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Jevans

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    John Evans

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  1. I can't claim any knowledge of those spots specifically, but I'm aware of a number of devices where there's high value resistors between line/neutral and earth. This should be called out in the user manual. For example I've definitely seen a 6 way dimmer pack with a ~100s of kOhm resistor between neutral and earth which fails an insulation test, but the resistor is intentional - either for EMI suppression or surge suppression, can't remember which! So this may be a similar scenario.
  2. Assuming you mean the 'LED only' style cuelights rather than the one with the screen - I did exactly this a few years ago. We bought the OEM packages to go in MK Metalclad/Edge style panels to on existing containment rather than buy any of the premade outstations. I also reverse engineered the circuit so that we could build ones with massive buttons and LEDs for the fly floor (sounding familiar!) I do remember clearly that the circuit on the OEM board wasn't at all in the order I was expecting - and interestingly, also didn't match the circuit diagram that GDS made available for the OEM module which seems to have disappeared from the internet, but it seemed to work. There are diodes in series and parallel with the LEDs, the purpose of which was unclear - other than maybe adjusting the voltage drop? I've attached the note I made myself at the time but I give no guarantees of usefulness! Whatever I ended up doing, I didn't use a circuit board either, I just soldered the components onto the legs of the buttons and LEDs and it all worked fine. I think I adjusted the resistor values to suit the different LEDs we were using; the controller is only able to source a certain amount of current though so anything beyond a simple LED will need a more complex circuit.
  3. The last few editions of BS7671 make it very difficult to not install RCD/RCBO protection on any 13A or small IEC 60309 socket outlet. I don't have the new exact wording in front of me, but my recollection is a written risk assessment is required to be filed with the electrical installation certificate, and the outlets are required to be under the control of a 'skilled' person. That wouldn't work - the terminals on 13A sockets themselves aren't rated to 63A. Generally they're also not rated to have multiple 6mm cables in the terminals.
  4. Depending on the fixture type you may get less fixtures on a circuit than you might like. I know from bitter experience a C10 curve RCBO won't reliably take the inrush current of more than 2-3 ETC Source4 Series 2 Lustrs for example, as they have a very high first half cycle inrush (107A on the spec sheet!!) Other fixtures may have inrush limiting components built in. It's not entirely clear from your description if you're intending to use the protective device (RCBO) itself as the means of functional switching, but I'd recommend specifying a separate switch or contactor to use for the functional switching rather than regularly operating the protective device - if anything, this will mostly prevent volunteers accidentally switching off the wrong circuit. As themadhippy says, Amendment 2 to the 18th edition of BS7671 which came out a few weeks ago has effectively discontinued the use of type AC RCDs, as they are now only permitted for fixed equipment which is known to not use DC components.
  5. The venue I used to work for had two sets of ArcSystem Pro kit, the main houselights were installed in 2016 with some extras in 2018 in lobbies. The 2016 stuff has been absolutely fine (and I should say that the whole system was hardwired from the start - the 2.4GHz band being very congested there) but we had lots of trouble with the bits we bought in 2018 - almost everything had to go back and be replaced. This was around the time that GDS was going through the process of moving/selling the ArcSystem range over to ETC, and the dealer told us at the time that we weren't the only people having QA issues - something about issues with solder joints in the fixtures. I've heard a couple of versions about what was going on at GDS at the time and it wouldn't surprise me if they were going through a rough patch. I don't remember if the replacements ended up coming from ETC rather than GDS. We also bought some BluesSystem kit at the same time, which has as far as I know been fine. That said, we did buy the 'mains' version of BluesSystem to retrofit to existing circuits, not the extra low voltage/dimmed version, so there's less to go wrong. The mains version got discontinued when ETC took over - I've asked and apparently the numbers being sold didn't make it worth it compared to the ELV version with the driver that most people buy - so if it's the mains style you have you may be out of luck.
  6. Jevans

