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Last Updated: August 28, 2013

KOSO speedometer panel

Koso speedometer panel for motorcycle are so cool when fitted to the bike, in replacement for those analog type. With its digital display and colorful backlight. A head turner indeed. But when it broke down..i mean get defective, it is like a disposable item.

Shown is a Koso speedometer panel for yamaha mio. A friend send it to me by parcel in request for me to look at it if there is a way to fixed the panel.

Unfortunately, at the end of this page, you will see why i said its kind of a disposable panel, but if there is a way to find the right program, yes a program, a firmware for its MCU perhaps, there is a slight chance it can be revived and repaired.

  Moving on, so after it arrived, i open the panel to see how it looks like inside this sophisticated good looking digital panel. After removing all screws that holds the cover to the body. The PCB with the LCD is exposed as shown. The lcd is huge, it holds all the visual indicator like the RPM, the digital 3 digit speedometer, fuel gauge, oil temp, as well as  i think the gear indicator, and others.

Getting deeper, in order to see the top components of this panel, we have to remove the lcd solder to the board, this is tricky, and need good soldering technique to remove, the pcb is a double layer type, so lcd pins are soldered at both layer.
You need patience also to do this, do not try to pull out the pins, the lcd may get cracks and produce more problems.

aclose up view of the pins soldered to pcb. If you have access to a desoldering pump is an easier way to pull this one out.

With the lcd out of the way, the bare PCB is exposed. Time to look for the problem to where my friend told me it is a dead set, no power, no activity, no response to power supply. At first my diagnostic on the panel was that perhaps the voltage regulator section of the panel is the only problem, I was surprise to see something on top of one of the semiconductor IC that is soldered on the board. A HOLE...yes a hole on top of the IC, i thought it was just a dirt, and using alcohol cleaner to remove excess flux, the hole is there.

I searched for every data i can find of the IC all over the was then i finally gave up on this, for the said semiconductor is an 8-bit microcontroller, and when it says micro controller, it has a data or firmware written on it, that even if i tried replacing it with a new one, the firmware to be dump on the new IC is nowhere to be found.

So this speedometer is case closed.

I am still hoping there are like this speedometer panel that has a different problem in a unrepairable form with the MCU still in good shape. That is the only chance or if in luck a firmware is available.


Over voltage supply on the panel is the main culprit why the MCU get busted like this, normally they are installed wrongly on some small motorcycle with High intensity discharge fitted. Another is a wrong installation of the supply path that instead of isolating it on every accessories installed on the motorcycle, they just tap it anywhere within the supply path they can find, This kind of digital indicators for MC must be installed with its supply tapped after the ignition switch in a new path to avoid voltage surge made by other accessory.