EDI MK VII
dimmer modules, consist of very few parts, and almost all of them are easily replaceable. I even built one of my own modules, from sheet aluminum and surplus parts, that I had around. The difficult part to come by is the
connector in the center of the main
connector assembly. It deals with the control voltages, and was very popular 35 years ago. Even though the module design is not that old, they used a
connector that had been around for a long time. The only other parts are Solid State Relays, (
SSR)
choke coils and
breaker switches.
EDI even changed the models and manufactures of the breakers over the years. MY rack has at least three different model breakers, as our modules were purchased at different times.
While it is possible, it is very unlikely that either a
choke or
breaker would fail. The all to common problem is the
SSR. While the
breaker will protect the
SSR from overload, sometimes a dead short will take out the
SSR faster than the
breaker can react. Dead shorts are usually from cables that are not maintained properly. When a lamp blows out, the
filament will sometimes create a dead short for a moment, just enough to kill the
SSR, and too quick for the
breaker.
The solid state relays in the
EDI MK VII module are a 40 amp dual random or non-zero crossing. Most are manufactured by Crydom or a direct copy by other manufactures. The number is printed on the top of the
SSR. You can do a search on several electronics suppliers sites, using that exact number, and they will come up. They range from about $56 to $70 from component suppliers or
dimmer manufactures sell them for around $100. Replacing them is an all mechanical process, requiring a phillips screwdriver and a pliar.
The last time I looked, which was a while ago, Digikey had the lowest price. Although you might check Mouser.com as well.
The part # is 40DR2D and they are also used in older Teatronic and
LMI dimmers, plus I'm pretty sure several others.
Your school electrician should be able to change the part. Don't make the repair if you have not done it before or if you don't have adult supervision from a qualified electrician.