DrV

I've seen it once with a scroller connector (4pin XLR) and once with a really cheap and nasty audio lead (3pin XLR).

First you should check that you can actually see the phantom voltage between each core and the screen with nothing plugged in. Then, I assume that you've tried several different mics or DI boxes on the end. If all that's ok it must be something like a strained contact in an XLR somewhere. You might well get contact with a meter probe when checking continuity but an actual XLR plugged in might not make contact. To prove this you could get an XLR extension lead (male - female) or two, plug that/those into the ends of the offending cable and buzz out the cable using those. In other words check the cable without using meter probes on the offending cable itself, just on the ends of the extensions.

Well, that answers the question about the pinout then. Never occured to me that there'd be a crossover in there too!

Don't suppose you took a picture? It would be interesting to see (to me anyway 🤨) Dave

Yes, people do get hung up about termination of DMX - it's only 250kbaud over (usually) relatively short distances. However, just because something usually works doesn't mean that one shouldn't try to use the best practice from an engineering point of view. RS485 is designed as a multi-drop bus. Usually we drive it from one end and receive everywhere else so it never occurs to us that we could legitimately drive it from anywhere along the bus. Take an RDM fixture responding to a status request; that's sending a signal just like the desk does, with all the same physical layer characteristics. The signal goes off in both directions and anything on the bus that is interested can take note. Using a fixture as a y-split is not the same at all and would definitely be poor practice. Will it work? Usually yes but in the limiting case where you're running very long lines with transceivers which are at the very edge of their tolerance then maybe not. Engineering is all about reducing the potential for weaknesses at every possible step so that on the rare occasions when all the tolerances gang up against you the system as a whole continues to perform.

No, it shouldn't be terminated anywhere else except the ends. That's what "terminate" means. See page 14 of the TI 75176 datasheet for a picture.

But there aren't any branches if you just have one line plugged into each XLR - it's a single line with the desk in the middle so you should have a terminator at each end. However for relatively short lines where the propagation delay from one end to the other is small compared with the bit period it's not terribly important. There are people on here with a much deeper understanding of transmission line theory than I but I think I'm broadly correct. Dave

Well, I give up! There are too many unknowns. Don't suppose you can open it up and have a look? One thing I would say is that it's unlikely to have an isolating transformer as Ray shows but more likely an auto transformer (cheaper). However he has experience of installing such systems which I don't. If it is an autotransformer then I would suggest that the speaker itself is connected between T2 and T4. Clearly 100V into .013k would be a lot more than 25W! That also means the supplier doesn't know what they're talking about.

The supplier suggested T2 and T4 which would be 3k7 with the OP's figures. Assuming the d.p. error this is 370 ohms which gives 27W which is 25W within acceptable measurement errors

I'm not terribly experienced with 100V systems but I understand the basics. If you calculate the power based on the impedances shown in the table they come out correctly. So for 25W you would need 400ohms. Are you sure your decimal point is in the right place? The impedances you quote give you much lower powers. If you have indeed got 104 ohms 224 ohms and 474 ohms then the powers are more realistic.

I think sunray is right. But you don't need an impedance meter - just an ordinary ohmmeter will give you an adequate comparative reading. The resistances will be lower than those shown in the table but they should follow the same pattern, using the top terminal as common you should see increasing resistance as you work down the terminal block.

Is this what you need. It's got all the connections for the whole range Sorry, re-read your post - that's what you already have

The City Theatrical ShowBaby uses a male XLR with a single contact to tell the unit whether it's a transmitter or receiver. But unless you add some electronics it wouldn't be any use for this application.

I believe floors often creak because the nails holding down the boards have loosened and the creak is caused by wood sliding past the nail. You might recreate this by using screws which have a straight shank at the top (standard wood screws), screwed through holes which are considerably smaller than the screws. You then need to create the movement which would be by making the joists uneven. This would give room for the boards to move as they were walked on. Using short boards only 3 joists wide and making the middle joist the higher one would also help. The screws would need to be not quite tightened down. This is all surmise though - no experience other than my own poor quality DIY which creates just this effect!

On the mobile web page scroll right to the bottom of the page and click the "Follow" button then select how often you want to be informed.

The Rosco device is just an electronic slide. You need to insert it into a conventional luminaire. See the pic on the stagegear site Edit: I don't think it's even that - just seems to be a DMX controlled rotator

Like dog owners looking like their dogs, presenters grow to look like their mics!

Most electrolytic caps are rated for between 2000 and 10000 hours, albeit at maximum voltage and maximum temperature. Most switch mode PSUs have a 400V reservoir cap running at 340V. That's the weak point of many fixtures.

I contacted Chamsys support and although they didn't tell me exactly what I'd done wrong, it was sufficient for me to realise the error of my ways. In case anyone finds this on a search, the setting is not "wing 1 pb1" it should be "go selected playback". Apparently pb1 on a full size desk does not map to pb1 on a wing. BTW Support got back to me very quickly All sorted Dave

It's a genuine magicQ PC wing. The install was done a few months ago so it is a very recent version. I'll check precisely tonight. The remote trigger worked fine when it was plugged into the old windows system. I could reconnect it just to check the port hasn't failed but not this week. The switch connections and the link between the other two pins are still there (and tested) so there's nothing wrong with the external hardware. I agree that it doesn't sound like an OS issue with everything else on the wing working correctly. It's just that as far as I can see I've made all the setup changes needed, so didn't know where else to look. Was it you* who pointed me at the solution to the other problem I had (which was library related). Worryingly I can find neither the thread nor any notes I made at the time so if I had to reinstall I'd be back to square one. Thanks, Dave *edit: I've found it all and it was themadhippy to whom I owe the beer for the previous problem!

I've recently changed our lighting computer from an ageing WindowsXP system to a Debian Linux system and everything is working except the external trigger. We have a PC wing and I've always had an external GO button mounted on the followspot so that I can operate both. I've enabled the trigger in the settings/port menu and set it to trigger PB 1 but it's not working. It always worked with the old system and I've checked continuity of the button through to the mini DIN connector. I'm guessing it's a linux issue but don't know where to start. Can anyone help?

Gonna file that idea for future reference!

Sparks Theatrical Lighting used to have some but it's a long time ago. If they have, then tell them someone Super, Amazing, Fantastic mentioned them. It will be interesting to know if Paul remembers me!

Especially if it's got a blue casing - that must be absolutely ancient. The green ones have been around for at least 20 years! I resurrected a GSX last week, which had suffered Varta's disease but at least it was a green one.

Just had a quick search of the manual and there's no mention of "sound" or "audio" anywhere. Moreover the fixture does support setting things via RDM so it's clearly not the same issue as described in that other thread that I linked to. Sorry about the red herring. What desk are you using? Edit: Also, what other fixtures have you got on that DMX line and is it terminated correctly?