Hilary Watts

I've got a Behringer LC2412 which I bought in 2005 before I had any LED fixtures. It was excellent value at the time and I still use it regularly for small events with a limited number of lights which just require a few presets fading up and down. However, it has some idiosyncracies, it certainly isn't suitable for moving lights and as most LED fixtures require 4 or more DMX channels the fact that it can only handle 24 channels in all is extremely limiting. There is a reason why the behringer and showtec type desks are a fraction of the price of a 'proper' desk .....

Thanks for the link. I've never met John although I did exchange a couple of emails with him a few years ago about a possibly defunct Neutron hazer.... It will be interesting to follow his progress.

I've had one of these desks for over 10 years and have never come across this particular issue so I too would think it's a faulty lighting unit or faulty cable. The only (minor) problem I have had is that when using the submaster/memory faders the output stays at about 3- 5% even when the channel fader is at zero. This is hardly noticeable with tungsten lamps but the LEDs to which I have access still produce some light output. It doesn't cause a problem (the master fader can be used for full blackouts) so I've learned to live with it.

Was it possibly Dance Floor Tape?

I've had 3 of the stageline boxes for about 5 or 6 years. They are transformer coupled and have the switchable pad and ground lift as you describe. They haven't had a lot of wear and tear but seem fairly rugged and the sound quality is perfectly ok.

We don't know the make or pinout of your demux. However the 25 pin D connector will have at least one (and possibly more) pins connected to ground and then a pin with a varying voltage for each channel. You need to identify which are the ground pin or pins (perhaps pin 1 according to the final conclusion of this thread ) and then connect one of them to Pin 2 on one of the 8 pin din plugs. This will give the ground connection. Next solder to pin 3 on the din plug a piece of insulated wire long enough to reach the back of the D connector when it is plugged in to the demux. Leave the casing off the D connector and set channel 1 of your DMX controller to say 50% (which will give an output of around 5 volts from the demux). If you then touch the other end of the piece of insulated wire to each of the D connector pins in turn you will be able to establish which is channel 1 by the fact that the dimmer will turn on. Try Pin 13 to start with as the pinout may follow that specified by Paul IDF in his post on December 12th in the thread referred to above, However, ignore his references to the Din pins as he is talking about the Strand pinout, not the Pulsar. Once you have established which is the channel 1 output on the D connector then set channel 2 at 50% and repeat the process until you have identified the output pins for all the other channels.

Was it a Pageant Light? I've never seen one in the flesh so I don't know the actual size but it more or less fits your description. I know they sometimes had a set of rings on the front to reduce spill. e2a Sorry -ignore the above. I'd misread the title of the post as 'an OLD stage light'...... I don't think many rock designers use pageant lights.......!

Sorry, it's taken a little while to take up your suggestion but we've now done that and pressing the start button produces a consistent stream of sparks across the gap (it was fairly easy to set it up safely by disconnecting the lampholder and setting up the copper wires on the terminals attached to the circuit board). This seems to confirm our theory that the (new) lamp was faulty. We're presently waiting to hear from the supplier.

Some years ago I bought a couple of Ben Suffolk's units which can be found on this page; they were easy to fit and the dimmers are still in use.

If you look on this page under 'Miscellaneous' and then 'Setting up a Backup Computer' there are instructions as to how to set up a second computer running in sync with the primary computer so that if the primary fails then the audio feed can be switched over to the backup - there could be a physical switch involved to select the output from either the primary or secondary computer or alternatively you could just route them to separate inputs on a mixing desk and use the channel faders to select one or other computer as the source. The main point is that as the computers are running in sync and receiving the same cues then at any one time both will be at exactly the same point in the cue list and/or track and you can switch over from the primary to the secondary (in the middle of an audio track if necessary) so that audio is restored within seconds the operator realising that the first has failed. I've referred you to the SCS page as this is a program I'm familiar with but no doubt other sound programs can acheive the same thing, possibly with more sophisticated features. Happily however I've never had a computer fail mid-show so I can't claim any personal experience in this respect!

