Help Needed with Strand House Light Dimmer

Measure one of the outputs controlling a stage light dimmer, and you'll know what it's capable of.

Even if it is 0-15V, it might be close enough. Adjust a house light control to 15V and see what it looks like.
 
So essentially connecting the 18v to that board will just end up with less dimming? Or everything partly dimmed all the time? We're essentially losing the top end of the dimming capability?
PLEASE do not take offense but some of the assumptions you are making and questions you're asking are making me unsure
you understand how dimming systems work but of course that's probably why you are here!
You are not connecting 18 volts to the demultiplexer board... the demultiplexer board is sending 18v to the dimmers!
If you don"t feel comfortable working on this equipment, please call in a technician who is.

On the diagram I provided earlier in this thread, the "signal flow" goes from top to bottom, so the control voltage goes FROM a console or demultiplexer TO a dimmer. Zero control voltage tells the dimmer to not output AC voltage to a circuit/fixture; 15 or 18 vdc tells the dimmer to output full AC voltage to the circuit/fixture. IF the control voltage for full output of the dimmer is indeed 18v, 15v will tell the dimmer to output slightly less than full voltage to the circuit/fixture.

The first issue is the 18 volts. This is an odd but not unrealistic number.
As @FMEng has been saying, you need to use your meter. Set it to the DC Volts mode with a range of 20 volts or higher.
To find the actual control voltage to the dimmers, take a reading on the 48-channel demultiplexer circuit board by placing the negative (black) lead on one of the two COM terminals on connector J1 and the positive lead (red) on an easily accessible output terminal of connector J4 or J5. Slowly bring up the fader on your main console that corresponds to this number terminal and see if the meter slowly goes from zero to 15 (or 18) volts as you move the channel fader to full. If the meter needle tries to go below zero or if a digital meter shows a minus sign, you may have a negative control voltage!

Assuming this goes as expected, you should then do the same on the houselight control system.
BUT, there may be extra wires with other voltages in this system that operate "take control" relays or light up fader scales or buttons. Please post some photos of terminal blocks / houselight control wiring before trying to measure this.
And don't get in over your head so you're around to report back!
 
PLEASE do not take offense but some of the assumptions you are making and questions you're asking are making me unsure
you understand how dimming systems work but of course that's probably why you are here!
You are not connecting 18 volts to the demultiplexer board... the demultiplexer board is sending 18v to the dimmers!
If you don"t feel comfortable working on this equipment, please call in a technician who is.

On the diagram I provided earlier in this thread, the "signal flow" goes from top to bottom, so the control voltage goes FROM a console or demultiplexer TO a dimmer. Zero control voltage tells the dimmer to not output AC voltage to a circuit/fixture; 15 or 18 vdc tells the dimmer to output full AC voltage to the circuit/fixture. IF the control voltage for full output of the dimmer is indeed 18v, 15v will tell the dimmer to output slightly less than full voltage to the circuit/fixture.

The first issue is the 18 volts. This is an odd but not unrealistic number.
As @FMEng has been saying, you need to use your meter. Set it to the DC Volts mode with a range of 20 volts or higher.
To find the actual control voltage to the dimmers, take a reading on the 48-channel demultiplexer circuit board by placing the negative (black) lead on one of the two COM terminals on connector J1 and the positive lead (red) on an easily accessible output terminal of connector J4 or J5. Slowly bring up the fader on your main console that corresponds to this number terminal and see if the meter slowly goes from zero to 15 (or 18) volts as you move the channel fader to full. If the meter needle tries to go below zero or if a digital meter shows a minus sign, you may have a negative control voltage!

Assuming this goes as expected, you should then do the same on the houselight control system.
BUT, there may be extra wires with other voltages in this system that operate "take control" relays or light up fader scales or buttons. Please post some photos of terminal blocks / houselight control wiring before trying to measure this.
And don't get in over your head so you're around to report back!
Well, it looks like all of us are way off base on the control voltage except for @RonHebbard. Those dimmers want
0 to -10vdc. It is a negative voltage by the way Ron!
If you compare the OP's excellent photo of the demultiplexer board to the LCMD-48 Rev6 configuration sheet I posted earlier, one can plainly see that it is configured for 0-10vdc NEGATIVE output.

So, @crippit, the 18v you are measuring is surely a supply voltage or "take control" line to your remote stations and NOT the dimmer control line. This is why if you need any more help, we must have similarly detailed
photos of ALL of the houselight system control wiring!

LCDM-48r6.png
 
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All the Strand gear I have ever seen, a lot, is 10v control but will work on less, but this does not matter as all the Strand dimmers have trimming on the dimmers, which is just as well as they tend to drift around with age, they are wired -10v but most can work +10 by reversing the control wires on each module.
 
