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Voltage regulator circuit now won't regulate

Discussion in 'Troubleshooting and Repair' started by That8BitMan, Nov 27, 2014.

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  1. That8BitMan

    That8BitMan

    5
    1
    Nov 27, 2014
    Hey guys,

    First time posting and I'm just gonna start of in saying that I don't know much about electronics. I made this solar phone charger using a 10w solar panel and the Improved Low Voltage Adaptor from Jaycar (elecronics shop in Australia. Some info here, product page here). The last time I used it, it worked great although it got quite hot so I decided to modify it a little.

    I bought a bigger heatsink for it as well as some new connectors instead of the wires soldered straight onto the board.

    Before I modified it, it was working fine but now, it only takes off 1-2v from the voltage that the PV cell is outputting instead of dropping the voltage down to 5v.

    How would I go about troubleshooting this? Have I missed any crucial information? I'm really unsure.

    Any help is appreciated.

    ~8Bit
     
  2. chopnhack

    chopnhack

    1,573
    352
    Apr 28, 2014
    How many volts was the solar panel producing? Can you read the print on the voltage regulator? Is it a LM317?
     
  3. That8BitMan

    That8BitMan

    5
    1
    Nov 27, 2014
    The solar panel was producing ~19V. The voltage regulator is the LM317T.

    I just checked again and it produced around 16.8v (I'm inside so I'm pointing it out the window) and at the output terminals of the buck converter, the voltage was 16.0v
     
  4. chopnhack

    chopnhack

    1,573
    352
    Apr 28, 2014
    So that's where the sun went :D

    The LM317 is not the most efficient regulator around, so some voltage drop is to be expected.

    Edit: - You said that 16v after the buck converter - do you mean at the ouput?
     
  5. That8BitMan

    That8BitMan

    5
    1
    Nov 27, 2014
    Yeah, at the output terminals on the actual circuit board. It should be giving me 5v. There are jumpers to select the output voltage and even with the jumper off, it gives the same reading. I'm starting to think it's my soldering job although I can't see anything wrong.
     
  6. chopnhack

    chopnhack

    1,573
    352
    Apr 28, 2014
    Are you able to take pictures of the board? There is a good resource on how to post pictures of pcb's to the forum for aiding members. Take a look at it and post some pics. If the output is mimicking the input, then there is either something wrong with the resistance on the adjustment pin or the v.reg is fried "on" (continuity).

    Take power off and check for continuity between pin 1 and 3.
     
  7. That8BitMan

    That8BitMan

    5
    1
    Nov 27, 2014
    So I tested the resistance across pins one and three (which I assumed were the ADJ and VIN pins) and it doesn't seem to give me anything. I've found a cheap regulator at Jaycar so I'm just going to get that instead of messing about with the one I have. It should be more efficient so I'll just go with that.
     
  8. chopnhack

    chopnhack

    1,573
    352
    Apr 28, 2014
    Interesting, the regulator may be ok then... Ok, keep us posted.
     
  9. That8BitMan

    That8BitMan

    5
    1
    Nov 27, 2014
    Sure thing man. Thanks for your help
     
    chopnhack likes this.
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