Mt Bob
Minister of Fire
For what it is worth,you can take hobby knife,scratch open the three circuits,for testing with meter, before unsoldering.Then these can be jumped back together with solder,and wire if necessary.
Whitfield died?
- Thread starter Bugs
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Touched up a couple solder areas, and cleaned with acetone and it’s working.
Now I am going to install the inline fuses as Bob suggested and keep my fingers crossed.
I’m still out to lunch on how this can blow the triac before the fuse and wether inline fuses will matter if that is the case.
But it’s better safe than sorry. I’ve learned that lesson ;-/
Now I am going to install the inline fuses as Bob suggested and keep my fingers crossed.
I’m still out to lunch on how this can blow the triac before the fuse and wether inline fuses will matter if that is the case.
But it’s better safe than sorry. I’ve learned that lesson ;-/
Mt Bob
Minister of Fire
I have seen some Harman boards blow the fuse,with no motors hooked up,but does not take out a triac.Probably the transformer shorts after getting hot.
Here is where I’m out to lunch, logic leads me to believe that anything like the fans, motors, etc would blow the fuse if they are drawing to many amps, not blow the auger triac and then the fuse (unless it is simultaneously happening).
I am wondering if as mentioned before something on the board is causing havoc.
I am wondering if as mentioned before something on the board is causing havoc.
Mt Bob
Minister of Fire
um,only when it is acting up,but maybe hook ohm meter to the leads,heat with hair dryer?I have ued hair dryer(well,my heat gun),and contact cleaner(to cool things down) to pinpoint bad/suspect items on a circuit board,but usually are low voltage items.Works really well to check capacitors.Should work in theory for transformer.
Mt Bob
Minister of Fire
On the same note,sometimes england auger motors,when worn out,when get hot,seize and blow fuse,but board is usually ok.
That transformer is very tiny. If its primary was to absorb all the power dissipated when the fuse blows ( 120 x 6 = 720 Watt ) then a meltdown on the primary side would have been the case. On your pic the transformer appears totally undamaged.
When the stove is plugged to the mains, the transformer is instantly active and its secondary is delivering power to the microcontroller through the 5 V voltage regulator. In this stand by state the current flowing through the fuse should be very low. Easy to measure with an ac-amp-meter inserted instead of the fuse.
Measuring the overall current flowing to the stove:
I have tried it, and for a 62 years old like me its a bit awkward to attach the alligator clips on the fuse terminals, since the fuse is pointing downwards. It is necessary to lie down on the floor.
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Unplug stove.
Flip out the fuse.
Bugs, on your advantage there's no igniter plug next to the fuse terminal, so there's more room for the alligator clip, making it easier for you, but take care that the alligator clips don't touch anything except the terminals.
Ready to current measurement:
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With the alligator clips safely attached to the fuse terminals, now plug the stove to the mains. Press no buttons! What amp-reading do you get on the meter? The idling board should only be drawing few milliamps, so it may be necessary to change the meter range. Unplug stove before changing the plugs on the meter if needed.
Now press the start button, but don't press the auger button. What amp-reading do you get, when the start up burst has settled?
The stove will now be running for 30 minutes, until it shuts down due to no fire, so a lot of measurements can be done.
Don't press the auger button this time, since we now are testing if anything else could be drawing too many amps, other than the auger.
This should be fairly easy, except for attaching the probes.
If you don't have an amp-meter ( multimeter ) with well insulated probe wires, don't do this test, but I'm sure you have.
Good luck and take care. Keep posting.
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Mt Bob
Minister of Fire
You are a wealth of info,And I thank you,in case others do not.But,the transformer is the largest thing on the board.Also,the 5v output also has to go through a rectifier,to have 5v dc for the lowvoltage components.I also have soldered bits of wire on pc boards,for testing,as,you are right,small and not much room.What I gave him was a quick everymans test.
And here is a dumb question, if the fuse is blowing as a result of one of the fan motors, would it happen if I keep running the stove without the auger motor. I know I will have to keep turning it back on after 30 min. Could that eliminate that possibility?
Ssyko
Minister of Fire
Im not following your question. (I just made my first cup of coffee) At this point in the testing, If it were me. I would take all the components and ck each of them on the bench for 30 min and monitor the case temps and amp draw. But i wouldnt hook them up to the board without inline fuses. With the fuses in hook ea motor up one at a time and continue monitoring ea for 30 min before you hook up next one.
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When you get to testing the fused motors in the stove, you can bypass the POF low-limit switch TEMPORARILY and run the motors as long as you want.
I guess what I’m saying is I started the stove to see if the board was working (no fire) went out to my shack to tinker on something else forgot to shut down stove, when I came back in it shut off from limiter switch, hmmm what the hell I started again, I’ve run it for several hrs now (without auger) and it’s still going. No blown fuse.
Ssyko
Minister of Fire
Sweeeet! Everything is working just auger out of the loop. When is the fused auger test?
Soon... I still have to put the fuse in line (5 min job with my new mad soldering skills ;-) )
It has always been my thought that the problem is in the board itself, it only makes sense to me with my limited electronics knowledge.
Ssyko
Minister of Fire
My thoughts on the auger is it draws to many amps, but that wouldn’t blow your triac only the fuse. So im leaning towards a temperature activated short in the transformer low voltage somehow getting a line voltage spike.
If this is the case, then we need to ask Bugs this question: While having the stove running for several hours, did you check if the blowers reacted to the different settings on the control panel, or were they running full speed no matter what setting? The speed of the convection blower is the easiest to monitor by ear, as it is quite loud and blows directly out in the room.
Ssyko
Minister of Fire
Keeping our fingers crossed.
But you know what, all that dust and dirt on the terminal strip? If it gets humid, wouldn't that enable a lot of electrons to stroll around where they are not supposed to? Just a thought.
This is a real story:
Some people i know had a serious short circuit in a wall outlet. It was my job to find out why. After some testing it turned out that their male cat had made scent markings ( peed several times ) on this outlet.
With my ohmmeter I took a rough reading of the conductivity of the layers on the outlet: Even when the probe pins were 2 cm apart, the resistance was 0 Ohm!
So beware, dust, dirt etc.( especially if a bit salty ) combined with humidty can be highly conductive.
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Ssyko
Minister of Fire
Yes its a good possibility. Why did they not run a 1 piece wire harness. Just the extra connections could cause problems.
3 hrs and still running. I guess I’ll throw my 2 cents in, I think it was a simple issue that was not overlooked but perhaps not considered enough by me. The only thing that has changed besides 5 triacs and an inline fuse is the rubber insulation between the terminal and fresh air inlet, no matter where I put the rubber bumper the terminal hits.I think it was touching close enough that it would dead short, On heavy torque. Still wouldn’t explain triac first or simultaneous with fuse.
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