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Heating element slowly died 2 months after broil went down. Clock/stovetop ok

Heating element slowly died 2 months after broil went down. Clock/stovetop ok

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  #1  
Old 06-21-14, 06:36 PM
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Heating element slowly died 2 months after broil went down. Clock/stovetop ok

Hi there! I'm so glad to join the forum! A little help would be appreciated. Here's my problem :

Two months ago, I realized the broil element wasn't heating anymore. I heard a "click" sound when I pressed the "broil" button, but nothing else happened. I've managed to cook with the lower (heating) element since then. One day last week, I noticed it was unusually long to reach the set temperature. In fact, it was a matter of minutes before the element stopped working completely. As for the broil, I can still hear the "click" sound, but all that is still working is the stove top and the clock/timer.

I removed the back panels and found no signs of burnt/worn parts. The home breakers are still ON.

In case it helps, the range was bought in Canada and was seldom used at high temperatures (450 F) until a few months ago, but I only use it on an occasional basis. Surprisingly though, I haven't changed the way I use the broil element and it is what failed in the first place.

I don't own a multi-meter to test the elements, and I wish I could get more info before having to purchase one, since I doubt I will use that device often after the oven is repaired. BTW, how much should I spend for a decent one? 50$?

Thank you!

Kev
 
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  #2  
Old 06-21-14, 08:06 PM
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Welcome to the forums.

How do you use the bake element as a broil element ?
The broiler element is mounted up top and the bake element heats from below.

Running an electric stove at 450f will decrease the life of a heating element. If you don't want to test the element.... just pick up and install a new one.

Otherwise you can buy an inexpensive meter from the Shack or even the Depot.
Gardner Bender 14-Range Analog Meter-GMT-318 at The Depot
 
  #3  
Old 06-21-14, 10:14 PM
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Thanks PJmax for the quick reply. Sorry, my last post was unclear. I don't use the lower element as a broil element. It's just that, as I mostly bake food with the lower element, the oven was still usable even without the broiler.

Anyway, if a 25$ tester will do the job, I might buy one and test the elements. But it would be odd for the two elements to break 2 months apart. It makes sense that heating at 450F wears the element, but how about the broiler element that was used as usual? The range is only 6-7 years old, and I broil for 10-15 minutes each month.
 
  #4  
Old 06-21-14, 10:59 PM
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It is hard to determine when an element is going to fail. I've seen them last only two years and well over fifteen years.

At this point we aren't even sure you have an element problem but by checking the continuty of the element you'll know which way to turn.

One important thing is to turn power off to the range before even touching the element. In many ovens.... one side of the element is always live and you wouldn't want that end to touch the metal frame.
 
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Old 06-28-14, 09:39 PM
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Hi PJmax,

I unplugged the elements and tested them with a multimeter. Baking element : 21 ohms, no sound in continuity mode. Broil : 19.7 ohms, low sound similar to purring cat (not like a high-pitch noise when you touch the red probe with the black one).

Now I believe I have a few options :

1. With the elements back in place and the oven plugged in the outlet and running, check the voltage by placing the probes where the element is connected to the wires. How safe is that? If it doesn't read 240V,then its the oven control board.

2. Found on the internet : "Check if the voltage is present to the Electronic Oven Control (EOC) board on the 15 pin connector. The (EOC) should have 120vac when measured with a volt meter across pin 4 and pin 5. Pin 4 will have a Black wire and pin 5 will be a White wire. These two wires provide the voltage to power up the Electronic Oven Control board. If voltage is present, replace the Electronic Oven Control. If there is no voltage, you will need to trace both wires back from the connector to find where the break or loose connection is." Where exactly should I place the black and red probes? (see attached image below)

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3. A few steps on how to test the control board (from appliance411.ca) :
"Remove electrical power.
Go to the back of the control and disconnect the multi-pin plug.
Check the wiring diagram to determine which two pins in the plug (not on the EOC) are connected to the oven sensor.
With an Ohmmeter check the resistance between the two pins in the plug that are connected to the of sensor. At room temperature:
If the meter reads below 900 Ohms or above 1200 Ohms, remove the sensor from the oven an check it for resistance. [...]"
--- Please someone help me understand that. I'm posting pictures of the whole back panel in case it helps :

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4. Test the thermal fuse, but I can't find it on my oven.

Looking forward to your next post. Thanks for your help!

Kev
 
  #6  
Old 06-28-14, 10:26 PM
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Hey Kevin.....

Read the following thread as it's almost the exact same problem as yours.

http://www.doityourself.com/forum/el...d-working.html


Your elements check out ok. The tone from the meter gets louder as you approach 0 ohms.
What you measured is acceptable.
 
  #7  
Old 06-29-14, 08:17 PM
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Hi PJmax,

I looked at the thread. You mentioned three possibilities : 1) losing the 240vac to the unit, 2) the control board is defective, 3) high heat safety stats. I don't have high heat fuses on my oven, and I checked the 4-prong outlet with a multimeter and there was 240 volts. But before we conclude that the control board is defective, could it be that the power is lost (broken wire?) somewhere between the outlet and the control board?