    ECS Cards

    They no longer offer that particular one (like the main CSCS scheme, they keep fiddling with what they recognise) but there are similar cards available through partner schemes such as AV Engineer etc - see for example here. CSCS no longer offer a general 'Visitors' card, which has created issues for senior staff/consultants in some unusual disciplines (ours included) who don't have any of the recognised qualifications. On the other hand, a fresh graduate from any engineering degree can get one no problem by sitting the H&S test... in my case I could get one through membership of the IET. Never been asked for it!
  7. Welcome to the forum! As you've discovered for a two point hang it's fairly easy to work out using moments without knowing anything about the truss itself. Unfortunately as soon as you go to a multi-point hang things get a little more complex. If you try and set up a system of equations in the same way that you have you won't be able to get it to solve neatly - for example, for a three point hang, a single point load (and ignoring the mass of the truss) you have three unknowns (the load on each motor) but only two knowns (the load weight and the position fo the load on the truss) - can't be done. The key thing you're missing is how much the truss bends when the load is imposed, which obviously depends on the truss. In structural engineering terms, a two point hang is a 'statically determinate' structure, and a three point hang is a 'statically indeterminate' structure. There are various rules of thumb you can use which it sounds like you've found - often in a theatre/events context even if the load isn't exactly uniform it's close enough that these rules of thumb are useful, and also that there's often a large margin between the SWL of each individual hang/motor and the actual load. It goes without saying that you should consult a suitable qualified structural engineer if you are at all unusure about what you are doing or are doing anything complex. For proper calculations from scratch, the material properties of the truss are used with some calculus to work out the 'bending moment' at each position along the truss as well as the deflections - I'm not a structural engineer myself so I'm afraid this isn't a very satisfying answer, but sadly it's not as easy as it looks!
  8. Just to throw in another alternative - Yamaha make the MRX-7, which is more of a configurable audio DSP than the more general purpose Q-Sys boxes. More Dante native than the Q-Sys but slightly less general control options - has GPIO, an Ethernet based API etc. but is a bit more limited in what you can do with it. There's also the MTX-3 and MTX-5 in the same range which are fixed configuration rather than designable DSP, and are fairly standard paging/bakground music type processors.
  9. Not so obvious in my experience - at least when was buying stuff on account with Thomann some years ago, we paid in GBP to a UK account, even though the invoice one receives is in EUR. Our accounts team got it wrong a couple of times and had to talk to Thomann to get it sorted out; I know that it was one of the suppliers they had do a special case to make things line up on our system. My somewhat hazy understanding was that they did enough sales in the UK that it was worth them registering a subsiduary in the UK and handling transactions through it, eating the currency exchange fees etc themselves. Or something along those lines, I wasn't very clear! There is some information on the validity of CE marking on the gov.uk website; it'll still be valid for some time depending on category, but it'll gradually be replaced with the 'UKCA' mark. Needless to say there's still some details to be worked out...!
  10. Lots of sensible thoughts from dje here; I wouldn't in the slightest consider a small DJ-class mover equivalent to a Source 4, particually a mover that only costs a couple of times more than a conventional S4! Another important consideration for me, particually in small venues, is noise. Although conventionals usually have the fillament sing, movers have motors, fans and switch mode power supplies, and particually in FOH positons this can get very exposed to the audience. If you're doing a rock musical, fair enough; but I've been in the position of lighting drama with some noisy movers up FOH, and sensitive dialogue scenes are pretty much ruined for me by the noise of many fans whiring away overhead. You'll never get that 'pin-drop silence', even when you're not moving anything the motors may need to be active to hold the head in position against gravity. The sound designer isn't likely to be too keen either... Also consider repairs and maintenance - there's not a lot to go wrong on a conventional profile (unless you drop one and smash things...) and almost nothing that can't be fixed with a multitool; the only spare I think I've really had to fit to an S4 is the lamp base/tails. For movers - electronics, PSUs, motors, mechanisms, sensors... and the cheaper the brand the less likely there will be spares availible at all, never mind in 10 years. A really cheap mover is more likely to be 'disposable' - when it breaks it's gone. Depending on your use case/cost structure this may be acceptable for you - or it may not. I'd be thinking laterally about the problem - if specifically focusing a basic frontwash for one-nighters is the issue, could a second set of S4s be rigged on another bar and left permenantly in that focus? Perhaps a simple deadhung bar nearby, leaving the current bar for a 'focusable' set of fixtures. Or turning the existing bar into a ladder by atttaching another bar below the fixtures - top level is a fixed frontwash, bottom level is for focusing. Without knowing the full context of course difficult to say but don't be afraid to explore this sort of thing too as well as buying new toys! :)
  11. I did have some problems over the summer with the BMD micro convertors behaving erratically on different power supplies - on the individual PSUs that come in the box they were fine but putting them onto multi-way Anker USB power supplies gave us some faults that were very difficult to pin down - things not working depending on which order they were plugged in, different HDMI sources not working on the same convertor and so on. As there's no on-screen display or any real configuration options (which I see as a plus - it's a 'does what it says on the tin' product) it's difficult to tell the difference between the convertor not working, dead cables and so on. Once we swapped back onto individual supplies I think I recall all the problems vanished, so your millage may vary.
  12. To be fair to them, I had a power supply fault with one of their old outdoor fixtures a couple of years ago; they had no problems fixing and turning it round the next day.
  13. Tada! https://www.neutrik.co.uk/product/nc10fd-lx-b Back when these came out I asked Neutrik at a show what they were for, and they explicitly said CATx data and power. Annoyingly only solder buckets though, but I can see that getting a full 110 block onto it along with the power pins might be a challenge....
  14. Selling a twin LCD flightcase with a hinged lid - fits two 4:3 flatscreen monitors about up to 17" diagonal - or you could take the foam and partition out and do what you like with it. External dimensions aboeut 46x41x52cm. Looking for £25 - collection preferred from SO22 but could post at cost - likely about another £20-25 to post though I think. Photos: https://imgur.com/a/w99yyIT
  15. If there's nothing in your theatre's individual license, then there's no such regulation that I'm aware of. Like all computerised kit it's best if the server and switches are on a UPS to cover short brownouts and blips.
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