Sonach drinking water heater not working

[Welchs101]

hi,

was not sure what forum to go to but thought i would try this one.

My parents have this device for drinking hot water. It sits on their counter and they press a button and it gives hot water. well it stopped working. they asked me to take a look at it. basically, it just quit heating the water. i could see lights on the unit when i press buttons but the water would not heat.

i took it apart and found this IC board links to pics (i had to use photo-bucket links...could not upload for some reason)





if pics dont come through just let me know and i will try again.

what i did thus far:
I used a multimeter and just went around the small board and started checking stuff. I started with the diodes. I found that the diode next to the big black "box" was not shorted but measured about 470kOhm. I removed the diode only to find out that it then measured fine......like a normal diode. SO this led me to focus on the big black box thing.

The part number on the big black box was "YX202-S-112DM". I did a quick search and well.........i am not sure what this thing is. I think its a relay but not sure. the black-box basically has 4 leads on it. Two of the leads appear to be inputs and are taking the power bascially from the power cord that goes to the wall....i think. THe other two leads measure the 470Kohms that i orginally measured across the diode....

any thoughts? is the relay bad? is this thing even a relay?

[joshnz]

Re: Sonach drinking water heater not working

I would say it is a relay with normally open contacts.
do you hear a click when you try to heat the water?

[joshnz]

Re: Sonach drinking water heater not working

Also can you provide a picture of the bottom of the board please.

[Welchs101]

Re: Sonach drinking water heater not working

here is a picture of the back of the board




also note: i measured the resistance between pins 1-2 and 3-4.

Pins-1-2: is ~ 400 ohms
Pins-3-4: is open


pins 3-4 are where the "power" comes in.......my guess is the output of the relay is on pins 1-2. If this is a relay "noramally open" should i be measuring 400ohms on pins 1-2 when no power is connected to the board?

is this relay bad? if so what replacement should i get?

[selldoor]

Re: Sonach drinking water heater not working

Anything to do with heating water its best to test the heating elements first.
Resistance good - no resistance bad - resistance element connector shorted to ground bad.

[capkid]

Re: Sonach drinking water heater not working

Yeah, if it turns on and seems to otherwise function normally, I'd look at the heating element as a possibility.

[Welchs101]

Re: Sonach drinking water heater not working

ok.....not sure where that is yet but i will look for it and get back to you guys.....but just curious about the relay .......should it measure 400ohm between pins 1 and 2?

[SeanB]

Re: Sonach drinking water heater not working

It will read that, as those are for the internal coil. Likely the relay is faulty, they often fail and are cheap and easy to get as spares. The relay will be either a 12V or a 24V unit, likely a 12V one and the mains transformer will be a 9VAC unit.

Check the heaters and the thermal fuse in the lead to the heater as those are also failure prone. If the heater you need to get a new one from the agents, but the relay and the thermal fuse are common parts.

[budm]

Re: Sonach drinking water heater not working

Pin 1 and 2 is the relay coil, DCR of 400 Ohms for 12VDC Coil is about right for this relay. pin 3 and 4 are for the N.O. (Normally Open) contact. I would check the heater core and it should also have have some kind of thermal cutoff switch for the heater for safety. Pictures of the whole unit? The Diode in parallell with relay coil is for snubber.
https://cdn.badcaps-static.com/pdfs/...ffbf8ae00e.pdf

[Welchs101]

Re: Sonach drinking water heater not working

thanks all.........i have not had much time today to dig into the heater.....apparently the heater coil is deep in side the unit....will take some time to get to it.....

but thanks!!!!!!! for the help thus far

i will keep you udpated as i work on it

[Welchs101]

Re: Sonach drinking water heater not working

hey just out of curiosity.......i tried looking up the relay that in one of the posts sent in a pdf........but i cant find it on digikey or newark.......anyideas?

again, once i get a look at the headter coil i will make an update

[budm]

Re: Sonach drinking water heater not working

At this point, you can bypass the relay contact by putting the jumper between 3 and 4 but I will not do that until you verify that the heater, thermal cutoff are OK, if they are OK, then the heater should be hot when apply 120V to the unit.

[joshnz]

Re: Sonach drinking water heater not working

Just some info

[Welchs101]

Re: Sonach drinking water heater not working

ok.......i finally got to the heater.....or what i believe is the heater.

i am showing a picture of what i think the heater is. There are two of these. I measured across the terminals on one of them and measured a short 0.5ohm. I measured the other one and measured 275ohms.

but where would i find such a thing......any ideas

[Welchs101]

Re: Sonach drinking water heater not working

ok....so pic may not be inserted correctly

[budm]

Re: Sonach drinking water heater not working

That is the thermostat and should be connected in series with the heater if you trace out the connections.

[Welchs101]

Re: Sonach drinking water heater not working

ok.....but what about the resistance measurements i mentioned.........is that normal?

[budm]

Re: Sonach drinking water heater not working

So It has two of these thermostat? Both of them has the same P/N? Just want to make sure one of them is not normally-open type if it does not have the same P/N. Also you tested them by itself without nothing attach?
Picture of the heating element?

[momaka]

Re: Sonach drinking water heater not working

Try connecting a 9V battery to pins 1 and 2 of the relay and see if it makes a clicking sound. If the relay does click, try measuring resistance between pins 3 and 4 while the battery is still connected to pins 1 and 2. The resistance between pins 3 and 4 should then be very low (under 3 Ohms, depending on how low your multimeter can measure).
When you're doing this test with the 9V battery, put (+) of the battery on pin 2 and (-) on pin 1. Make sure that the diode you removed (D5?) is installed on the board before you do this, though, and make sure it is put back in the right way.
If you do NOT get any clicks from the relay with the battery, either remove the relay out of the board and test again with the 9V battery or remove the small transistor (Q2) next to the relay.

There's also a chance this may be a 24V relay. In which case, a 9V battery may not be good enough to test it. However, two 9V batteries in series should be.

Also, the 0.5 ohm reading you got is right for the thermal cutoff switch (i.e. this thing). The 275 ohms reading is right for the heating element.
I didn't quite understand your post, but if you have TWO thermal cutoff switches and one is reading 275 Ohms, then that switch is bad. Only the heating element should read that high in resistance.