Chap Seven: Topside Control 
 
 
There are several types of topside controls used on the Jacuzzi electronic spa.   
One style uses a combination of jet button and temperature dial.  More common 
are topsides with digital readouts and various buttons. 
 
HOW THEY WORK: 
 
Topsides with a dial temp control simply work by resistance. Turning the dial up 
or down changes the resistance that the board reads and either turns the heater 
on or off. 
 
The buttons on electronic topsides operate with piezo switches. They are simply a 
crystal that when press creates a small voltage that travels down the wire to the 
board. The board sees this impulse from the topside and responds. On some 
models it’s a step process; each time you press on the switch the board responds 
going to the next step. On other models its simply an on/off response. (Example: 
Press the air blower button on the topside and it turns the air blower on. Press 
again and it goes off) 
 
Topsides with a digital readout will have either a Liquid Quartz or Light Emitting 
readout. They operate the same. The Liquid Quartz displays a quartz style 
readout. The light emitting has light legs. Typically the higher end systems use 
the Liquid Quartz. 
 
The Platinum Series topsides are a liquid quartz readout with a light backlight. It’s 
the only topside Jacuzzi used with a liquid quartz. The remainder use a light 
emitting diode or LED. Some have more function buttons than others. Jacuzzi 
also used a topside with a Dial temperature control and a single jet button on 
many of their Z series spas.