My understanding is that power goes to the control board through the black and red wires, goes to the oven/broil elements through the blue and yellow wires, re-enters the board through the orange, and leaves again through the white. I'd like to test voltage at the control board to see if current goes up there. I'm not sure where to place the multimeter probes. Can you give me some advice by looking at the picture below? If I need to touch the white wire, I wonder how I'll be able to do it since that wire is located inside one of those narrow square holes. Or can I unplug that white plastic multi-pin plug?

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Also in the thread you advised me to read, Steve posted a picture of his control board. I'd like to do that too, but I don't know how to access the "green" side of it. Am I supposed to push the 12 or so pins to free the circuit board from the black case? They're hard to push and I don't want to break anything.

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By the way, I tested the temperature sensor. 1089 ohms on one side is as expected, but I'm not sure about the 2610 ohms between the other two wires. Could that be a problem?

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I'd also like to check voltage at the main terminal block. I should read ~120 V between the red and white wires, for instance, but is it okay to place the probes as shown on this picture (i.e. under the terminal block)? Since power will be on, I afraid of touching the wrong place.

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Many thanks for your help so far.

Kevin
 
  #8  
Old 06-29-14, 11:08 PM
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In the other thread he emailed me all the large pictures of the boards and the schematic that is posted in every appliance. I analyzed them and told him what to do.

Those little clips are what hold the board in place. You'll need a small screwdriver to carefully release them.

You need to check for 240vac between the red and black terminals on the connection block. Just be careful the probes don't slide off the terminal and short the terminal to ground.

The measurement of 1089 ohms on the sensor is fine. The other measurement is the board and we don't need to check that.
 
  #9  
Old 06-30-14, 05:43 PM
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Good news, PJmax (or bad news)!

I had nothing to lose, so I popped out the circuit board and I saw two burnt spots. The darkest one is in the middle. You'll find the other one on its right.

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I can't compare with Steve's pictures because of resolution. I wonder if I could bring it to an electronics specialist to have it re-soldered. What do you think?

The other green board looks fine:
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Thanks a lot! This forum is a wealth of information!

Kev
 
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Old 06-30-14, 06:25 PM
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This is good news. Would you rather spend $150-200 on a new board ?

The two connections that are blackened should be cleaned with isopropyl alcohol and an old toothbrush. All the solder joints in the heavy foil area should be resoldered.

You can pickup an inexpensive 40 watt soldering iron at the Shack or a place like the Depot.
Weller 40-Watt LED Soldering Iron Kit-SP40NKUS at The Home Depot
Wall Lenk 40W Pencil Style Electric Solder Iron : Soldering Irons | RadioShack.com

The foils are heavy enough where you can't burn or hurt them with the soldering iron. Be sure to only use ROSIN core solder.

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  #11  
Old 07-05-14, 11:58 AM
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Resolved

Hi PJmax,

My girlfriend asked a colleague to take a look at it. He said there were cold solder joints (?), meaning some kind of bad quality joints. I'm not familiar with soldering terminology, but I think the board was originally made under a cheap process. He resoldered parts of the board, possibly making it stronger than it was before. I don't know if he worked on all the areas that you mentioned, since I haven't seen the final result, and I'm too lazy to unscrew and re-open everything.

The outcome :
- Bake and broil elements now working
- No money spent, except for the multimeter
- Complete satisfaction
- New knowledge, thanks to your many pieces of advice

Thank you so much!

Take care

Kev
 
  #12  
Old 07-05-14, 12:28 PM
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You're very welcome.

Most of today's PC boards are machine soldered in a wave solder machine. The machine is set up to solder almost 90% of the components on that board properly. The terminal and relay connections are usually hand soldered after the board has been wave soldered so that they are completely soldered. However, in the production process, that hand soldering phase gets bypassed and allows a board to leave with questionable(cold) solder connections right from the manufacturer.

In your case the ones I double circled had completely failed. Those were cold soldered. The other ones I singly circled can be future failures which is why I recommended soldering all of them.
 
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Old 07-05-14, 12:48 PM
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And as I remember, cold solder joints can have a higher resistance, thus they heat up. As they heat and cool the joint can eventually crack when that happens you get arcing and oxidation and eventually no contact at all. Been a while since my soldering school days though.
 
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Old 09-26-14, 07:28 PM
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I fixed this problem in my range...

I just saw this thread. I wish I had taken a photo, but I fixed it by soldering a bare piece of 14AWG solid copper wire from the offending solder joint to the other joints. I believe the problem is a design issue-- I don't think those solder joints (or the PCB traces) were really meant to handle 10-15 amps of current. The copper wire I added (it was a pain to get the wire bent just right and held for the soldering) gives a larger surface area for the current to pass through and so it doesn't get hot and melt the solder. I ended up having to go in multiple times to add copper across the traces, I should've done them all at the beginning. But it is fixed now and is no longer a problem. Mine was a Maytag gemini. I'm not sure if this makes sense, I don't want to go back in a take a picture...
 
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Old 09-26-14, 07:58 PM
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I've received a ton of PM's from members whom have also fixed their own boards.

In the following picture it's very obvious that the PC board foil is a design issue on the left connection. How could that small piece of board be expected to carry 3500 watts and better.

You could have used #18 wire also. It's the combined effort of the wire and the solder. I have spools of #16, #18, #20 specifically for this purpose.
 
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