Need diagram for Electro Controls 6424B dimmer module

Is this a "bolt-in" style or a "slide-in" model? I assume you mean 2.4kw (2400 watts) not 24kw (24,000 watts)!
I may have some documentation but can't access it until the end of next week.
Almost all Electro Controls dimmers have screwdriver pots for adjusting the low, mid, and high points of the output curve. The triac usually fails as shorted full on. The optocoupler IC is another frequent culprit.
Looks like the low end pot needs to be tweaked due to aging components. Knowing which pot is which (unless labelled on the pc board) is a different matter and sometimes adjusting one affects the others.
If you could post a photo of the unit and a closeup of the firing card and triac that would be helpful.
 
Hello microstar,

Thanks for the prompt reply. I did forget the . in the 2.4 KW rating of this pack.

It is a bolted in rack mounted dimmer. I have not removed it from the mounting.

There are no markings on the PC board to identify the purpose of the open faced pots.
The unit is part of a large rack located in the basement of the church.
It was installed after the restoration of the roof and ceiling following a fire that burned off the entire roof in 1970.

Please share whatever information you may have including the source for replacement parts.

Sincerely
KEN
 
Your unit is what I thought it was. Here it is on eBay:
I do have the complete factory calibration instructions, just can't access them until next Saturday.
You could buy one of the eBay units for parts, especially the triac.

Screen Shot 2020-02-08 at 7.48.25 AM.png
 
By far, your best resource is going to be Steve Short at Lite-Trol.
.
 
Your unit is what I thought it was. Here it is on eBay:
I do have the complete factory calibration instructions, just can't access them until next Saturday.
You could buy one of the eBay units for parts, especially the triac.

View attachment 19325
Thank you for the reassurance. That is the unit we have.

I sure could use the calibration information and a schematic if you could help with that.
Sincerely
KEN
 
Hello microstar,

Have you located the information you thought was in the office?

I have not looked any more at the church office since the units are so old the data may have been trashed.
Sorry some folks take these papers out of the equipment for "safe storage" elsewhere.

KEN
 
Theatremgr.... I forgot to add that you need to use an iron-vane voltmeter or more commonly available "true rms" digital meter to adjust to factory specs.
An ordinary digital meter will not give you true readings on a dimming system.
 
Hello microstar,

Thank you for this information. I also appreciate your comments on the proper meter to see the results of the calibration.

I wonder if the dimmed signal is LED friendly?

Sincerely,
KEN
 
With very rare exceptions, all stage lighting LED fixtures have their own dimmers inside and need constant power from a standard wall outlet or a non-dim or relay module in the dimmer rack because of the switching-type power supply in the fixture. Also you would not be able to change color with an external dimmer.
Do not try setting the dimmer at full and think that is the same thing because there is still a distorted waveform from the triac. A control console sends a DMX signal to the fixture to control the dimming, color, etc. over multiple channels. What control console do you have?
 
Hello microstar,

We have DMX controlled PAR Can fixtures in the sanctuary and the theatre. The house lights are incandescent and there are 6 60 Watt bulbs in each of the 12 fixtures. We would like to change out the incandescents for LED if the dimmers will operate them. These are the house lights in the church sanctuary.

The PAR cans are EPAR QW by Elation. We control them by a Livitone console in the church and by VISTA board with Windows 10 pro computer program.
The DMX are working fine. We are only 300 feet from the power company sub station and the building is fed with a three phase 220 Volt service.
 
Hello microstar,

Thank you for this information. I also appreciate your comments on the proper meter to see the results of the calibration.

I wonder if the dimmed signal is LED friendly?

Sincerely,
KEN
@theatremgr LED friendly??? If your LED's are smokers, they'll probably love it.
Toodleoo!
Ron Hebbad
 
The dimmer output would be the same as pretty much any standard dimmer. Unless the LED fixture is specifically designed to work with a standard dimmer, it oughtn't be used. Nearly all theatrical LED fixtures are not suited for use on dimmers. Some household LED bulbs are dimmable and probably would function after a fashion, though most do not dim down to zero or up from zero very nicely at all.
 
