Tempus 10Amp/5 Dimmer

[walkingjoke]

Hello,

 

The College Theatre I have come to work at has an extremely dated setup which is in need of a complete strip down and replacement.Unfortunatly before the powers that be will release the large amounts of money needed to do this I need to prove to them that the current setup shouldnt just, and probably cant be repaired.

 

We are currently running 4 x 6 way 10A/5 Tempus dimmers through a demux into a Frog desk. The problem we have is that two of these dimmers will trip after maybe half an hours use.

 

So, the question is.. does anyone know where might be able to repair these relics? or even if it is possible to obtain parts anymore?

 

Any help on this subject will be appreciated.

 

cheers

[Ynot]

You MAY be able to source generic parts for the electronics within the Tempus units, but any actual Strand spares are going to be like the droppings of the proverbial equine seesaw.

 

I'd personally point the bursar at the fact that Strand no longer exist in any way as they were and that the Tempus range was discontinued a decade or two ago.

[boatman]

.

So, the question is.. does anyone know where might be able to repair these relics? or even if it is possible to obtain parts anymore?

.

 

It would help us all to give you better advice if you put your location into your profile. You may get some joy from some of the longer term lighting suppliers such as Northern Light in Edinburgh who were Strand dealers 20 odd years ago and may still have the neccessary technical manuals. However that may be too far away from you to be of any help.

[tony g]

Having fixed quite a few tempus dimmer racks in my time I can say for sure that there is nothing within them that can't either be got from RS or modified to take something from RS, any electronic engineer worth his fee can fix these as they are pretty basic - a willing TV repair man would be more than competent, or even the electronics department in your college. Thing will be the cost, I purchased 2 DMX controlled fan cooled, flight cased strand dimmers that were only 6 months old for £500 the pair (no desk) and you can get a new standard dimmer for not much more and I can easily see a repairer charging a couple of hundred to sort them out.

 

Incidently Stagecraft Technical Services in salisbury had some fully working Tempus racks for sale s/h if you wanted to replace like for like - personallt I'd get someone to condem the ones you've got and gets some new kit as these 20+ year old models are nearing the end of thir practical service life and will end up proving unreliable

[oilyspark]

I agree that there is merit in replacing the dimmers, but wouldn't go so far as to call them relics. Yes, if you can use the opportunity to upgrade to digital dimmers, then why not indeed - no adjustment needed, better curves, etc... But we routinely maintain all sorts of electronics 2-3 times older than Tempus racks and the chances are that the old stuff will still be working when today's products are long gone.

 

You don't say what is tripping. The MCBs? RCD? Most dimmer problems won't cause anything to trip, just lack of dimming. Please tell us more about the fault...

 

Lucien (who can occasionally be persuaded to fix Tempuses)

[Pattern123]

They can certainly be repaired, although it sounds more like you may be overloading the supply - is it 32 Amp per dimmer perchance? Any major theatrical supplier; While Light, Stage Electrics, Northern Light, Hawthorn, etc, should be able to service & repair these for you, but it will cost a few quid. SLX have an offer currently on 2 new Betapacks for £399 + VAT, assuming they haven't sold out of the offer, surely a better bet

[J Pearce]

If its an RCD tripping it could well be an aging capacitor somewhere in the earth path that is warming up then leaking too much current to earth for the RCD to be happy with.

[tony g]

I agree that there is merit in replacing the dimmers, but wouldn't go so far as to call them relics. Yes, if you can use the opportunity to upgrade to digital dimmers, then why not indeed - no adjustment needed, better curves, etc... But we routinely maintain all sorts of electronics 2-3 times older than Tempus racks and the chances are that the old stuff will still be working when today's products are long gone.

 

You don't say what is tripping. The MCBs? RCD? Most dimmer problems won't cause anything to trip, just lack of dimming. Please tell us more about the fault...

 

Lucien (who can occasionally be persuaded to fix Tempuses)

 

Lucien makes a good point re-the quality of build in these older products and the fact that they are designed around standard parts that are still pretty much available without problems, you will in all likelihood still be able to get bits for tempus racks when newer units components are no longer available, I'd still be tempted to try and get some new ones though (why not when you have the chance), then keep the tempus units and get them repaired for spare/travelling use.

 

But again as lucien says tell us more about the fault, it sounds like you are overloading the supply to me or possibly something is breaking down insulation wise, tell us about the following

 

Total load youve got running

Incoming supply, rating in A and cable size if poss

Rating of the thing thats tripping Amps if its an MCB, A & mA if its an RCD/RCBO

also how far away is the trip, if its a long way and the dimmer is pulling a heavy load the cable may not be sufficient for the distance (resistance increases with distance driving volts down and current up then pop, it trips - or catches fire :blink: )

[swampman]

If its an RCD tripping it could well be an aging capacitor somewhere in the earth path that is warming up then leaking too much current to earth for the RCD to be happy with.