Thanks - that's an interesting suggestion. Strangely, when we had the insides opened up at the weekend we did discuss (in jest) the possibility of powering a Jacobs Ladder from the starter circuit. I think we have two early models. There's no interlock switch and there's a simple fuseholder on the back panel - no mcb. The control circuitry including the igniter coil is all in a shallow metal tray under the lamp housing and it simply unscrews for access. I'm puzzled by your reference to the big capacitors in the ballast. The circuit diagram simply shows a .005uf capacitor in parallel with the coil(s) and in the two ballasts I have opened up it is small ceramic disc like this which measures as expected on a multimeter and there is no sign of any deterioration. Finally, I am happy to confirm that if I kill myself I won't come blubbing to you .... although I can't say the same for my nearest and dearest!

Thanks for all the replies. To save time for people who don't want all the details I'll say in brief that the conclusion we've come to is that the new lamp is faulty. For those who are interested a friend and I had another good look at the situation over the weekend. We double checked all the internal wiring and the action of the starter relay in making and breaking the circuit to the high voltage coil. I also had a look at the wiring to the plug and socket connecting the ballast and this was all in good order. We have two spotlights which have both worked without problems in the past; they and their ballasts appear identical but at some point (before our theatre acquired them) some one has replaced the original ballast connector plug and socket on one of them with 16A CEE connectors so it's impossible to mix up the ballasts. The lead from the starter coil on the unit we dismantled has heavy duty insulation unlike the rest of the wiring and there is no sign on arcing or tracking either in the lantern gear tray or in the ballast . Thanks for the voltstick suggestion - that confirmed there is a voltage appearing at output of the starter coil and it appeared to be significantly higher than mains voltage (it's possible to do a direct comparison as one of the terminals on the terminal strip to which the lamp is connected is normally connected via the ballast to mains live - however if the ballast is unplugged then this simply leaves the other terminal which receives the higher violtage from the starter coil when the 'Start' switch is pressed). I had wondered about the difference between the original CSI lamp and the later CID lamp but the GE Lighting catalogue seems to show the same technical data for both apart from the fact that as mentioned the CID lamp has a lower output in lumens and none of the literature I've found mentions any incompatibility. Finally we did look up the lens tube (after opening the iris!) and there was no sign of an arc when the starter switch was pressed. This might suggest the absence of a sufficiently high voltage but the most compelling factor is that the blemish shown in the photo attached to my original post appears to be slightly worse than at first thought and on close inspection there seems to be a flaw or possibly even a hole next to the electrode at the junction of the glass and the ceramic base. This and the fact that the lamp shows no sign of striking in either lantern leads us to the conclusion that we need to try a second lamp before doing anything else. We're sending the lamp back in the hope we can get a replacement. I'll report on the eventual outcome and in the meantime thanks to all for accompanying us on a trip down memory lane.....

Yes, I forgot to mention but we do get the buzz so the starter relay is clearly kicking in.

Our theatre has two Patt 765 follow spots. They have not been used for the last two years as a result of the pandemic (and may not have been used for some time before that) and on inspection neither has a lamp in it. We have obtained a new lamp from a reputable supplier but it fails to strike in either of the follow spots. I have downloaded the technical handbook from the Theatrecrafts website and have checked the values of the components of one of the units (including the choke which is in a separate enclosure) all of which are within spec and appear undamaged. The internal wiring is in good order. The relay which provides the starting pulse is vibrating but I don’t have the equipment to check whether the 10Kv starting pulse is actually being generated. My questions are: 1. How quickly would you expect the lamp to strike after pressing the ‘Start’ switch (ours are the older model 765 with manual start switches – the later models had a relay- actuated start once they were turned on)? The manual advises against letting the starter run for more than five seconds and suggests a number of shorter duration attempts but doesn’t say what would be a ‘reasonable number’ before concluding that something is defective. 2. In the experience of members is it likely that the new lamp which we have bought is defective? I have attached a photo which shows a small blemish on the lamp but I don’t know whether this is significant or whether there was generally a high failure rate for such lamps.. 3. Does anyone have any suggestions as to further fault-finding steps in the absence of high voltage test equipment? We don’t have an alternative lamp to try and are reluctant to buy another unless we know there is a reasonable chance of getting the units going. (I thought I might replace the 3 capacitors and 2 resistors on the basis that while they appear undamaged and produce the right readings on a cheap multimeter they may react in a different way at mains voltage or higher.)

