Question for Electrical Geniuses -- Multipole Switch

[Dockhead]

My boat was built with a Eumenia/Eudora EU457 washer/dryer. The cabinets in the passage cabin were specially built to accomodate it.


As my boat is going on 19 years old, and I've spend significant stretches living on board during my almost 11 years of ownership, this device is getting a bit long in the tooth. I would love to replace it with something new and of more modern design (with heat pump dryer for example? which uses less water?) but it's impossible without rebuilding those cabinets which would cost a fortune.


And anyway the Eudora is actually a fantastic machine -- super heavy duty, has been nearly flawless all these years, and I guess will last a few years more. HOWEVER -- one component has failed, which is not available anymore.


It's a complicated rotary switch. The contacts which run the dryer are burned or worn. The schematic of the switch is like this:





I would have thought that I could just transfer the dryer functions to a different rotary switch, but I don't really understand what connects what together here. I would only need to do "Trocknen Normal" -- normal dry, the last line in the schematic.



How to read this schematic? An "x" means the numbered terminal plus its corresponding "a" are connected? Or what? So that on "Trocknen Normal", there would be connections made between 1 and 1a, 2 and 2a, 3 and 3a, etc., or what?

[YANDINA]

If the switch is a manual switch that selects different washing profiles, pick the one that you use most of the time and hard wire the connections together according to the switch diagram and from analysis of the old switch.

If it is a motor driven switch that cycles through the stages you are up switch creek.

[Wotname]

Originally Posted by Dockhead

............
How to read this schematic? An "x" means the numbered terminal plus its corresponding "a" are connected? Or what? So that on "Trocknen Normal", there would be connections made between 1 and 1a, 2 and 2a, 3 and 3a, etc., or what?
.......

That would be my understanding and continuing with 4&4a but not 5 or 6 or 7 or 8.
Then 9 through to 12 will be connected to the corresponding 9a through to 12a as well as 14 to 14a. 13 and 15 through to 20 will be open circuit to their corresponding "a" contacts.

[rslifkin]

Even if the old switch isn't working properly, it may still be making good enough contact to pull it out and use an ohm meter to map out what's connected to what in various positions to confirm you're reading the diagram correctly.

[Wotname]

Looking closer.

If you only want AUS and Trocknen Normal, then you don't need to operate contact set number 3 as it remains closed for both AUS and Trocknen Normal.
The other eight sets of contacts (1,2,4,9,10,11,12,14) need to be closed for Trocknen Normal and opened for AUS.

[Dockhead]

Originally Posted by Wotname

Looking closer.

If you only want AUS and Trocknen Normal, then you don't need to operate contact set number 3 as it remains closed for both AUS and Trocknen Normal.
The other eight sets of contacts (1,2,4,9,10,11,12,14) need to be closed for Trocknen Normal and opened for AUS.

OK, did I understand the circuits correctly? Each of these is an isolated set of contacts?


I know I could pull it all apart and check with an ohmmeter as someone above suggested, but I'd prefer to understand it via the schematic first.


If that's true, then it would seem to me that a 5 pole, 2 position switch, joining contacts 9, 10, 11, 12 and 14 might do the trick.


I don't think contacts 1, 2, 3 or 4 are the problem. Because (a) 1,2,3 are shared with washing functions, and washing is flawless; and (b) the problem exists with both Trocknen Schonend and Trocknen Normal, so can't be 4.



What do you think?

[Wotname]

Again, to simply go from AUS to Trocknen Normal, you need a 8 pole single throw switch (or two 4 pole single throw switches ganged together).

The only concern (possibly) is whether you need to cycle through the some of the other rotary switch positions before getting to Trocknen Normal for other parts of the circuit to work. Given the age of the design, I guess this won't be an issue!

[Dockhead]

Alternatively, I guess I might try to find the burned contact, and put a relay in that circuit? The switch probably carries enough power to trigger a relay.

[Wotname]

Originally Posted by Dockhead

OK, did I understand the circuits correctly? Each of these is an isolated set of contacts?


I know I could pull it all apart and check with an ohmmeter as someone above suggested, but I'd prefer to understand it via the schematic first.

Yes, look at the full schematic and you will find all of the 20 isolated poles in various parts of the circuit.

Although it does look like some of the contacts maybe normally closed i.e. contact sets 5 & 6 and 12 through to 17.

It's late here so I will look again in the morning - if someone else hasn't given a more definitive answer regarding contact sets 5 & 6 and 12 through to 17.

[Dockhead]

Originally Posted by Wotname

Yes, look at the full schematic and you will find all of the 20 isolated poles in various parts of the circuit.

Although it does look like some of the contacts maybe normally closed i.e. contact sets 5 & 6 and 12 through to 17.

It's late here so I will look again in the morning - if someone else hasn't given a more definitive answer regarding contact sets 5 & 6 and 12 through to 17.

