DrV

A long shot but you could try warming up the hub in the middle of the wheel with e.g. a gas soldering iron in hot air gun mode. But don't overdo it!

I'd add to that, that you should use two levers (e.g. broad bladed screwdrivers) between the motor casing and the hub of the colour wheel. The levers need to be 180 degrees apart and try to apply force alternately in a rocking motion. I've also found that squirting a bit of isopropyl alcohol into the holes where the grub screws were helps.

Tom, I've re-sent the PM that seemed to go missing. It is worth pointing out that a tickle from a piece of equipment doesn't necessarily indicate a problem with that equipment itself, nor indeed with the general installation earthing. For example, if you have a good connection between your hand and a microphone connected to a bit of leaky equipment and you brush your arm against something which is well earthed, then you will feel the tickle on your arm rather than your hand. As Paul says above, it is a pretty trivial task to check with an A.C. voltmeter (a modern high-impedance digital meter, not one with a moving coil!) connected between a known good earth and anything you think may be causing a problem. Anything over a volt or so would suggest a problem. This is NOT of course an exhaustive test and MUST NOT be relied upon to verify safety. It would only be an indicator of where the problem might be. Beware of readings involving Class II devices (many wall warts and laptop PSUs and basically anything with a "double-insulated" symbol on it) as the maximum permitted leakage current is 250uA which you can just about feel with a damp hand and a light touch to earth. Dave

@Drv might be your man...! Thanks Ian, That's a whole day out plus from here so I'd need a little persuasion. Happy to look at the Betapacks back at base though if you can arrange transport to KT206JW. Send me a PM if I can help. Dave

Which is itself a VERY common cause of blown driver chips so don't replace a driver chip without checking.

Well it's either not moving or it is but is never seeing the limit switch so you start from there. If it's not moving (even if you wind it out from one end before starting up) then you're looking for a driver chip fault or a dodgy wire. If it is moving ok then you're looking for a faulty limit switch or a dodgy wire. It's been a long time but isn't the focus limit an actual microswitch rather than an optical or hall effect sensor? Could just have slipped or got a bit bent.

Thanks Tom. I'll pass that on Dave

Yes, one of the booking sites (theatremonkey.com) has two contradictory plans on the same page. All the others show the standard plan, hence the question.

Can anyone in the know tell me for _certain_ if the seating for 'Fiddler on the Roof' will have an aisle down the centre of the stalls. A friend is booking a whole row and has certain requirements for aisle seats. Most of the plans on the web show a solid block but one shows an aisle (thrust stage?) which would provide two extra aisle seats per row. He has had no joy from the ticketing people so is not sure what to believe. Thanks Dave

If you used the kl2 in conjunction with the "optional sliding bracket for M12 bolt" and put the kl2 and swr inside the bracket, the cable would be closer to the centre of gravity of the Sceptron which would help to reduce the droop you mentioned. Edit: I meant KL2-6.

The great thing about using an audio tie line to get DMX down to the stage is that you can use a dynamic mic (someone else's) as a signal tracer ☺

On the schematic the fuses are shown as F1 3.15AT and F2 2.00AT. Which one is blown?

IIRC the led on the 5volt rail will light with no power connected at all if you move the head around. The emf created by the pan and tilt motors is enough to turn it on.

If no-one with more experience of the units comes up with suggestions, you could try putting a picture of the PCB somewhere public and posting a link here. We might see something obvious. It seems likely that there would be a fuse but usually this would be a self resetting type (eg. polyswitch) Dave

Just a simple voltmeter will do. -ve probe on the shell of an aerial connector or on pin 1 of an audio XLR. +ve lead on the core (centre pin) of an aerial connector or on pin 2 or 3 of a mic lead. Nothing magic about phantom power. It's just d.c. Dave

I already have a board level device which happens to do this. It was designed to intercept a DMX stream and, under certain conditions, modify some channels. It's just a PCB with a DMX receiver and transmitter with a microcontroller in between. It also has a 5v regulator, some DIP switches (9) and a couple of buttons and LEDs. However, this board would be overkill for what you want and, because of where they are installed, it has no protection or isolation on the DMX lines. Adding a stripped down version of it into an existing splitter would be a doddle. All you'd need to do would be to pick up the received data after its opto and feed the unmodified stream (minus RDM packets) into just one of the existing output ports before its opto. The add-in PCB would need just one chip (maybe plus a regulator). Less than a square inch I reckon. One cut track in the splitter and a bit of soldering. Food for thought...

Check your PMs Dave

I would suggest going a little further and finding out whether the fault is in the PSU itself. You might be able to find someone locally who can repair it. Where in the world are you?

Been watching this thread go by and now I've suddenly realised I have the tech manual right here. Sorry! The supplies to the input channels are on the following pins 2 is 48V 3 is +15V 4 is -15V 5 and 6 are analogue ground Edit: Just had a slightly closer look and the Mic preamps use +48v unlike the stereo inputs. (This is regardless of whether you are using phantom power). So, this is the big difference between the mono and stereo inputs. To confirm that the 48v is the problem, try inputting a line level signal at a Mic insert Jack and you should get some output. Dave

Crumbs... that brings back memories - double sided non pth boards and having to solder all those little link wires through the board. But that was for PDP11 interfaces in the late 70s - I digress. What we need is really clear pics of the left hand end of each board - clear enough to read chip numbers if possible. What are the three components in the lower left corner of the 3 triac boards? And if they are little toggle switches what are their positions? No - just spotted the addresses! There is a row of 6 pin pairs just above the ribbon cable on each triac board and they are currently set to 1 2 and 3 respectively. If you move those to 4 5 and 6 I bet you'll find that works

There will be some configuration switches somewhere either on the front or rear panel of the units or possibly inside them. You will need to set them to 18 (or perhaps 17) on the second dimmer. If you find them but can't work out what to do then put a photo of them on a website and post a link to it here. Do they have a numeric display on them of any sort? Dave

Not likely to be triacs if the pre-heat is working correctly.

Haven't got a schematic but from a couple of photos of the PCB it appears to use both H11A1 and IS608 optos. The first is a transistor output type and the second is an opto triac. Can't see how many of each type (which would give a clue to where they are in the circuit) but I wouldn't be surprised if the IS608 is one per channel and the H11A1 is one per phase in the ramp circuit. The up side is that on my photo they are on sockets which makes on-site repair a lot easier. I think the last one of these I repaired had broken tracks around the input DIN connector and I think the way these are wired means that they are in two sets of 3. Just occurred to me - they haven't moved the DIN connectors around have they? I think it's possible to arrange this so that only half the channels work. All a bit vague I'm afraid as it's a long time since I fixed one! Dave

Looking at the spelling of 'audible' and some other errors it looks as though they had the work experience kid on the Notices desk that week!

As it happens I've just made up a dimmer to control 12 independently dimmed sets of a.c. fairy lights for an amDram show. I've chopped the sets up into 12 volt sections. You identify sections by finding the place where there are only two wires between adjacent LEDs rather than three. Each section is 3.1V so 4 sections makes a nominal 12V length. I'm then driving them through L298 stepper motor power modules. One output of an Arduino Mega provides a square wave at about 1kHz and this drives the direction inputs of all the modules and the enable inputs come from the rest of the PWM outputs. The dimming is rubbish at the bottom end, as expected, because the PWM outputs are only 8bit, but otherwise it works fine. The 12V supply has been tweaked up very slightly to compensate for the slight forward drop in the modules. You do need to monitor the current when setting it as there are no series resistors. Each L298 has two H-bridges so can drive two sets and they were only about £1.50 online. The PWM frequency for the enable pins is set higher than the default at 3kHz. Dave