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[Nickbat]

I'm a bit dim when it comes to circuitry, so apologies in advance! 

My dishwasher has packed up and I'm pretty sure that it is the inlet valve solenoid that's gone (it doesn't fill!). I checked on line and you can see if the solenoid is working by doing a continuity test. I set up my multimeter as described. It shows 1, then when the probes touch it goes down to zero. When I used the probes on the solenoid valve, it comes out with a reading of 1903. What's that all about?  :-?

Advice please!!

[Baron Von Spongebob]

Knowing you, it's probably the year you bought it..

[Nickbat]

Knowing you, it's probably the year you bought it..

There's always one...and it's always you.!! 

[Marks DTM Calib]

Well, 1903 could be the resistance reading....I assume you have it set to an ohms range and the power is off with the supply wires to the solenoid (at least one of) disconnected?

[zirk]

As Mark says 1903ohms, about 2k, assuming your DVM auto ranges, have you discounted the solenoid completely before measuring it. also measure it both ways to check you get the same reading.

No nothing about washine machines, but if its a 240 Volt driven solenoid, 2k sounds a bit high to me (120mA).

Chris.

[KillerWatt]

As Mark says, assuming you have the meter set to read resistance then the figure of 1903 will be the internal resistance of the coil.

However, just because it apparently reads OK....it doesn't mean that it is.

A further check would be to set the meter to read AC Volts, connect the meter across the solenoid, switch the dishwasher on, and you should see around 230V at the point the dishwasher is due to fill.

If 230V is present, then the solenoid is more than likely duff.
If 230V isn't present, then start looking at why the controller isn't providing it (eg, failed door interlock).

Above all, be very careful.

[Nickbat]

Well, 1903 could be the resistance reading....I assume you have it set to an ohms range and the power is off with the supply wires to the solenoid (at least one of) disconnected?

My multimeter has a symbol like Concorde flying left to right and a vertical line running just ahead of the wings ( ). From the website I looked at this is apparently the lone continuity setting. It did say you could check with evreything in situ, but I'll just nip down and take the two wires off and recheck the values. 

[Nickbat]

Checking the terminals of the disconnected solenoid, I get a reading of 1, so I guess it is fubared.

[zirk]

Checking the terminals of the disconnected solenoid, I get a reading of 1, so I guess it is fubared.

If its reading 1, thats a short, are you sure your measuring Ohms?

[KillerWatt]

Checking the terminals of the disconnected solenoid, I get a reading of 1, so I guess it is fubared.

If its reading 1, thats a short, are you sure your measuring Ohms?

A reading of 1 on a DMM is open circuit

[Kevin Wood]

Well, 1903 could be the resistance reading....I assume you have it set to an ohms range and the power is off with the supply wires to the solenoid (at least one of) disconnected?

My multimeter has a symbol like Concorde flying left to right and a vertical line running just ahead of the wings ( ). From the website I looked at this is apparently the lone continuity setting. It did say you could check with evreything in situ, but I'll just nip down and take the two wires off and recheck the values. 

That sounds like diode test mode (or continuity test). What you actually want to do is to test the resistance of the coil. If that resistance is high diode / continuity test mode may well not work as that mode is designed to look for short circuits or very low resistances.

If would say put it on an ohms range instead (perhaps 20k ohms or so, working down if the reading is very low) and see what reading you get.

If you let us know what model of meter you've got it might help.

Kevin

[Andy B]

.....
It did say you could check with evreything in situ, but I'll just nip down and take the two wires off and recheck the values. 

You've to check the solenoid/coil in isolation or else you'll be checking the rest of the circuit for resistance too. The resistance setting are those next to the Greek letter omega  ..... 

[Andy B]

Before you start playing .... what's your address? Just so we know where to send the emergency services!!     

[zirk]

Checking the terminals of the disconnected solenoid, I get a reading of 1, so I guess it is fubared.

If its reading 1, thats a short, are you sure your measuring Ohms?

A reading of 1 on a DMM is open circuit

If His measuring resistance of 1, then thats 1ohm, assuming its 240v driven, then 1 ohm accross 240volts? that to me is a short.

[KillerWatt]

Well, 1903 could be the resistance reading....I assume you have it set to an ohms range and the power is off with the supply wires to the solenoid (at least one of) disconnected?

My multimeter has a symbol like Concorde flying left to right and a vertical line running just ahead of the wings ( ). From the website I looked at this is apparently the lone continuity setting. It did say you could check with evreything in situ, but I'll just nip down and take the two wires off and recheck the values. 

That sounds like diode test mode (or continuity test). What you actually want to do is to test the resistance of the coil. If that resistance is high diode / continuity test mode may well not work as that mode is designed to look for short circuits or very low resistances.

If would say put it on an ohms range instead (perhaps 20k ohms or so, working down if the reading is very low) and see what reading you get.

If you let us know what model of meter you've got it might help.

Kevin

Every DMM I have seen goes in to diode/continuity mode when the lowest resistance range is set (eg, on mine..when I select the 200 ohm range..that is still measuring resistance, but it is also low enough for diode/continuity testing).

