Heatmeter won't boot 12v will boot off PI power


 
RalphTrimble said:
Yes, the circuit board where you have marked in purple is the 12V to 5V converter. Pin1 is the input(12V) Pin 3 is the output (5V/YELLOW) Pin 2 is GND(Gray)....

IDK what it reads like in circuit, if you measure a dead short between any of the pins I would pull it out of the board and then apply 12V to the HM board and see if you can measure 12V at that point.....
Click to expand...

I de-soldered the 12v to 5v board and then connected the 12v power to the HM. I am able to get 12v on my meter at the back barrel jack and from the and from the ground by the probes to the 12v + on the fan jack. So the 12 to 5v is probably DOA?
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Steve
 
I tested the 12 to 5 converter in the breadboard connecting 12 to the 12v lead and testing from ground to the 5v on my meter and it got 4.9 something so the converter is working. I soldered back on the barrel connector and went to test the 12v again on the HM and cannot get a voltage reading. I tried on the barrel and on a few spots nothing. I remove the barrel again. I think I shorted something adding the barrel back on now when I plug in with just the PI I get screen flashing then solid blocks on the top line. Guess my soldering needs some work.
 
You can test it by soldering wires to the 12V in and GND while you've got it out of circuit then measuring the voltage on the 5V pin. You can also measure the resistance between the pads on the PCB where you've removed it. It should be somewhat high. I'm nut sure how high but more than 100 ohms no doubt.
 
I've got a spare, measuring with a multimeter is hard because the values are not stable, they rise or fall depending on what pins you're measuring. The resistance should be high at any rate, if you measure anything like a stable low resistance between any pins I would say it's dead....
 
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