Pretty sure I know the answer to this but thought I'd ask here anyways. Got this nice coffee maker from someone since it just died on them. Long story short a surge blew a fuse and MOV in the power supply. I replaced both and tested, machine came back to life! Decided to try to take a video to show a friend and that's when I heard the relay click on and water start boiling in the tank and the display/buttons are now dead again. Did a bunch of testing, couldn't figure out why this is happening, every time I plug it in, the heater turns on via the relay. To try and test more things, I decided to desolder the relay to stop the heater from coming on. Well now some of the buttons at the bottom started lighting up a bit and unfortunately found out what seems like the CPU is running at over 100c (my poor finger 😣). Is there anything I could look at or is this poor board just toast?
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check the voltage regulator cicuit isnt shorted and overdriving the cpu
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Excellent suggestion! Unfortunately I'm really not sure which circuit is for the voltage regulator or how to test for this potential short. I've attached some pictures to show the board itself and from what I've found Vdd is only on pin 11 (pin 1 is directly under the dot). If you could kindly bump me in the right direction to test for shorts, I would be very grateful!
https://imgur.com/a/SPU6GM1Attached FilesComment
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r26 and r27 look a bit toasted,
check all the resistors with a meter
whats on the other side?
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R26 and R27 are fine (4.66k and 4.67k). Testing the rest of resistors will take a long time but I will test them. I've attached an image of the back of the board as well. Looks like the only thing of note is a crystal oscillator and a capacitor (which the CPU is right on the other side of the cap).
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Have you checked the voltage coming from the power supply? looks like it should be +5v (red wire on white plug)Comment
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i didnt think of a seperate psu!
nice that the connectors are labeled!
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