Mr. Coffee BVMC-TJX37-RB power board

[freakytiki4u]

I know this is a weird question lol, but I want to repair this board that came out of my coffee maker. It just suddenly stopped having power. I took it apart and this is the only board in the coffee pot. it looks like it has a blown resister. I can solder a new one in there but I have no idea what to get to replace it with. Anyone know what that is? I circled it in red where its labeled R3. Thank you in advance for any help. Is there a fuse on this board? If so, where?

[R_J]

Re: Mr. Coffee BVMC-TJX37-RB power board

Post a clear picture of the other side of the board, that could help. There are usually thermal fuses located in the coffee maker that may have opened causing no power. In this picture there is a thermal cutoff attached to the tube and 2 thermal fuses in series

[freakytiki4u]

Re: Mr. Coffee BVMC-TJX37-RB power board

Ok, thank you. Here is a picture of the back of the board.

[freakytiki4u]

Re: Mr. Coffee BVMC-TJX37-RB power board

With an Ohm meter both of the thermal fuses test good.

[R_J]

Re: Mr. Coffee BVMC-TJX37-RB power board

Did you measure that R3 resistor, it might be ok but just heat stressed, You might need to remove one end to get a good reading.
Do you get line voltage accros acl & acn ?
do you get any dc accross C4 Cap.?
Looks like ac line comes through C2 and goes through R1, is rectified by D1 & d2, filtered by C4 and dropped to less than 35volts (maybe around 25 volts) by ZD1. It then passes through R3 and is regulated by ZD2 which must feed the processor board.
If you don't any dc voltage accross C4, unplug the white plug with the 5 wires and see if that voltage comes up.

[sam_sam_sam]

Re: Mr. Coffee BVMC-TJX37-RB power board

To me it looks like a current limiting resistor this setup is use in LED nights it is very simple
you just need to know what the current draw of the controller and what ever else it powers

The best way to do this is if you have a variable power supply
Look at the caps around the power input of the controller board just make sure NOT go higher than voltage

This is to find out what your current draw do this carefully take your time doing this you can burn up the controller

Slow bring up your voltage until the controller powers ON and works the way it should

Then use Ohms Law to get what resistor you need to use
Just make sure to use 120 volt and what your current is
You might have to adjust the value of the resistor to have the right current value

Put the resistor value on the board and make sure that your voltage and current is the values that you need it, this is the voltage and current form your testing that you did

*************************************

The way I would do this if you have some high current LEDs or a MR16 20 watt light bulb just put enough together to get the current value that you need to have

Just remember that you are working with 120 volts AC which can hurt or can kill you so be careful when doing this last part *****************************

I hope this helps

[sam_sam_sam]

Re: Mr. Coffee BVMC-TJX37-RB power board

Did you measure that R3 resistor, it might be ok but just heat stressed,

*******

Looks like ac line comes through C2 and goes through R1, is rectified by D1 & d2, filtered by C4 and dropped to less than 35volts (maybe around 25 volts) by ZD1. It then passes through R3 and is regulated by ZD2 which must feed the processor board.
If you don't any dc voltage accross C4, unplug the white plug with the 5 wires and see if that voltage comes up.

You could also do this as well but I am going to add a little bit more
You could also hook your adjustable power supply to the the 35 volt capacitor and put 24 volts to the board and if everything works or not
do the same thing to find the current value you need to find the resistor value and test it same way this if the resistor measure open

[budm]

Re: Mr. Coffee BVMC-TJX37-RB power board

Check to see if Zener diode ZD2 is good or not (R3 feeds that zd2).

[supervolting]

Re: Mr. Coffee BVMC-TJX37-RB power board

Could someone with this model coffee maker please confirm how they were able to unscrew the base, or if they've had the same trouble I have.

The four back screws were simple as they were a standard philips. I cannot identify what the 2 front screws under the heat plate (hidden by rubber feet) are and I'm curious how others have disassembled.

[supervolting]

Re: Mr. Coffee BVMC-TJX37-RB power board

Using this site as a reference to an older model (https://www.instructables.com/id/Rep...-Coffee-Maker/) it seems to take a security torx. Hopefully I can get it off and post back in a new thread for some EE assistance.

Sorry for reviving this post. There isn't too many technical pieces for this model on the net.