Echoing DrewE, the compatibility of dimmable LED bulbs with your dimmers can only be known by trial and error. You would need to replace all the bulbs in one fixture and see how well the dimming works. Chances are they will suddenly drop to zero as they almost fade out and may pop up from zero to a low level when fading up. This may or may not bother you, but very likely not as smooth as with you incandescents. Leaving one of the six bulbs incandescent may smooth the dimming.
Since there are probably multiple fixtures on a dimmer, this would skew the results of your experiment too. You would have to replace all six bulbs in every fixture on a dimmer to actually see what the result would be and if it is acceptable. Just be sure to choose the "correct" color temperature and lumen output to match what you've got.
Or maybe bump the color temp up a little for a "newer" look.
 
Older dimmers do not play well with LED lamps.
Now, on to the calibration....
Leak is probably the wrong word. What has happened is that your ramp generator on the firing card has drifted. This can be caused by dirty trim pots, but often it is something a little more specific. These look a lot like the HUB Electric dimmers I serviced two years ago. The failure point (if you can call it that) was a metal film capacitor in the ramp circuit. It doesn't so much "fail" as it simply drops in value. Often, there is enough room on the trimmers to compensate for the change, and it will be years before it drifts that much again. If there are only two trim pots on the board, you are in luck! One sets the bottom of the ramp (black level, idle level) and the other sets the top of the ramp (100%, full brightness) There is some interaction. On the bottom of the ramp, you are looking to adjust until your lamp extinguishes right as your fader hits 0. Too high and your lamp never goes out. Too low and you have a dead area at the bottom of your fader. On the high end trim, too high and your lamp hits 100% before your fader is all the way up. Too low and your lamp never makes it to 100%.
Often, I find the best test instrument to be a clear 100 watt light bulb! You actually want to set the low end so that the filament is a bit red, but no visible light. The top end, you want to be looking at the reflection of the light off the wall as you really can't look at the lamp. At that point, with the lamp still in circuit, confirm with a multimeter (preferably analog needle type) that you are hitting line voltage at 100% as you fader tops out. Now, dimmers by nature do eat a few volts, but you get the idea. The low end will probably be around 12 volts. Trust the filament more than the meter on this one!
If you find that your settings go crazy as you move the pot, then the pot is probably dirty. Usually moving them back and forth a few times, or a little contact cleaner will fix that. If not, then the pot needs to be replaced.
 
This dimmer has begun to leak current and the circuit has enough power to make the Quartz lights glow dimly. We need to identify the components to service it properly. The old RCA triac is no longer listed. This is a 24KW dimmer pack and is rack mounted. Any assistance is welcome. KEN
Hi! My name is Paulene Spika. Many years ago in a previous life, I was a factory authorized EC service person. I am very familiar with the the dimmers in your system. There were a number of versions of this circuit, they all used a unijunction transistor and a pulse transformer for isolation. Other than the low end leakage, does the dimmer work? If so, all it may need is a low end adjustment. The pc board has two pots, one is high and one is low. A true RMS meter is nice, but not essential to setting the low end for zero output. I don't remember which pot is which because it's been decades, but the low end pot will have an immediate effect on the output when you turn it. You can't hurt anything by turning the wrong one. If you don't have a meter, an incandescent lamp in a pigtail socket across the dimmer output is a good indicator. If I remember correctly, these firing cards were identified as a PC171. They didn't have the greatest curve, but they were fairly reliable. Those giant 1/2 inch stud RCA triacs can be replaced with a modern isolated stud triac that has a 40amp and400v or better piv rating. But you will have to get creative with mounting. Do not attempt this work if you are not comfortable or experienced with 120 volt electrical equipment. I put that in for the lawyers. I wish you good luck in your work.
 
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Hello Paulene Spika,
Many thanks for this information. This dimmer does work but does not go to "0" output even when the dimmer control board is turned off. I have been turning the circuit breaker off when the lights are not needed in the sanctuary. This is the first defect in the last 20 years. I will make some adjustment to the pot as you suggest. We found two lamps on this circuit were burned out and replacing them increased the load reducing the visible glowing.
 

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