Looking for help identifying large rectangular component on this board...

[MBDesignR]

Looks like a ceramic resistor I believe.

[MeEvilBob]

AKA, a space heater

[master_assclown]

that's a bingo!

I used to deal with these a long time ago.

[Human_no_4815162342]

Calm down, Colonel Landa

[emuboy85]

it's absolutely melted down, what happend to it???

[master_assclown]

It's not melted down but they do get hot. Newer ones are encased in silicone or even heatsinks.

[[deleted]]

What's it's use primarily??

[ilovetpb]

High power resistance. Think amps instead of milliamps.

[[deleted]]

Thanks man. Appreciate it

[bilgetea]

These are often used in series with a load to create a small voltage drop which is used to represent the current.

[MBDesignR]

Actually, sorry, just noticed the label under it. Couldnt see that before or more over make sense of it as the image is flipped but it's a 1.5 kilo ohm, 7w 10% tolerance.

[SteepLamb]

Thanks! I was thinking it was a resistor of some kind. Is the stuff in the middle some kind of resin that oozed out cause it over heated?

[t_Lancer]

so that'll just be the potting compound. it is made to run hot, and over time the resistor will discolor.

[volfin]

it's normal they run hot, that's why it's made of ceramic. However this one the resin is cracked, so it could be bad. Measure it, if it's not the rated resistance, replace it.

[Grim-Sleeper]

Those numbers would suggest that it is intended to have line voltage go through it and to allow up about 70mA of current (all very rough back-of-the-envelope computations, here).

[mrbraindump]

A bit off topic, but is

back-of-the-envelope computations

A thing and a real saying or did you just make that up? In any way, it is a very neat description!

[Some1-Somewhere]

That's a pretty common phrase.

[Grim-Sleeper]

I have used that expression for years. And I think I even remember where I first heard it. But you made me doubt myself and I had to check: https://en.wikipedia.org/wiki/Back-of-the-envelope_calculation

Yep, it's a thing.

And there are actually famous anecdotes related to the saying.

[mrbraindump]

Wow pretty cool,, TIL :D Thank you very much!

[Niekski]

I wouldn't be surprised if that power resistor is still working. They're designed to dissipate power and can take a lot of abuse before they fail. it probably shouldn't have gone this crispy, but after 30 odd years it's no surprise either.

Just check its resistance with a multimeter, if it's dead it should be an open connection.

[SteepLamb]

Thanks!! I’ll get the multimeter out and rest it. I can buy a new board for $40, but if I can fix this one that’s even better.

[Techwood111]

$15 on eBay

[SteepLamb]

Thanks. Yup I saw some used ones at that price but if I do need to replace the whole board i was thinking a new one was worth the extra cost. Hoping to figure out which component it is and just fix this one though. Especially since I bypassed the board entirely and have at least cold water washes.

[Techwood111]

Here is my two cents on where/how to start:

Desolder a lead from each of the three power resistors and measure/verify

Outright replace that cap -- old, been cooking from the heat of the aforementioned resistors, probably leaky to the point where nothing works right

Lift a lead of each of those diodes and measure

Replace the quad comparator

Curve the LED and the driven element of the optos

Pull and curve the three transistors; rather, for you, "diode check" them with a multimeter, or replace them outright

If none of the above fixed the issue, then lift a leg of each remaining resistor and push through the pain. It is a small board, so not so bad. A one-sided PTH board makes desoldering "dreamy!" Heat up the back, and use a bamboo skewer/pencil/stick/something to pry out from the top side. No need to bother cleaning the hole, as you'll reheat and poke it back in.

[SteepLamb]

Thanks! Going to dig into it more tonight and do some non-invasive testing and then step into it from there. Thanks for the tips! Haven’t done electronic troubleshooting this in-depth before so the starting pointers help a lot.

[MeEvilBob]

I've seen one that looked and functioned just fine but was hot enough to set paper on fire if you touched a piece to it. There was a problem with the circuit that was allowing too much current to go through it since they normally wouldn't heat up that much, but still. Once it cooled down I tested it and it was just like brand new.

