CD80 Rack

General CD80 rack info   CD80 ramp and power supply cards 
CD80AE power supplies   CD80SV fuses   Non-Strand upgrades

Strand Lighting CD80 dimmers are the industry standard.  Tough, reliable, virtually indestructible — heck, you can even stand on the modules (except for the Supervisor or SV modules); they are the work horse of many Hollywood studios.

The Strand Lighting CD80 dimmer rack has gone through three generations. 

  1. First there was the ramp card AMX based unit released in the early 80’s. 
  2. Then came the Advance Electronics (CD80AE) version in the early 90’s that allowed for rack patching and DMX input.  In my opinion, this unit was a sort of kludge add on, but it worked surprisingly well. 
  3. Finally, we have the Supervisor rack (CD80SV).  This rack was thoroughly redesigned from the ground up.  Unfortunately, none of these dimmer modules are compatible with the earlier models.  The CD80SV rack is fully microprocessor based and is quite powerful and expandable.  I think this rack is quite ideally suited for architecture applications with its built in SWC, analog, and Outlook capabilities.  Unfortunately its weakness is the reliability of the main processor unit.

The CD80 dimmer modules can often be easily repaired as most of the parts are commonly available.  The most common failure is a bad SSR (SCR in some early 12kW modules).  Ignoring the SSR, the CD80 modules are usually free from major problems and often run over ten years without fail.

The two most common reasons CD80 electronics fails are because of lighting and ground loops.  Fortunately, Emlight offers complete repairs on the electronics including the  CD80SV processor.  It is entirely surface mount based and is not easily repaired.  And, from what I have seen, this processor seems to be very reliable - in failing every 5-7 years like clock work.

Even though the Strand Lighting CD80 dimmer rack is tough, a regular once a year maintenance program will prevent the more annoying and time-consuming failures like 12kW dimmers welding themselves to the rack because of a loose power or load pin.  Things to check are for loose connections and large amounts of dust and debris.  On the SV racks don’t forget to clean the air filter.


CD80 ramp and power supply cards

Tip 1: Question: Can I “hot plug” the cards?

Answer: No. Absolutely not. Do not, under any circumstances, plug in a ramp card or power supply card while power is being supplied to the card cage. You will either:

TIp 2: If your ramp cards have just been calibrated you should not have to adjust them again for quite a while. The only thing you may have to adjust are the power supply cards. The reason for this is that their output voltage is dependent on your input voltage, i.e. AC line voltage. The power supply card is calibrated by measuring between the green and black test terminals. You should measure 9.8Vdc with all the ramp cards at full. For ramp cards, I recommend you send them to a qualified service center to be tested, like Emlight (hint, hint), since more test equipment than is normally available to the average user is needed: an oscilloscope, a way to test the SSR outs preferably with a minimal LED load to simulate the SSR junction, a power cable to test the card cage on a test bench, an AMX signal source.

Tip 3: Question: What card controls what dimmer?

Answer: This is the ultimate head scratcher. You know you have a bad ramp card but which one is it so you can send it be repaired or swapped out. Here's a handy chart that may help you out (I made this ugly GIF graphic back when I was a partner with Lytemare):

Strand Lighting CD80 ramp card and PSU addressing

Basically, the rack is divided in columns and rows. Ramp means ramp card and PSU means power supply card or unit. The two number separated by the “/” are the dimmer output numbers that are in that slot for that column and row. 2.4kW dimmers are dual modules so there are actually two dimmer outputs in each slot. 6kW and 12kW dimmers you will only count the odd numbers of the number pair.


CD80AE power supplies

Tip 1: After spending years with Lytemare, my partner and I found that a certain resistor would always burn up over 3-7 years because of excessive current.  And once this resistor goes it’s bye, bye power supply.  It completely fries.  So we came up with a simple preventative measure.  Now, this is not a cure.  We both felt that either the power supply was mis-designed by the power supply manufacturer or that the power supply was being used in the wrong application as the CD80AE power supply.  We never figured that one out but on every every rack we saw the resistor was turning  dark brown in color.  Now this is hard to see as the PCB’s are very dark in color, black in most cases. 

Well, all we did is change R31 to a 1 or 2 watt resistor (metal film).  Now I am not going to give out the value of the resistor because I only want qualified techs attempting this mod and any tech should still remember the resistor color code.  Oh, and if you make a mistake ... that’s your problem and I assume no liability for this.  If in doubt, send the power supply in to get modded by a qualified tech.  Emlight does have these resistors in stock if you are game for this mod.  Since then Emlight has also sourced a replacement power supply but it requires minor metal and connector re-work to fit.


CD80SV fuses

Tip 1: Fuses and I mean big ones.  SV racks ship with a manual, keys, a security torx wrench and a bag with green stufff and other things.  The green stuff is your spare air filter.  The other things are what you are interested in.  Among them should be these rather large gold colored fuse jobbies.  There are three in a 3 phase rack mounted directly behind the fan assembly.  To get to them you have to remove the fan assembly tray.  Don’t yank it out because the fans are still attached to the rack via their power cables.  Slide it out carefully and you’ll see three big old fuses mounted on the rear sheetmetal of the rack.  If you lose a phase on your processor then this is where you should look when you can’t seem to find anything else wrong.. 

Incidently, this is where an emergency transfer cabinet lands its mains sense wires to determine if the rack has lost power.  It’s a small thing and most people will never run into this but, when you do, it can be a stumper, just like it was for me on my first SV system turn on.

TIP 2: Prepare yourself for your processor going down if it hasn’t in over 7 years.  It will. Emlight repairs roughly 1-7 a month.  If it fails: LCD display goes away or flashes, rack drops into panic and the processor seems dead - then unplug the processor as soon as possible.  THe longer you leave it running in a failed state the more likely the chance that you will begin to cook of traces on the daughter board and the main board.

Now, for those of you who know about the infamous battery on the memory card, if it’s a smooth body unit it’s probably already leaking and destroying your board.  I’ve had these battery types leak while sitting on my shelf!  The good ones have about 3 ridges.  They will still go bad as the board is charging them wrong and destroying them but you should get a good 5-7 years out of it.    Here is where it gets interesting.  People try to replace the battery and destroy traces and pads because of poor soldering and desoldering skills or equipment.  They also don’t understand about ESD safety and almost always knock off a few surface mount diode s that are the size of a small black ant.  We’ve taken to having to do full visual inspections when end user work is suspected.  If ever a product needed to be retrofitted it’s this one.


Non-Strand Upgrades

Johnson Systems Inc. manufacture several retrofits for the Strand Lighting CD80 dimmer rack line.  We at Emlight have installed dozens of these over the years and they have proved very reliable.

TIP 1: If you have a completely screwy patch order the infrared printer and have the C/D patch printed out.  You may want to photo copy it as the paper is the thermal kind and will fade I believe over times (years?). 

TIP 2: The installing tech should have done this but make sure the setup is back upped to the E2PROM.  It will make you feel much better.

TIP 3: if you retrofit should act screwy and it was installed around 2005, the factory has tracked a batch of defective memory chips to a small group of ECU’s.  Apparently they can scramble themselves when hit by a very bad power event.  Call your dealer if you experience this problem.  The fix is easy and takes less than 15 minutes per ECU.  I rate this as a “meh” as many other products out there wouldn’t even survive a large spike or surge that can scramble this very small batch of memory chips.


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