Hello all,
I am attempting to repair a control board for a gas oven. The initial fault occurred after a lightning storm, the digital read out and all oven controls ceased to work. Upon inspection I found a resistor on the line side to be open. I replaced it with a 1/4watt as that is all I had at the time. I applied power to the board while on the bench and it worked (display lit and buttons functioned), however when my dad plugged it all back in it "sparked, crackled and shut off". I then purchased .5watt resistors and we tried again. Again it burned out the resistor. I have not been present either time when he hooked it up and plugged in the range, but each time I have bench tested it and the display comes on and buttons work. I am including some pictures and further information below.
I started to trace out the circuit, curious why there is so much draw causing the 10ohm resistor to open. I believe the power circuit is a switch mode power supply? Sorry still kind of a noob.
One 470uH inductor in series to and before the resistor on the line side seems to have a small crack but ohms out at 1.1ohms or so.
A few questions:
1. If I traced the circuit out correctly and the diodes make up a full wave rectifier, then why is one diode larger/different from the other three?
2. What seems to be the most likely failed component that would allow it to function on the bench but burn the resistor when installed in the range/oven?
3. Could the 470uH inductor be shorted? I read something about inductors in series on ac mains to reduce high inrush current on initial power up? Is that what this one is doing, and is this the correct function in this situation?
My circuit tracing efforts:
The two relevant pages from the service manual for the stove:
Board top and bottom:
R71 is the resistor that keeps burning up
D49 is the odd ball diode 1N5406, unable to read others while on board
I tested dc voltage after rectifier and it read approximately 160vdc as that is close to what I had in a simulator on my phone
L3 is the somewhat questionable inductor
Y3, MOV tested OL out of circuit
I apologize for the long post.
Thank you in advance for any help and feel free to ask any questions.
Robert
I am attempting to repair a control board for a gas oven. The initial fault occurred after a lightning storm, the digital read out and all oven controls ceased to work. Upon inspection I found a resistor on the line side to be open. I replaced it with a 1/4watt as that is all I had at the time. I applied power to the board while on the bench and it worked (display lit and buttons functioned), however when my dad plugged it all back in it "sparked, crackled and shut off". I then purchased .5watt resistors and we tried again. Again it burned out the resistor. I have not been present either time when he hooked it up and plugged in the range, but each time I have bench tested it and the display comes on and buttons work. I am including some pictures and further information below.
I started to trace out the circuit, curious why there is so much draw causing the 10ohm resistor to open. I believe the power circuit is a switch mode power supply? Sorry still kind of a noob.
One 470uH inductor in series to and before the resistor on the line side seems to have a small crack but ohms out at 1.1ohms or so.
A few questions:
1. If I traced the circuit out correctly and the diodes make up a full wave rectifier, then why is one diode larger/different from the other three?
2. What seems to be the most likely failed component that would allow it to function on the bench but burn the resistor when installed in the range/oven?
3. Could the 470uH inductor be shorted? I read something about inductors in series on ac mains to reduce high inrush current on initial power up? Is that what this one is doing, and is this the correct function in this situation?
My circuit tracing efforts:
The two relevant pages from the service manual for the stove:
Board top and bottom:
R71 is the resistor that keeps burning up
D49 is the odd ball diode 1N5406, unable to read others while on board
I tested dc voltage after rectifier and it read approximately 160vdc as that is close to what I had in a simulator on my phone
L3 is the somewhat questionable inductor
Y3, MOV tested OL out of circuit
I apologize for the long post.
Thank you in advance for any help and feel free to ask any questions.
Robert
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