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Troubleshooting

JojjelitoJojjelito
edited July 2013 in General
Slapped together the big PCB except for LEDs and OLED in 2 hours. The PSU seemed nice at the first checkpoint, but when I got to the ISP header check there was no joy. The reg got hot so I unplugged it and started to measure a little before calling it quits for the evening. Stupid me got eager thinking it's an easy build (it was!) so I skipped periodic checks of the PSU... Anyhow

There was hardly any resistance between GND and 5V :-? Something major is amiss! I pressed down the display connector until it bottomed out before I soldered it. Better check that there's no metal under the DIN sockets. I guess I should find and print the PCB layout and follow the schematic if replacing the regulator doesn't help. Also, better measure continuity plus check the board under a microscope for any hidden connections. I used Kester 245 no-clean solder as always and it flowed nicely. I did not put too much solder anywhere as far as I could see. Better check the board for vias close to any pins just to be safe. Plus retouch all joints just in case.

Is the PCB layout available for troubleshooting? Gonna go check tomorrow.

The PSU polarity and voltage is correct.
The PSU caps plus diodes are in the right direction.
Something to sleep on...

Comments

  • julianjulian
    edited July 2013
    on a completely build unit i measure around 2.8K resistance between 5V and GND.

    Here is a picture of the PCB with the GND and one with the 5V traces highlighted
    On the bottom layer the whole copper plane is GND, too.
    imageimage

    but first of all sleeping sounds like a good idea!
    I-)
  • JojjelitoJojjelito
    Cool! Many thanks.

    Yup, figured I'd probably do more harm than good after the Zerg rush type soldering session tonight. Better to look at the problem with more rested eyes ~O)

    2k8 sound better than the very low value I got! It's probably something easy once I find it.
  • JojjelitoJojjelito
    Found the error this morning: There was a piece of tin that was hard to see between a leg of R28 and the Filter switch. Figured as much, had to be something simple  :)>-

    That was my first soldering mistake since a few years back when I made the 9090. Guess those keep you focused. Pics taken, but I need to upload them somewhere before I post in case anyone's interested.
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