Replacing Thermal fuse

Have you looked at the dishwasher electrical circuit schematic and attempted to identify the damaged part?

If not perhaps you should before making further speculations.

If you don't feel qualified to correctly identify the damaged part leave the repair to a qualified repair person.

If there was a schematic around then I wouldn't have to speculate.

Like you? Just wondering if that is a rhetorical question? Because obviously if I didn't feel qualified I wouldn't have asked such a thing.

I really don't like your condescending attitude... are you a repair man looking for business? I also don't think you should assume everyone is a total dumbass... it only makes you look arrogant.

How much experience do you have in electronics?

I really didn't read Bo's comments the way you did. This is a basic group, people are over their head a lot here. I recognize your name so I know that you know something about the subject but his answer didn't sound condescending to me. You could say "Mind your own business Tom", and I will accept it.

Regards, Tom

A thermal fuse is not a fuse in the conventional sense. It has a *temperature rating* not Amps.

Possible the wrire was crimped to it, the crimp became loose and hot and blew the fuse.

What does it look like ?

Graham

One side is completely charred and disintegrated the other looks ok. (it's about the size of a penny but 10 times thicker.

Well, maybe... but when one automatically assumes the other guys a moron then I think that is condescending. Specially when no other help is offered but "your to stupid to do it yourself so go pay someone else 1000 times what it's worth".

Something like

"> If you don't feel qualified to correctly identify the damaged part

kinda proves it for me. Seriously... why would I ask such questions if I didn't feel qualified? (being qualified is a totally different story)

The reason I asked here is because I've never worked wtih thermal fuses and only know how they work in theory(a bi metal that seperates as it gets hotter). So I do not know how they are used in practice and how to properly rate them.

he also says

Which assumes I'm not competent enough to look for the schematic... in fact I searched google for about 30 mins but couldn't find anything on it.

(incidently I took off hte front cover and find a wiring diagram along with cycle information... not helpful though)

In any case it doesn't matter. I got some fuses and a breaker in there(for a master switch when I need to work on it) and it runs but not sure about the heater coil.

It seems to always run at about 10V and sometimes jumps up to about 16V. The nichrome measured about 14 ohms so thats only ~200W and the manual says it's a 900W heater. Not sure if it slowly ramps up or maybe the heater coil is messed up(not sure how since it's just a wire).

But being that it reads 10V even when off is a bit suspicous.

In any case I'm looking at the control circuits and seeing if I can find out what else got messed up.

(it would have been one thing for Bo to answer the way he did but also answer my questions... totally different when he assumes(or doesn't even know the answer himself) the other guy is ignorant on the other end)

Actually you could be completely right. The screew that was holding it down was all rusted and the wire could have been making very little contact causing it to heat up... but not sure how it would have basically destoryed that one side.

In any case it's besides the point as I need to figure out how to fix it. Right now I'm using a circuit breaker as a master power switch(since it doesn't have one) and a fuse holder + 10A fuse on the heater coil(not that I like to replace fuses but for now it will work).

For some reason even when the washer is off the heater coil is getting 10V or so(Although I'm measuring directly without the heater coil so it might drop down with a load) and it goes up to about 16V. I do not know if it will eventually go up to the 100V or os it needs to or what.

Although the manual says it's a 900W heater and I measured 14 ohms across the element so that doesn't make too much sense. 14*120 = 1680W which is almost twice as much ;/

guess I better remeasure everything ;)

hmm, if I could do simple electronics it would be ok ;/

120^2/14 = 1000W

which I guess is ok.

looks like relay controlling it is bad though

Any chance of a pic ? What terminals did it use ? Not 1/4" Fastons by any chance ?

Graham

If it was a thermal switch there would be no specific reason for that unless the switch was 'chattering' and eroding the relay contacts.

Graham

Well, maybe you are right.

I don't know but if he can make such assumptions then I believe I have the same right ;)

Not sure. I tore up the relays(covers couldn't be poped off) and I think I screwed up the darlingtons that drive them... now the heater coil relay is always on but it does give 120V on the coil(which I don't think it did the first time I checked it)

In any case I have some drivers coming so hopefully I can replace them and it will work.

The relays require 30V and I think I got the polarity wrong and it fried the driver ;/ Now 2 relays seem to be stuck on.

Was trying to find out another solution to replace the darlington array(ULN2803A) to check it but can't think of any way ;/ I do have some discrete darlington's that would definitely do the job but would be a mess wire them all up(+ resistors and diodes) ;/

I guess I'll have to wash dishes by hand until the chips arrive ;/

I'll try to get a pic someone. I've never seen anything like it. It uses force from a washer to hold the fuse and connectors in.

Think of a very thick penny with a small square carved out on the top and side and same on other side. It has a nipple that the wire connector sat in and a rectanular piece that held that in. The washer and screw held everything in place.

Never seen one like that before.

I would suggest replacing with something like this.

?N=500005+1002028+278291&Ntk=gensearch_001&Ntt=thermal+switch&Ntx=&_requestid=576713

Graham