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    Jeroen
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Questions about strange behaviour with our ETC smartpack system

System description:

- Smartfade 24/96 with latest updates v2.0 and Smartsoft running on a laptop pc
- Smartpack Portable dimpacks in a touring flightcase on CEE three-phase (3N400) with software version 2.0.1 (I think).
- all 5-pin proplex dmx cables with correct impedance ratings
- different fixtures mostly 1kw and 0,5kw PC's, assym. floods/cyc. and pars

Problem/occurence:

We had a sequence of shows with a few dimmerchannels with a very low load, using several small 40w or less bulbs in a 'home made square matrix'. During the show, without a change in values from the control console, the bulbs suddenly flickered (twinkle). This happened very occasionaly and fast during the 1 and 1/2 hour show, but was easy to spot since they where backlighting.

Approximatly each channel of the dimmer had a load of 300w maximum, thus something like 0,8 A each on SmartPack portable 12x10A dimmers on three phase, if they would be at full, but they often were only at 30% or less, so I wonder is there a limit on the minimum load the Smartpacks need to nicely dimm tungsten type lamps? Does the low wattage has an impact on the dimming curves?

So would it make sense to add a 'dummy load' to those circuits to enable smooth dimming at all times without a twinkle now and then?

Is it possible that it has to do with interference on our powerlines (daylight savings), or interference on the dmx line (to close to power multicable  or sound cabling) to the dimpack?

Does perhaps upgrading to a newer version of Smartpack resolves tis problem?

 

All help greatly appreciated,

thx in advance,

J

 

 

 

  • Jeroen,

    I am assuming based on your other post that you are running this sytem on three phase power.  If not, please let me know whether you are then using bi-phase or single phase feeds.

    Are the loads 230V/40W or are they on magnetic or low voltage electronic transformers?  Di you only have problems with the 40W loads or were the porblems across all the different load types?

    Let me know,

    David

  • in reply to dnorth

    hi David ,

    Running on 3 phase power (3x380/400 + N + G) 5pin CEE

    Loads are 230V/40W, all small E27 lamps in sockets no transfo.

     

    We only noticed the problems on the small 40w fixtures, because they were pointed towards the audience / foh booth, we did not notice any strange behaviour on the other devices (1kw pc / fresnel, pars)

    , J



    [edited by: Jeroen at 1:04 PM (GMT -6) on Wed, Jan 7 2009]
  • in reply to Jeroen

    This is in France? right?  It may be due to mains signalling.  France implements a 175Hz ripple control signal several times a day to change electricty meter tariiffs.  That is a possible cause.  That ripple is only visible on low wattage lamps and is seen on ordinary domestic lighting from time to time.  It has also been observed in Austria on low wattage dimmed lamps when a similar signal is present.

    The other possibility is a DMX fault resulting in very short-term intermittent data loss or corruption.  Again, if the duration is very short it would only show on low wattage lamps with low thermal inertia.

    40W is a high enough load to ensure proper dimming in normal conditions.  Smartpack can dim lamps of a much lower power, 25W is OK and dimming is acceptable with only 5-8W (@230V).  So, it is unlikely that the problem is due to low load.

    There are two things you can try to identify the problem: 
    1.  Leave the dimmer running with the affected loads set at a dim level via the test function, with no DMX connected.  Does it ever flicker?
    2.  Attach a large dummy load to one of the affected channels, hide the load (lamp) so it cannot be seen.  Does the flicker stop on that channel?

     

  • in reply to AdamBennette

    Thank you for the response and the indication of minimal load for the smartpacks.

    We observed the behaviour in Belgium, I wonder if it is the control signal to change tariffs, then it would only occur once? For example at 21h when the tariff changes, or is the signal send continously?

    A good suggestion to indentify the problem by testing out... I will try to do so, and construct a similar situation to test, since we moved on to the next production.

     

     

     

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