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Thread: PSU troubleshooting

  1. #1
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    PSU troubleshooting

    Afternoon,

    I've just been flying most of the morning using the PSU/TBS69/Lawmate 2.4 500mw combo, and for 99% of the time, it was awesome. Totally flawless.

    Towards the end of one of the flights I took the goggles off and gave them to my brother as I did a couple of circuits LOS, and about 10s before landing, the video dropped out totally. Just went to static.

    I landed LOS and we tried recycling all the groundstation power to check if it was a problem with that, the video remained static though.

    Recycling the power on the wing by unplugging and plugging the batteries back in fixed it though, which is a bit mysterious.

    I was just wanting to eliminate the PSU from the troubleshooting - when it's turned on the green light flashes quicky for about 5-15s before the light goes solid and the picture comes online. Is this normal?

  2. #2
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    let me ask RiSCyD what this could be. If I know it correctly then the LED is directly wired to the power output, which means the intensity of the light correlates with the voltage supplied. Can you check if there might be a short or intermittent connection in the cables? Maybe the camera is defective. There is a protection circuit in the PSU which shuts it down if it is being strained (e.g. reverse polarity) or a 12V Vtx. Did you get the wiring done by us? Post a picture of it here, I will verify what I just said with RiSCyD and report back.

  3. #3
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    I've been fiddling around with wires in the equipment bay to try and reproduce the fault but no such luck so far. When the video dropped out there was nothing whatsoever broadcast, just static - no OSD parameters on top of it.

    Wiring was done by yours truly, it's all on a Scout Bee.







    Only changes since these pics were taken a few weeks ago before lamination have been the PSU power supply cable from the current sensor and servo wire routed behind the bay have been twisted.

    Does your PSU/video come online instantly as soon as you plug the LiPos in?

  4. #4
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    Hi Pooch, define "instant". It takes about 2-3 seconds after hookinh up the battery then the VTx and camera come online. We had a quick talk, the behavior the PSU shows is not normal. So, let's find what's causing that:

    disconnect VTx and camera, then power up your system: If the LED still flashes randomly, check with a magnifying glass for shorts or wiggle the wires as good as possible to see if you have a faulty connection or short somewhere on the two outputs or on the input itself. If that is not the case plug in the VTx first, repeat. If the problem shows up now, you've got a faulty VTx. Otherwise hook up the camera, see if the flashing LED is now happening. If not, you can send the PSU in for repair and we'll take a look at it, clean it up and send it back to you (no charge, obviously) just to make sure it's not the PSU. If it's either of the two components shoot me an e-mail, we'll replace them.

  5. #5
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    Okay, I'll give it a shot and get back to you. Cheers.

  6. #6
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    Right, this has got me totally confused now

    With the PSU powered and both the VTx output from the OSD and the camera input from the OSD disconnected, the LED goes straight to solid green.

    With the PSU powered and either the VTx or camera connected via the OSD, the LED goes straight to green.

    The problem occurs when both the VTx and camera are connected at the same time. As before, the LED flashes quickly initially (the speed of the flash can vary a bit), for anything from 3 or 4 seconds to about 30s actually before going solid and the picture will come up and be totally perfect.

    Does this give you any clues?

  7. #7
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    Chopped the laminate and covering away and took a couple of macro shots of the whole thing.

    http://imgur.com/a/3zwSW#1

    There are no shorts I can see on the wiring at either end - it's something I checked fairly obsessively before putting the blob of hot glue on as stress relief and burying the unit. I've given the whole thing a blast with compressed air and the symptoms are the same.

    One thing I noticed on the macro shots was (apart from that my soldering doesn't look half as good when it's supersized ) there appears to be some bridging on the right hand legs of IC1 - whether this is solder or just some residue I don't really know.

    Thoughts?

  8. #8
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    Pooch, please send it back in for repairs. I'm not sure what it is, but your soldering is spot on and the behavior you described leaves me worried. If you can, please also send back the camera and the VTx. Whatever you send us will be replaced, obviously.

    Send me an e-mail with your address, I'll have everything mailed to you by middle of the week to minimize downtime.

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