Thank you!

[Dsanduril]

If your machine is the same as ours (can't remember exact model) then there are three knobs? One to set temperature (left), one for some options (right) and then one in the middle for cycle/function? And that one is motorized (moves by itself during the cycle as is goes through steps)?

I would concur that contacts 1-3 are probably good, they supply power to the whole machine, and you say washing is OK. So I'd look at contacts 11 and 12, these go to the heating element (HZG) for the dryer (looks like they use a separate element for the washer - surprised). Drawing location 6B. The element appears to be controlled by a potentiometer 0-95C. [Edit], as I look further, I think the HZG at 2B is the dryer HZG (which makes more sense from a temperature range), which means 4/9/10 in B2-4 are the likely power culprits for that HZG. It looks like 4 and 9 control power for the heater, so I'd start with those. Also note the 2 80C temperature switches in the line. If either of those are tired then the heater won't run - they'd certainly be easier to deal with than the rotary switch.

Switch 4-4a is normal/high drying, if the dryer works on low dry (the 50C temperature switch then comes in/out rather than 4-4a) then 4a is a problem. If the dryer doesn't work on either setting then I'd lean toward 9-9a.[/edit]

Looks like 14/15 control the drum rotation/speed, so these should also be fine.

Leaving 9/10 as also possible suspects.

Don't think it matters, but 5-6, 12-13, 14-15, 16-17 are SPDT contacts, only one set can be active at a time (i.e. if you have 5-5a you can't have 6-6a).

At the bottom of the drawing (row E) there are a bunch of numbers, I think these are cycle position numbers.

[Ivansgarage]

what is the part number on the switch

https://www.appliancepartspros.com/s...=307054&page=3

[Dsanduril]

I've been thinking about this as I work on other things, my mind is now suspecting the 80C thermal switches as the most likely culprits. It looks like 4-4a and 9-9a would be static during the drying cycle, while the thermal switches would cut in/out, under full load, in order to maintain temperature. This would probably affect low dry as well, if they failed open then low dry would not work.

As a very short TEST you could jumper around the 80C switches. These are safety devices (that's why two in series) so the only purpose would be to determine whether or not the heater element comes on. Easiest way to evaluate that would be power draw, either at your main panel or a clamp meter. Either way, if you jumper those and power draw goes way up then the heater is working. If you remove jumper and no power draw then the switch(es) are bad.

Could use the same testing around 4a-4 (although if this is the problem then low dry should work) and around 9-9a.

If the symptoms include the drum not spinning during dry then I would look at the switch located at 1/2 B/C on the drawing. In dry mode that switch moves to 1-4 and provides the neutral connection to the dry circuit. Along with 14-14a it also provides neutral to the drum. The same switch, at position 1-2, along with 15-15a provides neutral in wash mode.

[Dockhead]

Originally Posted by Dsanduril

I've been thinking about this as I work on other things, my mind is now suspecting the 80C thermal switches as the most likely culprits. It looks like 4-4a and 9-9a would be static during the drying cycle, while the thermal switches would cut in/out, under full load, in order to maintain temperature. This would probably affect low dry as well, if they failed open then low dry would not work.

As a very short TEST you could jumper around the 80C switches. These are safety devices (that's why two in series) so the only purpose would be to determine whether or not the heater element comes on. Easiest way to evaluate that would be power draw, either at your main panel or a clamp meter. Either way, if you jumper those and power draw goes way up then the heater is working. If you remove jumper and no power draw then the switch(es) are bad.

Could use the same testing around 4a-4 (although if this is the problem then low dry should work) and around 9-9a.

If the symptoms include the drum not spinning during dry then I would look at the switch located at 1/2 B/C on the drawing. In dry mode that switch moves to 1-4 and provides the neutral connection to the dry circuit. Along with 14-14a it also provides neutral to the drum. The same switch, at position 1-2, along with 15-15a provides neutral in wash mode.

Yes, drum does not spin when it fails.



But I don't have any issues in wash mode, so could it be that switch?

[Dsanduril]

The way I read it that switch controls leg 2 of the mains power. Normally neutral but according to the drawing the machine doesn't care which leg is neutral and which hot.

I suspect that switch is piggy-backed on the rotary switch. When the connection is made 1-2 the neutral is connected brown-blue and the wash functions have power. When that switch is connected 1-4 the neutral is connected brown-violet and the dry functions have power.

In dry mode 14-14a then provide neutral to the motor/drum controller. In wash mode 15-15a provide the same function.

So, in short, yes, I would say the problem could be that switch. Testing would be as simple as putting the rotary knob in dry and then jumpering brown-violet.

There could be other interlock logic that prevents the drum turning when no heat, I don't see it, but some of the other switches are a bit opaque/mysterious as to function.

One more test before opening things up, does it not work in low dry mode as well? And does the drum not spin?