All the Strand gear I have ever seen, a lot, is 10v control but will work on less, but this does not matter as all the Strand dimmers have trimming on the dimmers, which is just as well as they tend to drift around with age, they are wired -10v but most can work +10 by reversing the control wires on each module.
Replacing the normal (~270 degree / open dirt collecting) trim potentiometers with small, sealed plastic, 10 turn, Bourns potentiometers then housing the Bourns pots in a Bourns, slip-on housing providing a tiny / tapered / funnel-like opening on one end for the insertion of a ~3/32" slot screw driver added years to the service life (and only annual trimming if you were REALLY picky) to 36 used JTM's ( A 24 dimmer wall-hung cabinet with a 12 dimmer wall-hung cabinet next to it) installed in Burlington, Ontario's amateur theatre in the mid 1980's through the early 1990's.

Parts cost for the Bourns 10 turns & Bourns' slip on housings was approximately $4 (Canadian dollars) per trimmer; 1 high + 1 low = $8 per dimmer.
The JTM's were eventually retired and replaced with four of Johnson Systems 24 dimmer wall hung racks for a total of 96 (1.3 KW if my memory is correct) dimmers.
Associates tell me the racks are in service / operating flawlessly to the nonce, or would be if the theatre wasn't moth-balled due to Corona chaos.
Think POSITIVE!!
Toodleoo!
Ron Hebbard
 
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Thanks everyone for your replies. I think we're actually going to look at removing the whole system and replacing it. Does anyone have any recommendations as to what to replace it with?

I think for now the house lighting will remain controlled by the JTM's but we'll look at a way to demultiplex the control from the existing system and link that through to DMX. We found someone who had worked on our system, and it turns out they had trimmed the cards to the point that Strand refused to service the units any longer. We also have at least 1/3 of the dimmers which no longer function due to shorts (which killed the dimmer cards).

At this point we're going to bring in an expert, if you are interested I can continue to post updates!

Thanks again for all your help and guidance (I have a computer science degree, and theatre lighting is new to me!).
 
Well, it looks like all of us are way off base on the control voltage except for @RonHebbard. Those dimmers want
0 to -10vdc. It is a negative voltage by the way Ron!
If you compare the OP's excellent photo of the demultiplexer board to the LCMD-48 Rev6 configuration sheet I posted earlier, one can plainly see that it is configured for 0-10vdc NEGATIVE output.

So, @crippit, the 18v you are measuring is surely a supply voltage or "take control" line to your remote stations and NOT the dimmer control line. This is why if you need any more help, we must have similarly detailed
photos of ALL of the houselight system control wiring!

View attachment 21542
The FOH lights seem to operate on a different control voltage to the house lights. Which we also think is bizarre!
 
The FOH lights seem to operate on a different control voltage to the house lights. Which we also think is bizarre!
Good evening;
You're in Montreal; you might consider Shaun Johnson's Canadian designed and manufactured dimmers, interface, and relay systems.
A community theatre in Burlington, Ontario removed 36 Strand 3.6 Kw JTM's (A rack of 24 + a rack of 12 next to it + 12 ancient Art Gladman [Toronto in the 1950's]) and replaced them with four of Mr. Johnson's JS Icon 2413's. https://www.johnsonsystems.com/icon_series_wall_mount_pp.htm ) for a total of 96 1.3Kw dimmers: 96 dimmers mounted on two horizontal runs of CanTruss (UniStrut if you think like an American) occupying slightly less than 8' of horizontal wall space.
I'm a Johnson System's 'Fan Boy' ['Fan Geezer' actually]. All 96 dimmers were functioning flawlessly prior to the onset of Corona Chaos.
Toodleoo!
Ron Hebbard
 
Thanks everyone for your replies. I think we're actually going to look at removing the whole system and replacing it. Does anyone have any recommendations as to what to replace it with?

I think for now the house lighting will remain controlled by the JTM's but we'll look at a way to demultiplex the control from the existing system and link that through to DMX. We found someone who had worked on our system, and it turns out they had trimmed the cards to the point that Strand refused to service the units any longer. We also have at least 1/3 of the dimmers which no longer function due to shorts (which killed the dimmer cards).

At this point we're going to bring in an expert, if you are interested I can continue to post updates!

Thanks again for all your help and guidance (I have a computer science degree, and theatre lighting is new to me!).
I am not sure why you simply wouldn't replace the houselight dimmers with what you would be using to replace the stage lighting dimmers. Johnson Systems has remote stations as well. I'm sure they can supply a fully integrated system.
 
If you want to go ETC, contact Charles Cadieux at CETEC Group. He can get a quote setup and sent to your favourite dealer (LSM, Solotech, XYZ, Christie Lites)

PM me for contact details.
 

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