by George Taniwaki

Last week I had two small electronic devices fail. I tried to fix them both and failed. Here’s a short description of my attempt to fix the first one, a USB KVM switch. Along the way I ponder the role of industrial design and intellectual property rights in China.

I have two computers, a desktop PC and an iMac. Rather than have separate keyboards and mice, I share them and toggle between the computers using a KVM switch (the abbreviation stands for keyboard, video, and mouse). My setup is shown in the photo below.


Figure 1. My home computer setup, the KVM switch is on the desk, above and to the right of the keyboard

Last week the KVM switch quit working (after only a year!). I opened it up but could not see any loose connections. My guess is that the clock chip failed. Clocks are cheap but so is a new KVM switch. So rather than spend time and money trying to debug and fix this device I bought a new one for $9.50 on Amazon.

When it arrived, I noticed it looked just like my old one right down to the fact that the button on the switch was slightly off-center (see photo below). The only apparent difference was the printing on the case and the UPC codes.


Figures 2a and 2b. The front of the old KVM switch on left, new one on right

A UPC code consists of two sets of 6-digit numbers. The first 6 digits is a unique identifier for a given manufacturer. Each manufacturer is then able to assign the next 5 digits to products as they wish and then calculates a checksum to assign as the last digit.

The two switch boxes shown above had different manufacturer IDs and different product IDs, indicating they were made by different manufacturers.

This intrigued me. Both KVM switches are made in China. This made me wonder about why the UPC codes don’t match. Some possibilities I came up with:

  1. One company reverse engineered (i.e., brazenly stole) the other’s design for the KVM switch (even given the poor reputation Chinese companies have for respecting intellectual property, this seems unlikely)
  2. One company made the original design and licensed it to the other (seems unlikely, once the first company did all the work to line up suppliers why would it want to help a competitor enter the market?)
  3. Both manufacturers licensed the design from a third company that only does design and lets others manage the supply chain and manufacturing details (given the low-cost of the item, this seems an unlikely product category for a successful design firm)
  4. Between the time I purchased the first KVM switch and the replacement, the company changed its name, was acquired, or changed its manufacturer ID and product ID for the switch for some other reason (this seems most likely)

I was a bit concerned about the reliability of my new switch. If it has the identical circuit design of my old switch, it might fail prematurely. So I opened up both KVM switches to see the circuit board.


Figure 3a and 3b. The circuit board of the old KVM switch on left, new one on right

Surprise! They are not identical. The new one has three chips compared to four for the old one. And some of the chips are smaller. These smaller chips in the new switch have more pins (indicating higher complexity).  Fewer chips should make it more reliable (hopefully). Both have a 12MHz clock chip (which is the full bandwidth speed for USB 1.0 specification). Both have an identification mark of MT-201UK-CH which indicates they were both designed by the same firm.

Someday, if this KVM switch fails, I might buy one that supports HDMI video connectors. Then I will have the left monitor dedicated to Windows, the right monitor dedicated to Mac and the center monitor toggle between them along with the keyboard and mouse.


Go back to the photo in Figure 1. Notice that the image on the monitors on the PC are much bluer than the image on the Mac. I’m a color printing expert and I’ve futzed with the white point and color balance on both machines and can’t get them to match. Why is it so hard to profile and calibrate monitors?


Part 2 of this story is posted Aug 2013.

All photos by George Taniwaki