I have a Kitchen Power vent (model: JVB67) and when I touched a wire to the body, I saw a spark fly and it no longer worked. The wire was to the raise/lower button which is just completing a circuit like a simple doorbell does.

I removed the cover and found a resistor burnt out on the board (model: WB27X10704) and I'd like to replace it, but I have never done a resistor before since I'm a noob. I just want to be sure I purchase the correct one. I have soldered some stuff onto boards, but I'm not worried about the soldering, just getting the correct resistor.

Viewing these photos, can someone verify that the one burnt out in my 1st photo in what I think it is?
Orange/Orange/Brown Gold? ...330 Ohms, +-5%?

The other photos are of the board WB27X10704 from online retailers and ebayers. So the 1st photo is my board, and the rest are other people's boards to identify the colors of the resistor.

Thanks in advance for anyone who helps me identify the resistor!

 

330Ω 1/4 watt

 

There's something about that photo that says "capacitive dropper".

 

Thank you Max!
Ian: What is "capacitive dropper?" Thank you.

 

Ian: What is "capacitive dropper?" Thank you.

It's a circuit to generate a low-voltage supply (say 5V to 15V) at low current, but not isolated from the mains, in order to run some logic or control circuitry. it consists of a Class-X capacitor (one on your board labelled 224), a high voltage diode (the black one), a zener diode (the glass one), an electrolytic capacitor (the black sleeved cylinder) and, usually but not always, a power resistor (green, labelled "3W")

 

My guess here is that your fried resistor is merely a symptom. Resistors burn up sue to excessive current. Replace the burned up resistor and you will see another burned up resistor. The trick is finding the root cause which caused the symptom.

Ron

 

Reloadron/Ron: I did explain in the 1st post that I touched a live wire to the grounded body which caused a spark and the unit stopped working. Are you suggesting there's more to it than that?

 

Are you suggesting there's more to it than that?

It's likely that the spark you saw damaged a different component and that damage caused the resistor to burn out.

 

It's likely that the spark you saw damaged a different component and that damage caused the resistor to burn out.

That was my thinking. On the bright side resistors are cheap so replacing it is no big deal, however, if the replacement cooks there is more looking to do.

Ron

 

Ok guys, thank you very much for your expertise. My 100 count 330 ohm resistors for $5 will be here on Wednesday (3 days from now), so I'll replace it on that day and come back to post if it worked.

This unit is so obsolete that the control board cannot be found in stock anywhere online. So if I cannot fix it with a 5 cent resistor, I'll have to pay $950 for a new telescopic exhaust vent for the kitchen! Ugh.

 

Well there's not many components on the board so it shouldn't be hard to fix. Maybe start with the thyristor and opto, only a few dollars worth of components.

 

UPDATE: I replaced the resistor and it did not work, just like you all suggested. Could you please advise me on what to replace next? I looked up a thyristor but cannot find the "T435 400T, but I can find a T435 600T (which is what's used in the photo above on an ebay sale of the board.

PROBLEM: I spent 2.5 hours trying to solder the resistor onto the board. Yes, 2.5. My solder will not melt on the tip of the iron; it'll melt on the shaft where it is hotter, though. I tightened the screw, but it didn't help. I do know not to melt solder with the iron itself, and to heat the medium, not the solder (I solder pipes and it's the same thing) and to keep the tip clean. I also have tiny diameter solder with flux in it, so it should melt easily. My iron is a cheap pencil style which is 30 watts. It seems to stay cold for many minutes, then suddenly it'll melt solder for a short second or two, then that's it, for a LONG time. I totally destroyed the hole in the board trying to solder and get no continuity inside the hole. I ended up scratching out the board and exposed the copper and have the tiniest adhesion with solder. It's a mess, but I do test for continuity at the next hole successfully. I have a massive 240 watt soldering GUN, should I try that with my next attempt? I have watched many videos and it's easy but nothing works with my iron. It cannot get hot enough to heat the resistor strand enough to melt solder (I'm thinking).

Thank you!!


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By the way, the new resistor did not burn out.

 

Yay, let's hope the new resistor never burns up. Especially considering how soldering 101 went. A 30 watt pencil should have been plenty. How thick was the solder? Was it lead free solder? I still like the old 60/40 tin lead solder and you should have no trouble melting for example 0.5 mm diameter or a little thicker. Anyway glad it seems to be working but have to wonder why the old one cooked? Oh well.

Ron

 

Reloadron: Thanks for the reply. My solder is 1mm. The spool has no label and I cannot find it in my Amazon purchases, so I don't know what it's made of.
(1) Should I get thinner solder;
(2) Should I get a 60/40 mix?
Thank you.

 

I do need advice on what component I should replace next since the new resistor didn't fix it.
I ordered .5mm solder.
Thank you!

 

I am still hoping to get any advice on what to replace next. Thank you!

 

SUCCESS!!
I replaced the Optocoupler/opto-isolator and it worked!

 

Well good going and glad it is working.

Yes. 0.5mm of 60/40 should do you fine for small work.

Ron