DJ Machines in motion
TLDR: The dots have utility and are not just to look cool. DJ’s use it as a tool to see what the rotating speed is, relative to the normal speed. A quick look at the dots will tell you if your Turntable needs a service or is faulty. Its due to the “stroboscopic” effect
Utility, using the dots as a tool
Observing the motion of the dots, you can visually see the relative speed of the platter depending on what lines appear to be static. A row will appear frozen and stationary while the rest of the dots move.
The stroboscopic dots are designed to be used as an indicator to show the change of the speed of the record relative to the normal speed. In simple terms it’s a way to quickly see how much faster or slower the record is.
This can be a helpful tool when keeping the music consistent and not going too far away from the intended speed of the record, making it simple to see that the rotational speed of the platter is consistent.
Issues can occur If the speed of the dots seems drastically inconsistent, jumping back and forth, or drifting when the line should appear static. There could be an issue with your speed, that can be tweaked or your pitch/speed slider may be faulty.
If you notice that the lines of dots do not line up, you will need to service the turntable and have the pitch slider looked at.
The physics behind this magic has to do with a concept called the stroboscopic effect. The light beam acts as a strobe, oscillating at specific frequencies depending on if you have a 50Hz or 60Hz turntable.
Pro Tip: Most new turntables can run on 50 or 60Hz power (It will say on the back of the device)
Buying a turntable from a different country?
If you are buying a turntable from a different country make sure you get the correct power rating for your country.
The fluorescent light will operate at 50 or 60Hz depending on what your local power rating is. 120V 60Hz is for America, Japan etc and 230V 50Hz is for Europe, Australia etc. For more information on outlet power, you can find all the power rating here