 

If memory serves me there is a PCB on the cover where your plug sockets are: each channels live output is filtered by two capacitors to earth and neutral. There is also a green neon earth test indicator wired in there.

Spain was in advance of the UK with RCD (earth leakage protection) - much needed because the earth wiring was often faulty or not even connected, historically - and these dimmers were (and still are) reliable but when the capacitors were imbalanced the protections would trip, especially on connection.

You can test to see if components on this board are faulty by disconnecting it and running a load till the units are warm - if they do not trip you have narrowed down the area to where the problem may be. If they continue to trip a filter choke or thyristor may be leaking.

I reccomend you do NOT use without the filter board as it controls switching noise, induction problems etc.

[Dmills]

resistance increases with distance driving volts down and current up then pop, it trips - or catches fire :blink: )

 

Where, prey tell is the constant power load that would be required?

For something like a simple dimmer driving a TH lamp, less volts = less current, not MORE!

 

If it was a switchmode power supply or a induction motor or electronic lamp ballast or something then things would be different, but for general stage lighting, less volts = less current = dimmer bulbs!

 

If I wanted to fix them, I would start by checking breaker ratings, then (assuming it is an RCD that is tripping and not a MCB) look at the RFI suppression caps (These dimmers were known to have a bit of a tendency to trip RCDs), but if you can get modern racks then why not?

 

Regards, Dan.

[tony g]

The additional resistance is created within the cable if it is undersized, if say you had a 2.5 cable feeding this dimmer and a full load on it the cble would be undersized for the job, the cables own resistance causes it to warm up, increasing its resistance still further and drawing more current - as the current rises the delivered voltage falls hence you light dims (think about the deliberate wiring arrangement used in US prisons in the past where the electric chair was wired into the lighting circuits!), but the current still rises and cooks your cable.

 

This is a common problem for example householders fit an electric cooker or shower in place of an existing one, but fit one that is too big for the rating of the supply cable, a 1000W stage lamp is in effect exactly the same as a cooker ring, its simply a resistive load, the dimmer itself is simply a control, the load is calculated by the number of channels X max wattage on each to determine what cable you need - if you have a long cable run you need to size up to compensate for the cables own resistance

[adam2]

The additional resistance is created within the cable if it is undersized, if say you had a 2.5 cable feeding this dimmer and a full load on it the cble would be undersized for the job, the cables own resistance causes it to warm up, increasing its resistance still further and drawing more current - as the current rises the delivered voltage falls hence you light dims (think about the deliberate wiring arrangement used in US prisons in the past where the electric chair was wired into the lighting circuits!), but the current still rises and cooks your cable.

 

This is a common problem for example householders fit an electric cooker or shower in place of an existing one, but fit one that is too big for the rating of the supply cable, a 1000W stage lamp is in effect exactly the same as a cooker ring, its simply a resistive load, the dimmer itself is simply a control, the load is calculated by the number of channels X max wattage on each to determine what cable you need - if you have a long cable run you need to size up to compensate for the cables own resistance

 

You are mistaken in this regard.

With a load consisting of incandescent lamps, any reduction in voltage due to undersized of excessivly long cables will result in less current and not more.

This is not simply my opinion, but is an observed physical fact that may be confirmed by a simple experiment*.

 

Use of undersized cables can certainly be a fire risk, but that is because the load exceeds the cable rating, not because the undersized cable has increased the current.

For example consider a bank of lamps that draw 30 amps when wired with the correct cable.

Now connect the same lamps to the same supply but with undersized cable, this will result in a lower voltage at the lamps, and LESS current, not more. There would of course be a posible fire risk, but no way is the current going to increase beyond the original 30 amps.

 

Long runs of cable often have to be increased in size in order to limit voltage drop, this is done to ensure that voltage at the load is sufficient for proper operation. Not because the current has increased.

For example consider a cable rated at 30 amps and carrying 25 amps, on a run of 10M the voltage drop will be insignificant.

If however the run is increased to 200M then the voltage drop will be significant, but no way will the original 25 amps worth of incandescent lamps now draw more than 25 amps.

The voltage at the lamps will be reduced, the current will be less than 25 amps, and the lamps will be dimmer.

 

*If in doubt try the experiment !

Obtain a large incandescent lamp load such as a couple of 1KW lanterns.

