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KevinE

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    self employed
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    Kevin Edwards

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    Staffs UK
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    When not at work I play Hammond Tonewheel, restore 1930's valve radios and drive vintage cars.

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  1. you can break the thing open to count the stripes on the 'pot track'. It will tell you the number of pulses, (one stripe per pair) and of course the detents you can count by feeling them. The other thing which I suppose is obvious is getting the right shaft. Usually they're a d-type with a shoulder. Get the shoulder in the wrong place and the knob will either stick out, or sit down low and eventually after a few knob presses, will ground itself out at the bottom and you'll lose the switch action. It's all great fun isn't it.
  2. That's what I was thinking, although an internet search for the one fitted also gives 'sx300 woofer' but on the Bax Music retail site. I've emailed Bosch to see if they can advise.
  3. Got a client who's brought in a new-ish SX300 8R cab. The fault description is 'woofer torn up'. Ok - it isn't, and it plays fine to me. In fact the driver looks like new, its the later black basket with the foam gasket neoprene surround. Part number on the back is F.01U.188.438.19004 (no other markings on there). A quick test wih a meter shows its DC resistance as 3.9R - a bit low I'd have thought. A quick check on the back and it's definitely marked as an 8R cab and the low reading is also present on the speakons. I'm looking for advice. Does anyone know the DC resistance of this woofer? I think it's the right one - although the grille has one odd screw and the driver bolts were loose, as though someone has been here before. I don't want to return it with what turns out to be a partially burned coil....or overcharge for a needless recone. The client is not the end user so I can't approach them directly for elucidation.
  4. it will be a mechanical quadrature encoder. The thihgs to watch out for are as follows: 1. number of clicks (detents). Some encoders are 'smooth' and have no detents at all. Get one with too many and the circuit may see the pulses too quickly and refuse to move the figures, due to the way the anti-bounce circuitry works. 2. number of pulses. The pulses are a pair with a phase angle in between them, which is how the thing knows which way you're turning it. You can get a pair per detent, a pair per 1/2 detent, or 2 pulse pairs per detent. Get this wrong and the parameter you're changing will alter out of sync with the detents, not a huge issue but it can be annoying to use if you're altering something that must only go up or down one, for example. 3. Phasing. The pulse can change either on arrival at a detent, or half way between two. Far more common is to change half way between detents, but if it's the wrong type, the setting might randomly change up or down one even when you're not touching the control. (this scenario is rare). 4. Pulse direction (A leads or follows B). This is a common variation. This determines which way the setting will go depending on clock/anticlock rotation. Get the wrong type and turning the knob clockwise, for example, may result in the volume going down, and vice-versa. They're cheap enough - order one, and if it works first time, great! If not, try another 😃
  5. No harm changing them, but while they're out I would carefully check the PCB tracks. The sort of glue that is used on active speaker pcbs can liberate a corrosive substance over time which can rot the copper. Make sure you glue the new ones back in, use neutral cure high modulus silicone or similar fixative or they'll be rattling around at the bottom of the cabinet in a few week's time.
  6. these are part of the output filters, they're inductors in the class-d woofer output stage, as already suggested. The dark stuff is the glue that holds them to the board gone a bit dark. Inductors are marked in uH plus multiplier, so 220 is 22uH. rs wurth 22uH ferrite power inductor
  7. You've checked pretty much everything I would do myself, (loom/motor); sometimes the clearance of the blades is a little tight and altthough they look ok, they can touch (say) one of the other wheels but only when they're at a certain position, colour or gobo etc. I would make sure the blades are perfectly free in all positions of the other effects. The only bump stop that's important is the one used for reset, if the other is missing or worn, it's just to stop damage or noise during transit. Once the shutter has reset properly against one bump stop it shouldn't ever touch the other one, since the program knows how many steps it can safely take. As an aid in diagnosis I would write a little program to continuously rotate and exercise all the effects inclding the shutter and pan, keep the lamp off and see if there is any ticking or clanging at any point (notwithstanding if it crashes on the stops) that tells you the clearance is not right. ISTR having a leaky capacitor on one of the stepper drive ICs that controlled the torque to one of the effects, meaning the motor was not increasing its torque during a movement and reducing it during a static state (as they often should). I cant remember if it was a Robe or Coemar or similar but it was a tricky fault to find.
  8. Yes I've seem them used on mains (of dubious origin) but they seem to have very tiny cores and the 3-pin ones dont have a first to make, last to break earth, the pins are all the same length. The fact they are mostly used in SELV garden lighting is like using an XLR connector for mains! I don't recommend it! aliexpress cpc LEDJ DMX cable
  9. as well as fairy lights they're also used on outdoor decking lights (garden/pond lights etc). They're all moulded as a cable set so I doubt you could buy the connector seperately from what they're connected onto already. You can buy m-f extension cables in 2 and 3 way, with either flatted or keyed design. SELV of course.
  10. Certainly some of these chinese lights have a calibration mode, for setting things like the RGBW gain on each channel, max current etc, but accessing the engineers menus are usually well hidden for obvious reasons. A client of mine once imported a load of cheap cordless uplighters and one of them was experiencing short battery life. He emailed the OEM and they gave him the engineer access code so he could check the current calibration of each led (they were ok) and it turned out to be a duff cell..they sent a new pack and I fitted it for him. It was a very convoluted way to access the calibration involving setting a particular DMX address, going to a user-accessible menu item, (I forget, maybe mic sensitivity or something) and setting in a particular value, pressing and holding enter for 10 seconds..then you got access to the secret menu. Needless to say unless you can reverse engineer the code I doubt you'd stumble across the procedure by chance.
  11. I've just had a look at a few commercial DMX splitters/isolator diagrams and they all seem to be simple rs485 receiver > TTL > rs485 transmitter with each transmitter hooked to an opto and supplied with their own dc-dc converter, so in theory these should work, after all they're not analysing or buffering or manipulating the data in any way. I suppose there will always be the exception where some clever clogs designer has used a microcontroller to improve something or other.
  12. I've just had a single SOIC16 chip delivered from Farnell in a shoebox-sized carton.
  13. I did somethihg similar a few years ago where a client wanted 'cordless' par64 cans. (for effect, not for lighting a subject!). I fitted some 12V led lamps in place of the original holders, added a boost converter pcb (readily available from the usual sources) and ran them off a USB powerbank. This way they could be recharged quickly and safely with a system that the layman could understand.
  14. This unit from Thomann will allow you to save DMX sequences or scenes in real time from any other DMX controller. It will then just replay what you've saved under a set of push buttons. So long as you have something to create the show in the first place you'll be ok. Perfect for moving lights. https://www.thomann.de/gb/stairville_dr1_dmx_recorder_19_sd.htm
  15. Wonder if anyone recognizes this sky-tracker effect and can tell me something about it. It's marked 'Andi Sway' and nothing else. It has a fairly standard xenon double ended lamp inside and an ignitor next to it. In the base are 2 electronic ballasts. There are selector switches for 1kw, 2kw, 3kw and 4kw. Only the 2kW switch brings about any signs of life, and all it's doing is firing the ignitor, which can be seen in the lamp as a flashing/ticking. The fans in one of the ballasts run but the lamp does not maintain any sort of discharge. At first glance it looks like a typical chinese aliexpress special but seems too well built for that, particularly the internal wiring. I've only really dealt with the industry standard makes like Studio Due & Strong The owner has said the lamp is ok. Just before I go through the pain of removing the ballasts and finding I can't get (or find) a new one.....
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