AV Police Squad

Predicting Failure: The Five Keys To Maintenance

I am currently recovering from the flu thanks to my lovely kids. They got me good this time. Fever. Chills. Dry, hacking cough. Runny nose. I am just a big ol’ bowl of fun. Luckily, and torturously, I knew it was coming. The first sign was the kids getting sick. Then came a little tickle in my throat and the start of a cough. As soon as that weird, achy feeling settled into my entire body, I knew I had about 24 hours of brain activity left in me before succumbing to the dreaded “man-cold.” Some have said the man-cold is more debilitating than having all your limbs cut off, so knowing when one is coming can be very helpful. I can clear my schedule a bit, maybe drop the kids off at Grandma’s house for the day, and plan on just resting. It is much less stressful this way. When the man-cold finally took hold, I could just sit back and daydream about commissioning AV systems, after getting hopped up on the groovy cold & flu medications.

Part of commissioning systems includes creating maintenance plans to maximize their uptime after they are turned over to the client. By periodically performing a small portion of the AV9000 commissioning checklist on systems that have previously been put into production, you can actually predict failure, not just react to it.

Some examples:

  1. Temperature: Just like us, when devices start to get hotter than usual, bad things are coming. If a particular amplifier is running 10 degrees hotter than normal, it might be wise to swap it out before it fails during the CEO’s town hall. The trick is knowing how hot things typically run. Unless these numbers are documented, you lose the power of this easy predictive tool.
  2. Changes in Level: If a particular input on a mixer continues to need adjustment, something might be off. We had a mixer that required Microphone #3 to be raised 6dB to reach nominal levels. At the yearly review, we noticed that this was the second time this happened in six months. The preamp on the channel was failing, but it hadn’t yet died.
  3. Drop in Signal to Noise Ratio or Rise in Total Harmonic Distortion: When devices begin to fail, their electronic noise level may start to creep up. This manifests itself as the hiss heard at the loudspeakers getting worse and worse, or audible distortion creeping in on levels that are nowhere near the limits on the device. These criteria can be periodically measured and tracked with test equipment, but they can be heard subjectively as well. If a mixer starts to act funny without making any changes to the site file, it will probably fail soon.
  4. Decrease in Projector Brightness: Have you ever had a projector that didn’t seem as bright as it was supposed to, despite replacing the lamp? It is tough to notice without test equipment. First, who can subjectively remember how bright the image should be after not seeing it for a while? Second, even if you see the projector every day, the daily, infinitesimal decrease in brightness will also not be noticed. However, if you use a handy-dandy light meter to put a number on it, and track it every time the bulb is replaced, you can easily spot a failing projector before it ultimately fails.
  5. User Interview: This is probably the most important, yet most overlooked maintenance item in the history of maintenance items! First rule of doctoring: Whenever possible, ask the patient what’s wrong. First rule of AV maintenance: Whenever possible, ask the user what’s wrong, or what could be done better. It’s so easy, takes minutes to complete, gets everyone on the same page and makes the client feel like they are being listened to. However, most techs performing preventive maintenance visits just jump right in to function testing. They never take the time to learn about the whirring fan that kicks in after 2 hours of use, or the fact that the equipment closet gets scorched over the weekend when there is no AC. Either of these could predict impending system failure.

It is very easy to play the reactive AV maintenance game. It goes something like this:

Something stops working. Clients’ meetings go pear-shaped. Clients get irate and call you. You have to jump through hoops to work around their schedule to get access to the room, rush devices in for repair, etc. The client gets hit with an unexpected, un-budgeted emergency invoice. The system gets called nasty names. No one wins.

Now imagine it going something like this:

The amplifier has been getting progressively warmer over the past few months. You inform the client it’s probably a good idea to get a new one. They put it in the next quarter’s budget. They schedule you, weeks in advance, to swap it out at 11am on a Tuesday when the room is free. The users never know anything was wrong. They continue to whisper sweet nothings into the system microphones.

AV systems have a voice. They talk to us all the time. We just need the right tools to listen to them, and know when they are about to get sick. They might even be able to tell us when they just have a little tickle in their throat, or if they are about to get the flu. Applying these tests won’t necessarily get rid of all reactive maintenance calls. Users are still very “creative” in how they misuse AV systems. However, by applying periodic, quick, documented preventive maintenance testing on systems, these emergency reactive calls can be minimized.

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