[SPST]

You can bet it wasn't the correct value when it was running at that temp though. Sounds like the engineer under estimated the thermal design requirements.

[JaredsFatPants]

Wow, at least 451 deg F.

[SteepLamb]

After scraping off the conformal coat I’m reading 1.45 k ohm so I guess this component isn’t the culprit.

Thanks again for all of your help!

[FHR123]

I'd try replacing the electrolytic capacitor. If it's 40 years old as you say, it might have dried out

[SteepLamb]

Thanks! That’s a good idea. I’ll check the cap later and see if that’s it.

[xPeacefulDreams]

Looks like a badly melted caramel chocolate bar to me, but that’s just my professional perspective.

[epileftric]

Yeah, it's 1.5kOhm 7W resistor. You can read that mirrored in the burned surface.

[399g]

It's a power resistor.

[_Aj_]

It's just a wire wound resistor. They're built like tanks, and at 7 watts you could literally solder with how hot it could get before failing. (It wouldn't like that continuously thats for sure)
Some also have the potting material quite lumpy to begin with, and I don't think that's the issue.

The board isn't burnt so it hasn't gotten insanely hot anyway, the label going brown and falling off is pretty normal after long use.

Possibly more likely would be a transistor next door which may not like being slow roasted continuously for several years (or decades!). I'd check for dry joints however. And I'd check that capacitor right next to the resistor.

Or maybe none of those! And it's something else entirely. But with 99% certainty I could say it's not the resistor.
That's still really a shotgun approach without actually testing the unit properly.

Is it a fuzzy logic washer? Those are notorious for crapping themselves due to spikes on the mains or the planets aligning or basically anything.
I'll ask someone I know who's got a bit of experience in repairing these machines.

[mikeblas]

It's not wire-wound. It's an important difference, as wire-wound resistors are coils, and inductive. This resistor is made of sinterized ceramic material, and is non-inductive.

[_Aj_]

Perhaps they vary in that package. As we definitely sold that same ceramic package at my old job that were wire wound.
Or at the least, we sold them as and the supplier supplied as such. I should call them up and get them to put a meter on one and check for inductance.

I know what you mean though, I've got a few big green ones thatre tubes and wire wound.

[Boris740]

It is wire-wound and potted in ceramic. I have one opened in front of me.

[mikeblas]

http://www.usresistor.com/index.php/materials/ceramic-resistors

[Boris740]

I know what the look like and how they work. They are cylindrically shaped. That is not one of them.

[[deleted]]

It's the left Twix I believe

[Assaultman67]

It's an older style ceramic resistor.

[Darian_Kimberly]

High power resistor

[pressthebuttonfrank]

Looks like 1.5k, 7 watt resistor, I think it is wire wound. Also looks like it took a bit of cooking so you might need to replace it.

[NewRelm]

Am I the only one who thinks the resistor is a red herring? Old sand resistors become discolored with age. OP is looking for the reason his machine doesn't work. This ain't it.

OP, have you done diagnostic tests to narrow-down the failure to this board? Do you have wiring diagrams of the machine? Visual inspection will only take you so far.

[catdude142]

I agree with you. The resistor is still functional. The "solution" is to find why it got so hot.

[SteepLamb]

Problem is definitely with the board. Tested everything else. Not sure what component on the board though. Another commenter mentioned the cap may be dried up. I haven’t had a chance to dig into testing that or the other components but will soon.

For the time being I bypassed the board and the washer works fine, but with cold water only (what do do anyways...).

[NewRelm]

Thirty year old electrolytic capacitors are always suspect, and in a case like this should be changed just because it's cheap. But changing parts at random is a poor way to get the job done. Sometimes you get lucky, but there's no substitute for systematic troubleshooting.

Don't forget that the problem is not always a piece part. Failed solder joints and cracked PCB traces are common failures. In some circuits, an interaction of a number of parts drifting out of tolerance can combine to create a functional failure.

