uSDC20D Clicking Problem (Noise Problem)

Dedicated to support for the microcontroller based uSDC20D
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uSDC20D Clicking Problem (Noise Problem)

Postby zootjeff » Tue May 24, 2005 3:41 am

Some uSDC20D units have a noise problem. Under noisy environments, the uSDC20D will click off and then back on for brief periods of time, and or cause random shutdowns.

The following is an explanation of the problem:
When you connect a big inverter or DC-DC PSU to the uSDC20D, it was creating a noise problem that was very hard to detect. This is only a problem on a small batch of units. These units were built with smaller filter caps. It is related to the temperature sensor circuit. The unit gets so much noise that it thinks it is having an over-temperature problem.

I was able to re-create the problem. I have my 400-watt inverter plugged into my cig lighter outlet, a motherboard with a Pentium 3 and 2 hard drives begin powered by it. I get the clicking with the ACC connected, with the car on or off. The clicking and the noise goes away when I turn off the inverter. I have verified this on a Oscilloscope.

I was able to fix the noise problem by soldering a resistor to the unit that filters the noise out. I have also upgraded the code so future units don't have this problem.

So everyone has a few options:
This is only a problem if you have clicking. If you don't have clicking, your unit is probably fine.

1. Perform the Mod yourself to clean up the noise.
2. I will take back the unit, do the mod (and/or update the firmware) and send them back to you free of charge.

Please send repair requests to

I'm sorry to all of you who's time I've wasted by this.


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