables from "AR" to W1 and W2 (VDD, VSS, RX/TX, L1, L2, N [blue], N [blue]). W1 and W2 are to be connected to the Oven that supplies power (400V 3N~). The connection scheme is provided from the manufacturer. On the pictures it is seen that all the cables are named, some only on the backside though (the two blue ones, "N" and the brown "L1" and white "L2").

Please see attached pictures and diagram.


Hope someone are able to solve the diagram unambiguous.


Looking at the schematic:

The two blue wires (N) appear to go to the bimetal devices. The board appears to have both N wires connected, so I do not believe it matters which blue goes to which bimetal.

L1 (red) is shown going to the common terminal at the burner icon.

Blocks W1 and W2 have several wires with duplicate labels. Your board shows only one of each such wire. It would make sense if your oven has either W1 or W2 (but not both).
If so then RX/TX (white) goes to one connector.
Vdd (brown) goes to one connector.
Vss (blue) goes to one connector.

I don't see a wire marked L2 on the schematic. Since it is white, I look at the table and see it is associated with the number 99. But there are two wires marked 99 on the schematic. So it is ambiguous.

Does L2 have any other name?

Sadly, no other marking... It is rather confusing that the naming on the drawing is different from that on the board. I do not now if there are any common standard associated with those markings that make this clearly.

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Never thought about checking the color coding of the other cables, might be a good idea. After some translation of the labels on German it gets a little clearer:
AR: Power electronics unit for cooker
V3: Electric cooking plate
W1: power connector [!]
W2: signal connector [!]
K8: Residual heat indicator light display
X2: Ground for cooker

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Okey, I have a theory for W2: Looking on the cables from the K8 (Heat indicator) they are all going to LA, LB, LC, LD, all of those if looking on the backside of the board seems to go up to the circuit arround RX/TX white, VSS blue and VDD brown which are all part of W2 (the controll connectors). For me it make sens that those are a part of a signal system? With other word: Vss blue to W2 Vss, Vdd brown to W2 Vdd and Rx/Tx white to W2 Rx/Tx? I dont really know how those cookers works so maybe it is not correct at all...

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For W1 the following seems to be possible: N (blue) and N (blue) goes to supplying two stoves each, on the other side of the cookers V3 they end up in terminals "A", "C" and "D", "B". It make sense that those two can be considered as positive supply and both goes to Vdd [230V~ phase 1] and Vdd [230V~ phase 2] (phase 3 is used bye the oven), even if I thought the stove worked on AC and not DC, but maybe the notations Vss and Vdd are used even for AC circuits. To confirm this theory and make the L1 and L2 unambiguous and to solve Vss and Rx/Tx on W1, there can be seen that K8 (the heat indicator) has four signal in lines and one ("II") going to terminal L1 that seems to be some kind of ground supply. From that my theory is that L1 can been seem as a ground supply (for both K8 and half of the V3:s (by looking on the backside of the board it can be seen that L1 is supplying two stoves and L2 the other two)) and therefore L1 should connect to Vss on W1 (Vss - negativ/ground supply) and the last L2 to Rx/Tx. It can also been seen that the soldering to L1, L2, N and N are much more robust than to the signal cables which also supports my theory. Considering the colours on the cables, white is according to my theory used to Tx/Rx both for W1 and for W2. Although, the blue cables make no sence. 2xN is blue and connected to Vdd on W2 and for the signal cable the blue goes to Vss instead. But maybe they use different color logic for the supply and the signals. Anyone agrees on this theory?
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I think I was incorrect to suggest L1 goes to the common for the burners. There looks to be a second L1 (black wire at the corner of the board) for that purpose.

The red wire going to L1 on the board is connected to a relay (or two). Likewise the white wire going to L2 on the board. This suggests they carry heavy current, although it is not necessarily to the burners.

I have never heard of a stove containing a transmitter/receiver (let alone two of them). So I can't offer informed opinion about the TX/RX wire.

The previous owner probably disconnected wires where he did for a reason. Do you think it was because they go to connectors that are 'quick' insert and release? Have you examined the modules to see if they will accept wires below a particular size? This would rule out the larger wires.

Can you see whether the modules have wire codes or color labels on them?
Maybe even a bit of insulation the same color as the wire you are considering re-installing?

No the modules have no color coding or other kind of coding. Yes the modules are of quick-insert and release type and i am pretty sure he disconnected the wires instead of the terminals because of that he was unaware of that the connectors where able to release and not fixed mounted. If he would just had disconnected the connectors it would have make everything very much more easy :) My theory is that W1 takes all the load, two are zero and two are phases. Probably the coding of Rx/Tx is just to sepparate the L1 from L2, even if it is in a kind of wierd way to do it in my opinion...

It's true you have 7 loose wires...

and the schematic shows 7 wires going to the W1 and W2 modules...

and 3 on your board match the W2 labels...

But it is still a question why the remaining 4 of your board's wires do not correspond to the W1 labels.

It is typical for an electronics manufacturer to make changes to a product, and not document them in the manual. However this would be an unbelievable case, when the board labels are so far off from the schematic labels.

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What's needed is additional schematics. They might be pasted inside the appliance somewhere.

Have you examined all around the inside of the housing? There could be a diagram showing how wires should go between the various modules.

Mad some measurements on the modules W1 from the oven, and the results where which works fine after connecting everything, Rx/tx - phase 1, Vss - zero, Vdd - phase 2, Vdd - zero, which does not make any sense at all. So I believe that you are right that they just change and updated this board since they made this manual... W2 are just to be connected to the labels on top of the board, they are all supplying low voltage signals. Thanks for the help everyone!

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(L1 I connected to the first phase and L2 to the second phase, the two blue cables to the zero lines)

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