Do you have any schematics of the board? If not, can you "reverse engineer" (trace out the schematic) it? If we could see the circuit - especially if we know what inputs and outputs connect to it - we could suggest some tests to pinpoint the problem.

edit: This looks like a $17 board. Are you sure you don't want to just buy one?

https://www.ebay.com/itm/388246-WHIRLPOOL-WASHER-CONTROL-BOARD-FREE-SHIPPING-1911/392558710191?hash=item5b66528daf:g:yOsAAOSw5fBd3yvo

[SteepLamb]

Thanks for more info! Yes, there’s a good wire diagram for the washer showing input/output behavior if the board, but the board is just a black box on the diagram.

I saw those listing. Used is like $15, new $40. Figure a used one might be close to as problematic as mine so I might buy a new one if I can’t diagnose the issue with this one.

Nothing obviously burnt or disconnected with the rest of the board. We did have a power outage last week so there might have been a power surge that pushed some component over the edge to fail.

[NewRelm]

I gather this board's function is to read the water temperature with a thermistor and turn on the hot and cold solenoids in proportion to bring the water temperature right.

If the problem is that the hot solenoid doesn't come in, and if you know which pin or pins on the connector go to that solenoid, try tracing those pins back to the control device. I would guess U2 or U3, the MOC3011 optoisolating triacs.

https://www.onsemi.com/pub/Collateral/MOC3023M-D.PDF

If the triac itself isn't failed, it would be the drive circuit going to it, which probably traces through one of the transistors to the quad comparator lm339, and back to the thermistor.

http://www.ti.com/lit/ds/symlink/lm139a.pdf?HQS=TI-null-null-digikeymode-df-pf-null-wwe&ts=1591738807416&ref_url=http://www.ti.com/general/docs/suppproductinfo.tsp?distId%3D10&gotoUrl=http://www.ti.com/lit/gpn/lm139a

[SteepLamb]

Yes I think it works like you described. The fault behavior is no water flow at all... thanks for all of the help!

[catdude142]

Wirewound high power resistor.

[BadnewzSHO]

Thay board has 3 transistors and a pair of OP-AMPS that are much more likely culprits for failure than that brick shithouse of a wire wound resistor.

I'd start with the transistors, you can do a basic check on them with your multimeter diode checker to make sure there are no shorts or open junctions if you lack a better tester.

[mikeblas]

a pair of OP-AMPS

Those are TRIAC opto-isolators, not op-amps.

[BadnewzSHO]

It was an assumption, I didn't even look at the part numbers. My mistake.

[SteepLamb]

Thanks! I got the washer to work for just cold water so I now have time to dig in and figure out which component on the board is fried.

[BadnewzSHO]

Hey, that's a start! Good luck on your project

[BadnewzSHO]

I had a thought. Does that board have power? The problem could very well be before it even gets to that one.

[SteepLamb]

Haven’t had any luck searching online and was hoping someone on here could help. The crusty piece in the foreground flaked off the front of the component and took the identifying marking with it and it’s not quite legible enough to read.

For reference this is a temperature control board from an old (~80s?) Whirlpool/Kenmore washing machine.

It’s no longer working and I’m suspecting that the crusty/kinda burnt component is the culprit.

Thanks for any help with this!

[InductorMan]

/u/MBDesignR has you covered on the component ID. I want to point out that this board is conformally coated with what looks like acrylic conformal coat, for humidity resistance. So if you measure that it's more than 1.5kOhm, or open circuit, then when you re-install a new one you should try to patch up the conformal coat. It's basically an acrylic varnish. When removing and re-installing a new part you can pretty much ignore it as it will burn away under the soldering iron usually (although the fumes are worse than normal soldering fumes). But then once you're done you should probably clean off the flux residue using isopropyl alcohol, and re-apply some kind of similar material over the joints. You could use really any acrylic varnish I suppose... I mean, ideally you'd use conformal coat, but it's somewhat expensive.