Plug into the mains via a plug in power and energy monitor set to read amps, the reading should be a bit over 8 amps.

Now connect the same lanterns to the same mains supply but via a number of long extension leads. This will reduce the voltage at the lanterns, which will be dimmer, perhaps noticably so.

The measured current will be less and not more. (presuming that the mains voltage did not alter between taking the readings, if the mains voltage fluctuates a lot, then a number of readings should be taken)

 

Alternatively try a similar experiment at a safe voltage. Connect a 12 volt lamp to a 12 volt battery and measure the current. The extend the wires so that the lamp is dimmer and again measure the current, it will be less and not more.

[walkingjoke]

Cheers for all your comments.

 

I am no sparky but have done my best to gather more info on the fault. It seems that the trip occurs in the MCB. Unfortunatley our setup is so messy there are various trip switches (all wrongly labelled) linking into one another. I think its a result of the college attempting to cut costs by simply adding on bits and pieces over 30 or so years to meet regs' rather than to do the job properley for a one off cost. I've had stage lx, white light and custom group have a good laugh when theyve been round to quote for update.

 

I have bought up the fact with the powers that be that Strand went bust and the tempus was discontinued but I need hard evidence that we cant just fix the exisitng dimmers for a much cheaper cost. but it doesnt look like I will get it as it appears general parts can often do the job when fixing the tempus'.

 

The problem with just buying betapax is that all of our circuits are 5A. and the way of the world today is 15A. I have been told it can be solved by downrating something in the fuse box, but to me this seems too much like the colleges attitude to just bodge it together cheap as poss and I strongly believe in doing a job and doing it properley. So therefore in the upgrade I have had a new 15amp wired lx grid priced.hence the resistance met by the powers that be. Any view on this problem would be appreciated.

 

 

With the whole setup being design and fitted for 5A that may give you a clue to the cable size.

 

Apologies if I have missed any of your Q's.

 

Thank you all again for your help.

[thetechguru]

The Strand distributor in Scotland, Audio Light Systems, have stock of working tempus/permus modules.

 

How many would you like?

[tony g]

Cheers for all your comments.

 

I am no sparky but have done my best to gather more info on the fault. It seems that the trip occurs in the MCB. Unfortunatley our setup is so messy there are various trip switches (all wrongly labelled) linking into one another. I think its a result of the college attempting to cut costs by simply adding on bits and pieces over 30 or so years to meet regs' rather than to do the job properley for a one off cost. I've had stage lx, white light and custom group have a good laugh when theyve been round to quote for update.

 

I have bought up the fact with the powers that be that Strand went bust and the tempus was discontinued but I need hard evidence that we cant just fix the exisitng dimmers for a much cheaper cost. but it doesnt look like I will get it as it appears general parts can often do the job when fixing the tempus'.

 

The problem with just buying betapax is that all of our circuits are 5A. and the way of the world today is 15A. I have been told it can be solved by downrating something in the fuse box, but to me this seems too much like the colleges attitude to just bodge it together cheap as poss and I strongly believe in doing a job and doing it properley. So therefore in the upgrade I have had a new 15amp wired lx grid priced.hence the resistance met by the powers that be. Any view on this problem would be appreciated.

 

 

With the whole setup being design and fitted for 5A that may give you a clue to the cable size.

 

Apologies if I have missed any of your Q's.

 

Thank you all again for your help.

 

The fact that you are tripping an MCB points at an overload, this could be caused by any one of a number of things and without seeing the instal I wouldn't want to try and give a diagnosis. It is possible to upgrade existing 5A systems to use 15A plugtops, you can simply cut off the 5A plugs at the dimmer end and fit 15A plugs, this will work fine but would be frowned upon due to a risk of overloading - this procedure has been done in many venues as 5A dimmers have become impossible to purchase new.

 

A better solution would be to terminate all the circuits by way of a fuse holder, either in an unswitched spur box or a custom built panel, these holders would be fused down to 5amp allowing the patch leads to have 15amp plugs.

 

Crabtree still make a 15amp plug with a 5amp fuse, predominantly for the South African export market but they are obtainable here and would do the same as the above.

 

It would also be worth checking out the wiring of your grid, you may find the internal wiring will already support 15 amp, on the other hand you may find a host of nasties including common neutrals and asbestos, although neither has to condemn an installation it could be used as a strong argument to replace it.

 

I would get a reputable stage electrical specialists in to have a looksee and write a report on its condition, this will show you and the management where all the faults are. Best to go for an NICEIC registered firm purely because the vast majority of LEAs require specifically registration with this body although no law forces any company to be registered with them (check what your college would require with your estates manager)