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Thread: PX1 Power plug was with reversed 12V Polarity. What to replace?

  1. #1
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    Default PX1 Power plug was with reversed 12V Polarity. What to replace?

    So in another thread I mentioned that I had inadvertently connected the 12V power supply to one of my PX1 in reverse. The LEDs do not respond now when I put the wires from the power supply correctly to the board. Nor does it light up any pixels.

    But when I tried to re-program the PIC with the PICKit2 the LEDs came on and it was able to read/Write/verify the pic. So at least that part still works. The fuse is not blown (checked with a multimeter). But the plastic around the fuse looks like it was cracked (kinda like how super glue comes is contact with plastic). I don't see any other physical problems with the board, but what can be replaced to make it functioning again? I will try another fuse to be sure it not that.

    thanks

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    I swapped out the fuse from another working px1 and LEDs still don't turn on.

    Any suggestions??

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Hi, I would suspect the voltage regulator is dead:

    http://www.doityourselfchristmas.com...le:PX1-IC3.jpg

    If you measure the voltage with a probe on ether side of C2 what reading do you get?

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Quote Originally Posted by Barnabybear View Post
    Hi, I would suspect the voltage regulator is dead:

    http://www.doityourselfchristmas.com...le:PX1-IC3.jpg

    If you measure the voltage with a probe on ether side of C2 what reading do you get?
    I'll give that a shot tonight... I can use my multimeter right?

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Quote Originally Posted by Barnabybear View Post
    Hi, I would suspect the voltage regulator is dead:

    http://www.doityourselfchristmas.com...le:PX1-IC3.jpg

    If you measure the voltage with a probe on ether side of C2 what reading do you get?
    When I measure C2 I get 12.16V. Is that good or bad?

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    The voltage going to the CPU must be 5v. Please check the CPU voltage.

    2017 adding 2 more candy canes, 7 Mid trees and a Halloween show. Removing most 2812 strips and replacing them with bullet pixel mounting strips. Replacing many buck converter waterproof bags with printed boxes.

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Quote Originally Posted by MartinMueller2003 View Post
    The voltage going to the CPU must be 5v. Please check the CPU voltage.
    Where do I test that? looking at some schematics and stuff for the PIC. Do I just measure Pins 1 & 14 on the PIC??
    Last edited by PinakBERT; 12-07-2017 at 06:24 PM. Reason: read some other PX1 stuff

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Looking at the PIC with the notch/dimple on the left, then measure between pin 1 (ground, bottom left) and pin 14 (V+, top left).

    Jimboha
    Springville, Utah

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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    On the 16f1825, pin 1 is 5vdc and pin 14 is ground. The dot denotes pin 1. Unless I'm mistaken.

  10. #10
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Yep, but for the purpose of testing his voltage, either polarity will work.

    16f1825.jpg

    Vdd (drain, ground) is 1. Vss (source, Vdc) is 14.

    Or am I having a(nother) senior moment?

    Jimboha
    Springville, Utah

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