Pad controllers are MIDI devices that allow musicians and DJs to allow portable and custom music production. This model is USB-connected and weighs less than a pound.
After removing the pad controller from its packaging material, it felt like a nice piece of hardware in the hand. What I mean by this is that the plastic housing felt solid, yet had a nice texture to it. And, given its relatively small size (12" x 3.25" x 0.75"), the device was a bit heavier than I had anticipated. This LPD8 Laptop Pad Controller, from Akai, uses only eight knobs and 12 pushbuttons.
Akai's laptop pad controller
Well That Was Easy...
Wow. Of all the teardowns that I've completed, this one was the easiest to disassemble. The back plastic cover piece came right off without any effort after removing only eight Phillips screws.
The back piece removed
As can be seen in the figure above, the PCB's bottom-side is visible and has no components. This was a bit surprising as I expected many components to be used on this PCB (both bottom and top sides). Moving on...
After removing eight more screws and pulling off the knobs from the eight rotary switches (on the front side), the front-side housing piece detached effortlessly. All that remained was the PCB itself and the 12 pushbutton pads, and these pads, in two separate units, easily lifted off the PCB.
The front-side PCB, knobs, and pushbuttons
I mentioned before that I was surprised by how heavy this device felt. However, what's more surprising, as I discovered at this point in the teardown, was how heavy the rubber-like pushbutton pads were. They alone account for approximately 1/3rd of the total weight of the device—the total weight being 0.66 lbs (300 grams) while the rubber-like pads weigh in at 0.20 lbs (90 grams).
It SCREAMS High Quality...
Besides the rubber-like pushbutton pads being so heavy, I started to realize many of the other high-quality attributes contained within this assembly—and this is the "refreshing surprise" that I mentioned at the beginning of the article...this is a very-high-quality design.
- The rubber-like pushbutton pads are physically heavy, and robust, to withstand years of use and abuse.
- Each of the eight rotary switches are enclosed in a metal case of which are soldered solidly to the PCB (see the figure below).
The rotary switches are solidly soldered to the PCB
- The large rubber-like pushbutton pads have associated PCB landing pads which include a multitude of PCB traces that allow for quick, consistent, and constant continuity when the pushbuttons are depressed. Also, carbon ink has been applied to these PCB traces for providing excellent conductive and corrosion resistant traces (see figure below).
The carbon ink on PCB traces for large pushbutton pads
- The small pushbutton PCB copper trace landing pads have gold plating applied to them (either by electroplating or chemical plating) for purposes of (1) helping to prevent corrosion over time, (2) providing a good clean low resistance contact, and (3) providing an environmentally stable coating (see the figure below).
The gold-plating on PCB traces for small pushbutton pads
It's Obvious the Electrical and Mechanical Engineers Worked Collaboratively
I consider this demonstrated joint effort between the electrical and mechanical designers as a high-quality characteristic. More importantly, however, I consider this as a "yes, we do care about and take pride in our work and our products" trait.
The top-side of the PCB is littered with white lines and white boxes that represent component keepout areas. And although some of these keepout areas (such as those surrounding individual components) were established by the CAD librarian, the major keepout areas—like the two vertical lines and the boxes around the small pushbutton landing pads—were obviously created as a result of conversations and/or a 3D PCB analysis study between the mechanical and electrical engineers/designers (see figure below).
Component keepout areas
Only One Major Component
When reviewing the electrical components used on this design, there's only one major/complex component, and that's the processor. All other components are either passive elements, simple transistors, LEDs, or a voltage regulator.
- Processor: ARM STM32F102
- Transistors: NPN general purpose (1AM)
- Ferrite beads: no markings
- Crystal: 8.000MHz, no markings
- Voltage regulator: LD1117AG
Not only is this a high-quality product, but the designers implemented justifiable cost-savings measures.
A few examples include the fact that all the rotary switches are the same type/model, all the transistors are the same, and all sixteen removed screws are the same. The use of identical components reduces costs by lowering inventory controls, minimizing any training for assembly-line technicians, and reduces the number of tools needed to complete the assembly.
One final note on cost savings is the reduction of material costs related to the PCB design, itself, specifically the board thickness. This PCB is a quite thin design (measures only 40 mils) which allows it to be rather flexible in nature...although I'm sure the designers didn't have this type—my type—of flexibility testing in mind!
A thin PCB reduces costs and improves flexibility!
Akai's LPD8 Laptop Pad Controller is one high-quality-made product! Yet, it's a simple design that minimizes costs by reducing the number of components used and by using a thin PCB. Finally, I was happy to see the component keepout areas established by the mutual working environment between the electrical and mechanical designers. Nice work overall!