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Thread: Bizarre simpledrive II driver problem

  1. #1
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    Default Bizarre simpledrive II driver problem

    So, I installed a two new simpledrive II that were left over from a project a few years back. I set the currents on my bench like normal. Next, I installed the drivers in the projector (after shorting the outputs). When I powered up the projector I saw a brief a bright blue flash. I thought it was strange as i hadn't seen a SD II do that before. Everything looked good after that. I ramped the current up and down with my potbox. I turned off the projector for a few min. When I turned it back on the same blue flash. this time it took three diodes to laser heaven and one is now low power. F@#k!!

    I removed the driver and put it back on my bench. I hooked up a 1 ohm dummy load with my scope across it. The initial pulse was too fast to see on my scope. However, I did see a brief "flicker" of the trace. After about 5-10 power cylces the "flicker" of the trace seemed to go away.

    Next, I pulled the projector over and hooked the diodes back up. No light "pulse" on power up this time. Tried a few more times, nothing. The remaining weak diode still worked when modulated. Crap. I'm now thinking my projector supply is doing something strange. I hook the projector supply up to the driver on the bench. Now I am back to the original set-up that killed the diodes except the driver is on the bench and not in the projector. No pulse at turn on and the power supply looks good on the scope.

    Here is the set-up when the failure occurred:

    12.5V on the supply feeding 2X simpledrive II. One feeding 2 1w greens on channel 1 and 1 1w green on channel 2. The second SD II had 2 M462 diodes in series on each channel.

    I'm really scratching my head here. Anyone got any theories on what happened?

    I did check to make sure none of the + or - leads on the diodes were shorted to the baseplate.

    Obviously, I not gonna use the driver again. I'm grateful that it wasn't the 1w greens that got toasted. But a little nervous about not knowing what happened.

  2. #2
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    Nov 2010
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    Default

    PM received and it really looks bizarre.
    To completely kill the diode, the current must be more than 5A and a pulse wide more than 50-100ms. I'm not sure if this is true for m462, I tested it for m140 a couple of years ago.
    Only a pulse of reverse polarity can guaranteed to kill these diodes. If this is so, then we are dealing with some kind of oscillation in the output circuit.

  3. #3
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    I had the same thing happen to me as well. After blowing out two SM diodes, I decided to hook mine up to a 5W Cree LED. When I applied power to the driver with 0V on the modulation, the LED flicked on really bright for a fraction of a second and then the driver worked like normal. I found this to happen on 2 dual ch drivers that I have, both channels on each driver. I never did suss out what caused the issue. Needless to say, those drivers have been sitting in a drawer ever since.
    Last edited by absolom7691; 07-04-2017 at 22:09.
    Those who fail to grasp art are the ones who criticize it.

  4. #4
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    I did not have so many of those two-channel drivers to accumulate enough statistics on them. In any case, I have to replace them with new ones.
    I have a pair of projectors in sight, where those drivers are used - I'll try to investigate them more carefully when possible.

  5. #5
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    I was thinking of putting a 4000f or larger cap on the power input to "soft start" the driver but I never got around to testing out that idea.
    Those who fail to grasp art are the ones who criticize it.

  6. #6
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    I'm afraid to recommend using this board anyway. I have a suspicion of an open pot that I used there - it can oxidize over time, but that's just my guess. I refused to use open pots in my new devices, but this will help you in case you replace your SDII with them))

  7. #7
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    Thanks for the input guys. At least this puts my mind at ease that its probably not something else in the chain I overlooked.

    I wonder if a drop of pot cleaner/lube would be advisable for SDII users. Then work the pots back and forth (power off). This maintenance might save some expensive diodes if the pots are prone to go bad over time.

    BBE, can you describe the adjustment of the pot?

  8. #8
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    ... I have several high current drivers, which produce spikes when swiching ON or OFF - sometimes with peak currents of up to 300% of the set max. current!

    This spikes are pretty short (some hundred nanoseconds to 1 microsecond), but will reduce the lifetime of a diode drastically or blow it away pretty fast, when the reverse voltage is high enough.

    For this I've developed and use my own drivers ...

    Viktor

  9. #9
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    Nov 2010
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    In this particular case, we are dealing with some technical malfunction, unfortunately, I can determine what exactly happened, only when check this driver. I broke up with my last SDII 2 years ago and now I have to ask for help to get it again

    This pot is the adjustment of the quiescent current. Don't think that lube will be useful to recover it.
    BBE, can you describe the adjustment of the pot?
    If the driver is very fast and the connecting wires are very long then inevitably there will be oscillations when switching. SDII is not so fast and has a start delay, but here we see a kind of spike when powering up. Here's clearly something broken or deffective
    ... I have several high current drivers, which produce spikes when swiching ON or OFF

  10. #10
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    I purchased several SDII to BBE and honestly 100% working good...so it seems a bad luck with a defective driver ?
    Do you power with Lab PSU while adjusting? Which brand is your PJ PSU? I got 4 P73 killed by a chinese 'no brand' PSU months before...now all seems OK with Meanwell

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