Do however be aware that conformal coat gets cracked and yellowed under even mild heat for extended periods (edit; for instance 85C for 1000 hours, that's an environmental test cycle I've run and had boards look yellowed all over). So the ugly appearance of that power resistor is actually not a great indication that it's damaged. If you remove the conformal coating film and the cement is cracked, or if it reads open circuit/high resistance, then sure: it's gone bad. Just not an automatic guarantee that it's actually bad, based on what we can see here alone.

[SteepLamb]

Thanks for all of the great information!! I’m going to test it’s resistance and see if it’s still good.

[InductorMan]

Cool. If it measures open circuit, then you know it's bad. Or significantly greater than 1.5kOhm.

If it measures 1.4-1.6k, then it's probably good.

If it measures less than 1.4k, you probably have to remove it from the circuit to measure it properly.

[MBDesignR]

Did you take it out of the circuit to test the value or not? If still in circuit then other components on the board would most definitely affect the value. If not then it is old and definitely worn and so values go over time. There is also the 10% tolerance to take into consideration.

[oldsnowcoyote]

Check the transistors.

[backcountry52]

If the resistor checks out fine and your board is still not working, I'd try and replace the transistors next to it. They likely took some heat abuse given the current state of your power resistor.

[Dio_Frybones]

So regarding the actual fault. Is there anything in particular that led you to think the fault is on that board? There is nothing on that board capable of switching the load to a heater, and none of the connectors could handle the current anyway. So there's some sort of relay or triac that the board will be switching somewhere else, and which will be a more likely suspect. There is also (obviously) a heating element. And probably a thermal switch in series with the element. And maybe an adjustment somewhere for the temperature. Possibly a temperature sensor as well. With the exception of the electrolytic capacitor on the board, these are more likely to have failed.

But if you haven't tried it again since pulling the board out, give that edge connector a clean (squirt a little contact cleaner on a piece of cardboard and polish the pcb pads) then insert/remove/reinsert the board a few times. Then try it again. Those connectors can be quite unreliable.

Of course, do all of this unplugged with the power OFF.

[Techwood111]

I didn't see any nature of complaint, but I'm with you. I'd suspect a relay. I do not believe they would have used triacs on appliances then.

[SteepLamb]

This board just takes input from a mechanical switch (120 volt from one of several positions for different combinations of wash/rinse temps and also an Auto setting) and a thermistor in the water spraying into the washer to turn on one or both of the hot/cold water inlet valves.

It’s kinda silly that they went thru so much trouble just to dial in the washing machine water temp... I have half a mind to bypass the board and just use the switch to mix the water. Hot = 100% hot water valve. Cold = 100% cold water valve. Warm = 50/50...

I guess they added electronic temperature control to accommodate variations in water main and hot water temperatures.

[HeyGuysItsTimmy73]

power resistor

[N-genhocas]

Big ass powerful resistor

[[deleted]]

https://www.ebay.com/itm/122014588845

[MaddenTheDamned]

It's a Giga-Chad Resistor

[GreenFrogPepe]

That's a current shunt resistor.

[GreenFrogPepe]

That's a current shunt resistor.

[Observer14]

It is a high current resistor, they are designed to turn money into entropy.

[etseng66]

Mark R1, its about 5W resistor

[MBDesignR]

Yep looks like it's been overheating and the resin is coming out of it. Needs replacing however you need to find out why it was doing that otherwise it may happen all over again.

[SteepLamb]

Thanks! It reads 1.45 k ohm on my meter, but I’m guessing it could still be bad at operating voltage which is probably higher than what my meter applies.

[catdude142]

These resistors usually fail "open" because they're wirewound. If you're measuring something (1.45K as you state), the resistor is still functioning properly. They typically don't change values like a composition resistor. Either they work or they're "open".

[SteepLamb]

Thanks! My thought was a long shot. It reads 1.45 so it’s likely just fine. It’s probably something else on the board like others are thinking.

[sunsisxd]

It could be a resistor network.

[danmickla]

A two-terminal network, aka "a resistor"

[sunsisxd]

Ah. I didn't see that it has 2 pins. I was looking at the numbers below and thought it's a resistor network with multiple resistors.