[zirk]

Before you start playing .... what's your address? Just so we know where to send the emergency services!!     

 

[KillerWatt]

Checking the terminals of the disconnected solenoid, I get a reading of 1, so I guess it is fubared.

If its reading 1, thats a short, are you sure your measuring Ohms?

A reading of 1 on a DMM is open circuit

If His measuring resistance of 1, then thats 1ohm, assuming its 240v driven, then 1 ohm accross 240volts? that to me is a short.

Read the original post again.
The number 1 will be on the left hand side of his display, which is indicating that the probes are not measuring anything.

[Nickbat]

Well, 1903 could be the resistance reading....I assume you have it set to an ohms range and the power is off with the supply wires to the solenoid (at least one of) disconnected?

My multimeter has a symbol like Concorde flying left to right and a vertical line running just ahead of the wings ( ). From the website I looked at this is apparently the lone continuity setting. It did say you could check with evreything in situ, but I'll just nip down and take the two wires off and recheck the values. 

That sounds like diode test mode (or continuity test). What you actually want to do is to test the resistance of the coil. If that resistance is high diode / continuity test mode may well not work as that mode is designed to look for short circuits or very low resistances.

If would say put it on an ohms range instead (perhaps 20k ohms or so, working down if the reading is very low) and see what reading you get.

If you let us know what model of meter you've got it might help.

Kevin

It's a Sinometer (cheap Chinese job, I think). Anyway, I have the solenoid here and I've turned the dial to 20k, at which I get a reading of 4.99.

On 200 ohms I get a reading of 1.

This is like a foreign language to me! 

[KillerWatt]

It's a Sinometer (cheap Chinese job, I think). Anyway, I have the solenoid here and I've turned the dial to 20k, at which I get a reading of 4.99.

That means the solenoid has an internal resistance of 5K ohms (5000 ohms)

On 200 ohms I get a reading of 1.

That simply indicates the meter is out of range.

[Nickbat]

It's a Sinometer (cheap Chinese job, I think). Anyway, I have the solenoid here and I've turned the dial to 20k, at which I get a reading of 4.99.

That means the solenoid has an internal resistance of 5K ohms (5000 ohms)

On 200 ohms I get a reading of 1.

That simply indicates the meter is out of range.

Thanks, KW, but is that good or bad?  :-?

[Kevin Wood]

It's a Sinometer (cheap Chinese job, I think). Anyway, I have the solenoid here and I've turned the dial to 20k, at which I get a reading of 4.99.

That means the solenoid has an internal resistance of 5K ohms (5000 ohms)

On 200 ohms I get a reading of 1.

That simply indicates the meter is out of range.

Thanks, KW, but is that good or bad?  :-?

That sounds about the right ballpark to me. It's not open circuit (the normal failure mode), at least.

Next question: does it get power when the machine is supposed to be filling?

Kevin

[zirk]

So what do we think Gents, 5k?, if its 240v driven sound a bit on the high side to me, works out about 50mA, Not enough to to switch a water solenoid me thinks.

[Andy B]

......
Next question: does it get power when the machine is supposed to be filling? .....

meter set to next setting above 240 on the ~ AC volts range 

[Kevin Wood]

So what do we think Gents, 5k?, if its 240v driven sound a bit on the high side to me, works out about 50mA, Not enough to to switch a water solenoid me thinks.

That's 12 watts. OK, it will have considerable inductance so won't draw anything like that much power, but I'd say that's enough.

Does the machine have a hot and cold feed? Can you compare the two solenoids if so?

Kevin

[Nickbat]

It's a Sinometer (cheap Chinese job, I think). Anyway, I have the solenoid here and I've turned the dial to 20k, at which I get a reading of 4.99.

That means the solenoid has an internal resistance of 5K ohms (5000 ohms)

On 200 ohms I get a reading of 1.

That simply indicates the meter is out of range.

Thanks, KW, but is that good or bad?  :-?

That sounds about the right ballpark to me. It's not open circuit (the normal failure mode), at least.

Next question: does it get power when the machine is supposed to be filling?

Kevin

Just checked, Kevin and the answer is No. Looks like I've been barking up the wrong tree. Sorry, guys! 

[zirk]

So what do we think Gents, 5k?, if its 240v driven sound a bit on the high side to me, works out about 50mA, Not enough to to switch a water solenoid me thinks.

That's 12 watts. OK, it will have considerable inductance so won't draw anything like that much power, but I'd say that's enough.

Does the machine have a hot and cold feed? Can you compare the two solenoids if so?

Kevin

Good plan, didn't think of that, or measure the the one that drains it, actually cancel that thats probally going to be a pump? 

[cem_devecioglu]

Nickbat , those kind of equipments sometimes have more than 230V somewhere else.. so stop that.. and call someone professional before you hurt yourself.. :-/

[Andy B]

Nickbat , those kind of equipments sometimes have more than 230V somewhere else.. so stop that.. and call someone professional before you hurt yourself.. :-/

I'd have done that in the first place .... being a lazy bugger.
The last time our washer made funny noises, the drum wouldn't turn. I assumed a siezed bearing in the drum, so bought another washer . As the old washer was being removed, the back was still off from clearing coins out of the pump, I realised that it was a simple bearing in the drive motor that had collapsed!
A new bearing from work fixed the machine for nothing and it's still doing washing duties at my parents house!

