Testing PCB

This topic contains 7 replies, has 5 voices, and was last updated by  Chris 3 years ago.

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #2397

    bmyk
    Participant

    Hi all,

    I am building the PCB from Hobby CNC and have arrived at the testing step (to assure proper voltage before installing the chips). As one may recall, you have to apply a voltage between 12-42VDC to assure proper readings. To apply this voltage I am using an old wall adapter that is 15VDC @ 1A. When applied, my multimeter reads only .5VDC. I have tripled checked and gone through all the steps and have found no errors in my build thus far. Does the amperage of the wall adapter have anything to do with this problem? Should I be using a battery instead? What did you use to test with?

    Thank you in advance!

    #3832

    markm
    Participant

    Where are you measuring the voltage? If the0 .5V is the output of the wall wart when connected, look for a short between power and ground. If the 0.5V is the output of the 5V regulator, then look for a cold solder joint, probably at the LM317 regulator.

    Either way, time to get out a magnifying glass and a strong light and check for solder bridges or cold joints.

    #3833

    bmyk
    Participant

    I am testing by placing the negative lead from the voltmeter on the “-” symbol near where it says 42V and then applying the red lead to the spot that says +5, as directed.

    I did as you suggested to no avail…

    Help! Anyone!

    #3834

    Taylor
    Keymaster

    @markm,

    Wall warts are notoriously flaky – you’ll see that they give different voltages depending on where in your house you plug in. Is there any reason you’re not testing with the full-scale transformer that’s called for in the build?

    #4531

    mortegah
    Participant

    I have the same error, did you solve the problem?

    #4535

    Chris
    Keymaster

    mortegah, what are you using for a power supply? Specifically, what are the specs for voltage and current? This could be causing problems, also it could be an improperly soldered connection (all it takes is one!)

    #4536

    mortegah
    Participant

    Im using a Plug In Class 2 Transformer from an old device.

    It has an input: 120VAC 60Hz 15W and output: 12VCD 800mA.

    What kind of power supply should I use?

    thanks for your reply

    #4537

    Chris
    Keymaster

    My guess is that your current transformer might not be able to supply enough current (even though the voltage is correct). The HobbyCNC specs call for a 10A power supply, which is what we’ve had good results using on the DIYLILCNC (though other setups might need more or less current).

    If you have access to a benchtop power supply , you can dial in the amount of voltage and current you need. Otherwise you could get the transformer, capacitor, and other parts needed to build out the HobbyCNC power supply before completing your tests.

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