Control Board Fails

ESDControl Boards rarely fail, they’re usually misdiagnosed or murdered.

When control boards do fail it’s normally an output contact failure caused by age or an electrical surge like lightning or a technician shuffling across carpet before touching it.

It’s a fact; static electricity will ruin a control board faster than a fart can ruin a first date.

The proper term to describe static electricity is ESD (electrostatic discharge)

How much static can a human create? Up to 40,000 volts, more than enough to fry an unsuspecting PCB. To put the power of ESD in perspective, the shock you feel on a doorknob is somewhere in the range of 3,000 to 10,000 volts. One of the most common enemies of PCBs everywhere is one most of us use every day, the Styrofoam coffee cup. That innocent piece of Styrofoam can produce and store up to 10,000volts! How many times have you worked on a piece of equipment while drinking from a foam coffee cup?  Another interesting tidbit, ESD doesn’t necessarily kill the PCB instantly; it can actually cause damage that will lower the device’s lifespan from the tens of thousands of hours to hundreds of hours.

How? By burning away a portion of the electrical traces on its components. See the magnified picture below.

Fried trace

How many times have you changed a 5 year old control board, only to have the new one fail in a month, and its replacement fail within a year?

Crappy replacement boards? I don’t think so.

Here are some tips to help prevent PCB murder;

  1. Put the damn Styrofoam cup down.
  2. Don’t take a new PCB out of its anti static bag until it’s ready to be installed.
  3. Ground yourself before touching anything electronic.

We will cover more in depth troubleshooting in future articles. Stay tuned, and leave the Styrofoam cup in the van…

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Patrick is Zen HVAC’s diagnostic and training guy.

Patrick started in the trade the day he left technical school and never looked back.

He’s served in various technical and training roles in the HVAC industry but specializes in system troubleshooting and diagnostics, retro commissioning, and technical training.

His moto: If I can understand it, anybody can.

Patrick uses the Zen common sense approach to teach

Patrick’s Likes- His Wife, kids and dog. Old pickup trucks. Hiking. The industrial Revolution.

Patrick’s Dislikes- Taking work too seriously. Anything unintuitive. Emoticons :(

Patrick’s Favorite famous person- Theodore Roosevelt “I am only an average man, But I work harder at it than the average man”

Famous Patrick Quote- “Well, that was stupid of me”

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