resistor on toaster logic board

Mark Bax's picture

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Joined: Mar 15, 2020

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resistor on toaster logic board
March 15, 2020 - 1:04am

Hi I'm hobyist that is new on the forum. In a previous life, I worked my way through college with several jobs, one of which was working in a TV repair shop. I'm not new to electronics, but just a hobbyist none the less.

My toaster stopped working properly. I took it apart and saw that a resistor on what I assume is a logic board is fried. So much so that I can't read its value (see pictures). The resistor was R3 on the board - that charred spot in the center, just below the pot. Note that I did not have to use an iron to remove the resistor. It's short appaently generated enough heat to loosten it from the board.

Not surprisingly, the resstor reads open on the 20 Megohm scale of my multimeter. I would appreciate any suggestions about how to replace this resister. I was thinking I might wire in a high resistance pot, set it at max resistance and try the circuit. Then gradually reduce the resistance of the pot until the circuit works. Yeah, I know ... dicey, but not sure what else I can do. Yes, I bought another toaster; I thought I might be able to repair this one for use in our camper  :-)

Thanks in advance, 

Mark

 

Sourav Gupta's picture

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Joined: Feb 12, 2018

Replies: 220
Only way to help you by getting the schematic
March 16, 2020 - 11:58am

Do one thing. I assume that you have basic schematic reading and drawing sense. Sice the board is single layer, it is easier to reverse engineer the thing. Could you please draw the schematic from the board? Leave the resistor section value, just draw a resistor with 2 watt rating. Maybe we will able to provide you proper value of the resistor after checking the schematic.

Sourav Gupta's picture

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Joined: Feb 12, 2018

Replies: 220
You can make the schematic
March 16, 2020 - 12:04pm

You can make the schematic from the relimate that is situated behind the D24. Draw the whole section schematic from the relimate to the output of the bridge rectifier.

I am assuming that the relimate section is used for AC input purposes, after that it goes to the bridge diode, then the big capacitor, and after that the line is regulated using the DZ4 (It is not D24, sorry for previous reply). The resistor that is burned is used as a current limit resistor for the zener maybe.

Could you check that the DZ4 is dead or not? I assume it maybe dead short and caused this effect.