How does it work? The electronic control systems used by Jacuzzi Whirlpool were/are made by Balboa Instruments. Their is a great effort to minimize any voltage on the topside to protect the spa user. To do so, they use a "piezo" switch for each button. When you press down on the button, it sends a signal to the board to change the function.

How do I know it has failed? Typically, if one or two functions stop working but the other still do, your topside is at fault. Also, if you see damage or water has seeped into the internal parts, time for a new topside.

Can I switch from an analog (dial) topside to digital? No. Topsides have to match their pcboard. Installing can damage the board and the topside will not operate.

Can a bad topside affect the spa operation? Not typically. The only time the topside comes into play is when you press a command.

What if one or two legs are out on my digital. Does that harm anything? Not normally