[KillerWatt]

So what do we think Gents, 5k?, if its 240v driven sound a bit on the high side to me, works out about 50mA, Not enough to to switch a water solenoid me thinks.

The internal resistance won't be 5K when it's fed from an AC source.

[Nickbat]

Nickbat , those kind of equipments sometimes have more than 230V somewhere else.. so stop that.. and call someone professional before you hurt yourself.. :-/

I'm OK, Cem. The solenoid can easily be pulled clear of the machine and tested without danger. But thanks for the concern, mate! 

[Marks DTM Calib]

So what do we think Gents, 5k?, if its 240v driven sound a bit on the high side to me, works out about 50mA, Not enough to to switch a water solenoid me thinks.

Probably is actually.....

Remember that F=BIL (as a absic formula, not a direct formula for a solenoid though)

Where I is the current
B is magnetic field strength
L is the length of the wire.

And hence a low current through a long wire would as per a solenoid can give a high force

[Nickbat]

OK, so I isolated the machine and went to inspect the front control panel. I found that the panel was only held on to the springloaded arms by one of the existing (pathetic) screws. Despite my long magnet and trawling under the cabinets, I couldn't find the other three, so I dug out some screws to make a temporary repair.

When I took the front panel off, the first thing I noticed was that door closed microswitch was not in its rightful place, so maybe that was causing a problem (or maybe it fell off when I dismantled it). I must admit that I did get some intermittent filling of the machine last night, so maybe that switch was working its way off then. Anyhow, just need to get it all back together/. Probably still won't work, but SWMBO is after a new kitchen in the New Year and told me that if the dishwasher is fubared, we'll I'll  just have to wash up by hand until then. So, this is serious, folks!! 

[Kevin Wood]

Probably still won't work, but SWMBO is after a new kitchen in the New Year and told me that if the dishwasher is fubared, we'll I'll  just have to wash up by hand until then. So, this is serious, folks!! 

Whereas if the kitchen is full of perfectly working appliances she won't need a new one.

Should have seen the look on mrs. KW's face when I fitted a new thermostat to the oven, thus torpedoing her main argument for wanting a new kitchen (and conservatory into which to extend it). 

Kevin

[Nickbat]

Incidentally, I am really embarrassed about not being able to use a multimeter. I'm fine with AC/DC voltage, but resistance, continuity etc. are a mystery. Why didn't they teach me in school? Or was I away that day?   

Anyhow, I did find a really useful PPT presentation on multimeters at:

http://www.wolfmedicalrehab.com/How%20to%20use%20a%20Digital%20Multimeter.ppt

..and the one shown is near-enough exactly the same as mine, so I'll store the file for future reference.   

[Kevin Wood]

Incidentally, I am really embarrassed about not being able to use a multimeter. I'm fine with AC/DC voltage, but resistance, continuity etc. are a mystery. Why didn't they teach me in school? Or was I away that day?   
 

If it was anything like my school they assumed a generic science teacher would be more than adequate to teach electronics (to A level ). I was on the course first year they did it and ended up doing more teaching than the teacher, much to his disgust.

Picked the wrong person to teach electronics, I guess. He was frantically reading up the night before the lesson whereas I had already passed the radio amateur exam and was busy building radios and 8 bit micros after school by then.

Kevin

[Marks DTM Calib]

Probably still won't work, but SWMBO is after a new kitchen in the New Year and told me that if the dishwasher is fubared, we'll I'll  just have to wash up by hand until then. So, this is serious, folks!! 

Whereas if the kitchen is full of perfectly working appliances she won't need a new one.

Should have seen the look on mrs. KW's face when I fitted a new thermostat to the oven, thus torpedoing her main argument for wanting a new kitchen (and conservatory into which to extend it). 

Kevin

Wont be a conservatory.....and will need planning and regs 

[Nickbat]

Well, mainly good news. The dishwasher now works again!

The only downside is that the On/Off push button which has always been a bit temperamental now needs to be held in with a lolly stick. Mind you it is a very good lolly stick and really blends in with the kitchen. 

[Kevin Wood]

Wont be a conservatory.....and will need planning and regs 

That was going to be my next line of defence! 

Kevin

[Marks DTM Calib]

Wont be a conservatory.....and will need planning and regs 

That was going to be my next line of defence! 

Kevin

Well thats a pretty fool proof one.....as you wont be allowed to site a kitchen in a temporary structure (conservatories are classifed as little more than sheds and hence how you get away with putting up such a god awfully insulated thing).

[Kevin Wood]

Well thats a pretty fool proof one.....as you wont be allowed to site a kitchen in a temporary structure (conservatories are classifed as little more than sheds and hence how you get away with putting up such a god awfully insulated thing).

Yep. You're preaching to the converted here. 

kevin