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Old VL2000 not powering up

Discussion in 'Lighting and Electrics' started by macsound, Jul 13, 2018.

  1. macsound

    macsound Member

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    Hey all
    I have some VL2000s that were packed away about 7 months as working but now I have one, so far, that isn't turning on.
    It seems like an old PSU, but want to confirm here.
    When I turn it on, theres a subtle click and one of the lights on the LCD flashes. When I first plugged it in, the click was quieter and the light flashed dimmer. Almost like one of the capacitors is dead and leaving it on for a few minutes is charging it.
    I've had issues like this on a computer power supply, but want to make sure it won't blow up if I leave it plugged in for an hour to see if it eventually turns on.
     
  2. TimMc

    TimMc Well-Known Member

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    It probably won't blow up but it might smolder/smoke or spontaneously generate an assistant electrician....

    You might want to give a call to Used lighting dot com and inquire about replacement PSUs....
     
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  3. macsound

    macsound Member

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    So got an email about my inquiry from the company I originally purchased these VL2000s from and they said the power cable can sometimes be weird DEPENDING ON THE FIXTURE'S ORIENTATION.
    Caps part is what caught my eye.
    Is there a sensor for direction of installation that limits power? My understanding with these is they can be operated in any orientation, and if nothing else, sitting flat on a stage seems normal.
     
  4. TimMc

    TimMc Well-Known Member

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    My direct experience with VL2000s is putting them in road cases... but I think the vendor is saying "the F*&#(!#@ power cable gets loose in certain positions."
     
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  5. Les

    Les Well-Known Member

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    I take it to mean that the power cable has some loose connections and may not make contact when oriented a certain way...

    Edit: Posted concurrently with the above. Look in to the cable - both the connector and where it enters the fixture (on both sides of the strain relief/panel-mount connector if applicable). If it's dickey (technical term), you'll want to get that sorted as not only is it an annoyance, but a fire and shock hazard.
     
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  6. macsound

    macsound Member

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    Took off the covers last night and all the power cables seem normal. Ground is bolted down and +- connect to the transformer, then to the power switch.
    Even removed the power switch because the cable comes through the body underneath the switch, so I wanted to check that there isn't some twist or sever.
    The weird thing about this light is the PWR light flashes on the front panel once every 5 seconds and you can hear some electrical transformery noise. And when I powered it up with the cover off, you can see the fan do a wiggle concurrently with the PWR light flash.
    My feeling is that initial transformer (not the power supply) isn't happy.
    I guess I'll start forking together some parts from a working model to pinpoint the problem unless anyone else has an idea.
     
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  7. FMEng

    FMEng Well-Known Member Fight Leukemia

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    Repetitive blips of power is a fairly common symptom of a dead, switching power supply. Not likely the transformer as they don't oscillate, they just quit. More likely dry electrolytics on the supply board.
     
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  8. JD

    JD Well-Known Member

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    To expand on the above post: You put it away and it was working, pull it out months later and it doesn't = Capacitors.
    Caps tend to drop in value when they are cold. Best example is a computer that has been on for years, turn it off, clean it all up, dust it out, and you are rewarded when you hit the power switch and it fails to start back up.
    Caps also drop in value while in storage. Usually this is due to a failure already in progress in the capacitor that gets worse when the unit is not powered up. Caps also dry out with age, especially if the seal is already cracked.
    When you line up all the parts; Transistors, diodes, resistors, ICs, chokes, etc., it is the capacitor that follows the above symptomology. The bigger the cap, the more likely. The biggest caps are found in the switch-mode power supply.
     
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  9. FMEng

    FMEng Well-Known Member Fight Leukemia

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    JD has it right. The other tip for finding the bad capacitors is always suspect the ones in warm places, such as adjacent to heat sinks, first. Their llife span is greatly reduced by temperature. Since power supplies often run warm, they die there first. I usually replace all the electrolytics on the power supply at once. The parts are cheap, and it takes less time than troubleshooting to the component level.
     
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  10. JD

    JD Well-Known Member

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    One last quirk about switch-mode power supply capacitors: Besides usually having a higher temperature rating on the case, caps used in these supplies are designed to have a very low self-inductance. See, capacitors can really be thought of as a capacitor, resistor, and inductor wired in series. Just the nature of the beast, what with the long cold of metal film. For switch-mode supplies, the caps are designed to have very little inductance and resistance as the high-current at high frequency would contain a lot of ripple. When in doubt use OEM caps as the off-the-shelf ones could leave you with unexpected problems.
     
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  11. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @JD @FMEng Writing in support. When I moved to Stratford, Ontario's, Stratford Shakespearean Festival's main stage to become their IA Head Of Sound, the SFX playback system I inherited included a 44RU rack housing twelve Crown D150 stereo power amplifiers driven by their custom Ward Beck 12 x 24 matrix effects console and powering 24 effects speakers, mostly Tannoy Belvederes, throughout their auditorium, stage, and backstage areas. Prior to my arrival, it had been their standard policy to power all of their amplifiers off between performances and rehearsals, even on matinee days. Coming from a 24 / 7 / 365 commercial AM broadcast background, I chose to leave the amplifiers on 24 / 7 / 365. Prior to my arrival, it was common for them to lose one channel several times per season whereupon they'd pull the stereo amp and ship it to Toronto for repair leaving them minus two channels for the duration. My approach was different; I purchased a 13th Crown D150 as a spare and installed it on the rear rails of the same rack with a pair of input extension cables and a pair of output extension cables coiled adjacent on hooks allowing me to swap the spare amp into service between cues if / when required. I learned the most common failure mode was one of two identical capacitors in each D150's power supply. At the end of my first season when it had been determined I'd be kept on by the Festival, I ordered two OEM capacitors from Crown's Canadian rep' in Toronto for stock and that was the end of shipping Crown D150's to Toronto for repair. What I learned was if the amps were powered for the season, they rarely failed. I'd power them down for the winter months and re-power them upon my return. If they re-powered successfully, they were most likely good for another season. If one channel was humming loudly upon powering up, I'd determine which amp it was, swap in the spare amp, pull the faulty amp, replace both of its capacitors, test it, reinstall it as the spare and order two more OEM capacitors for stock. The Crown amps continued to percolate happily for the remainder of my time with the Festival.
    Toodleoo!
    Ron Hebbard
     
  12. JD

    JD Well-Known Member

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    Yea, have a couple of old DC 300's that prematurely clip, or at least light the I/O lights. Suspect Electrolytic Capacitors have dropped in value (both from the 80s.)

    Capacitors are a problem in both lighting and sound systems. Their chemical nature is problematic for long term storage as they decay unless there is voltage across them. They may work when hot, but crash in value when cooled off. And yet, heat kills them!

    Said server in post #8 I got up and running to move data off of it by heating the caps in the supply with a hair drier.
     
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  13. FMEng

    FMEng Well-Known Member Fight Leukemia

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    Some suppliers carry low ESR capacitors, made for switching supply duty. Digi-Key is one that does.
     
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  14. macsound

    macsound Member

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    Incredible responses folks. You are all amazing.
     
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