Sorry for the delay in replying. However I can confirm it is a plastic bodied single circuit unit as shown here.

Sorry, I can't help. I bought the last one Polar Audio had in stock in 2017 or 2018 and did the repair but the same unit was dropped soon afterwards and came back to me. It's currently awaiting repair again but I haven't found a supplier for the pot (I put it on one side during lockdown and forgot about it). I haven't been able to find any adverts for a current ASL stage intercom system and it looks as if the company was taken over in 2016 by Riedel Communications which seems to produce rather more upmarket wireless products. You've prompted me to have another look at the beltpack - I'll let you know if I can source a suitable pot.

You say that in the rehearsal room you had fun, and you thought the production was good. There also seems to be some feeling of loyalty among the company. In addition to the rewrites is it possible to use the time before your next performance three days hence to devise some lighting and sound cues and then have a 'proper' tech run and dress rehearsal. This might put the actors at their ease and improve the cast's morale and make the rest of the run bearable for everyone involved. You will have learned a lesson and in the future might at least be able to look back on the production with a wry smile

You will need to amplify the mic signal to line level in order to in order to use the line input since the output of the mic on its own will be too low. It's not clear from your post if the mic kit includes an amplifier but if not then that's the likely problem

The wiring in your picture (ie four wires plus earth) looks similar to that of a projection screen motor which I've recently been investigating. In my case the two grey wires go to one end of the motor windings. They are joined together outside the motor and connected to mains neutral . The red wire and the blue wire are joined to the other end of the motor windings and a capacitor is connected between them. The live feed is then applied to red or blue, depending on the direction of the rotation required (eg for 'Up' the red wire is connected to live and this then feeds the red winding directly and the blue winding via the capacitor. For 'Down' the blue is connected to live which then feeds the blue winding directly and the red via the capacitor.). In my case one of the motor windings has failed with the result that when a button is pressed then occasionally the motor starts running in a random direction but usually it fails to start at all. I'm currently looking for a replacement...... Ths may or may not be relevant in the case of a tubular ripple (I don't know if it's possible to change the direction of rotation on them). However if the wiring arrangement is similar to my screen motor then the capacitor in the photo is not the 'start' capacitor as the one in the photo is apparently connected to the two grey wires (and in series with the mains neutral?) rather than between the red and blue live feeds. It could however be there to drop the incoming voltage for the motor as suggested by Richard.

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You're a true gent Paul - although I would love to know what the post said! Hilary

You could possibly try Sabre Technology. Tim Mitchell (Timsabre) is a regular contributor to this forum. Hilary

All the best for your new role - as others have said we've enjoyed your contributions from down under so do keep up your membership of the forum! Don't be put off by Ynot's post ; my daughter worked for Marks and Spencer almost from leaving school, at first on the shop floor and then in the HR department. She was made redundant at age 36 and decided to train as a pimary teacher (despite dire warnings from my wife, who had recently retired from her 40 year career as an infant teacher!). My daughter's now been teaching for about 5 years and thoroughly enjoys it even with the added challenges of the current pandemic. If it's what you want to do then go for it! Hilary

It looks ok to me apart from the heater element (the model I have seen has the straight version of the element) but as has been pointed out yours may be an earlier version. Have you fired it up? I spent several hours trying to find a fault on one and after discussions with LeMaitre replaced the fluid pump which did not seem to be working. The machine still did not produce haze however, just odd wisps of smoke when it was started. I then had the bright idea of substituting the fluid bottle with a bottle of proper LeMaitre haze fluid, after which the machine worked perfectly. I've no idea who had used it last but it seems they had topped up the bottle with ordinary smoke fluid......

I made one for Sennheiser mics some time ago. So far as I can remember it's just a box witha minjack input with 2 AA batteries providing the power to the mic. There's then a capacitor to block the DC on the output which is a male XLR socket. I don't know if it's the 'correct' way to do it but it works. I'll have a look when I get home. Alternatively something like this might do the trick although at present I haven't been able to find a version with a Shure connector and I don't know if the voltage required by the mic is the same. However, the cheap cpc type headsets seem to be available with a variety of connectors to fit the major brands, which suggests that the voltage supplied by the beltpacks is the same.or alternatively that a range of voltages is acceptable.