by Milton Davis
- When absolutely everything in a system doesn't work except for one piece of equipment, it's probably that one working thing that's causing all the other problems.
- When de-soldering a chip from a circuit board, cut all the pins off of the chip first, then remove each pin from the board individually. This will result in far fewer broken traces and damaged holes.
- Lifting the shield of a DMX cable at the dimmer rack end of the cable can solve or isolate ground loop problems very quickly.
- Measure the AC RMS voltage between neutral and ground while your dimming system is operating. If it's 7 volts or above, it's a flickering problem waiting to happen.
- An earring is a great tool for resetting a Palm Pilot. It's also a good pickup line: "Pardon me, but could I borrow one of your earrings to reset my crashed PDA?"
- To a person with a hammer, everything looks like a nail.
- A piece of wide masking tape or duct tape is a good tool to use for cleaning up wire bits and metal shavings from the bottom of an electrical panel you can't otherwise clean out.
- A clipboard is another good tool for holding connectors down while you solder them together.
- Older dimmers can be trimmed by ear (no scope or meter!). Run the dimmer up to full output. Adjust the high end trim pot to the point where it just stops making buzzing noises. As long as you do them all the same, all the dimmers' curves will match.
- A 100W light bulb between phase and chassis ground is a great way to see if your grounding scheme is working. (This is a good tip, but is not necessarily safe if you don't know what you're doing. Also, if there's a GFCI in the system, this will trip it.)
- Information is no substitute for knowledge.
- The shield in control cable is not absolutely needed for DMX-512 to work. On long runs, the shield can actually cause a ground loop between a dimmer rack and its (separately powered) control source. Typically, you would leave the shield connected at the console end of the cable. This provides for noise shielding without connecting the ground loop at the dimmer end of the cable.
- A dimmer set to 50% should have an output measurement of about 78 - 85 volts if your meter is a true RMS type. A non-RMS meter will typically show about 60 volts. Non-RMS meters should not be used for dimming system troubleshooting.
- Setting a dimmer to zero does not prevent you from getting shocked. A dimmer with no load will have a measurable voltage that can kill. Always turn off the breaker before working with any wiring.
- Any tool can be a hammer. (OK, I just had to throw this in)