Sunday, 27 November 2016

DSO 138 Digital oscilloscope - getting started

A digital oscilloscope (DSO) is one of those handy tools, which looks quite intimidating at first, but as a matter of fact is not a lot more than a voltmeter, which will graph the voltage over time. It helps in visualizing wave forms and thereby can be of invaluable benefit, when troubleshooting electronical components.

Now a standard DSO will set you back somewhere around 300 Euros for a rather basic one. The DSO 138 from JYETech (or one of the hundreds of copies) will only cost you 17 Euros and that's with shipping included. As such some trade-offs have to be expected.

Let's get straight into the meat of it: a 200kHz sampling rate is nothing to write home about and a sensitivity range from 10mv/div to 5V/div isn't either. This doesn't mean in ANY case, that it's just a toy, far from it. Due to the small size, you're much more likely to "have a quite look" at the signal than with a regular scope, especially when you're like me, intend to mostly use it around bikes.

The first hurdle to climb: make it start. It uses a 5.5/2.1mm powerjack and you should use a plenty powerful power-supply (min. 500mA) to make it run stable. Otherwise you'll run into the same issues as I did below.

Bootscreen - mine came with 113-13001-42 firmware installed
 Once you have it running, the first thing you'll have to do is unplug it and install a little bit of wire onto the two open posts on the board in order to be able to use the built-in 3.3V/1kHz signal generator, which you'll need for calibration.

Hook up the probe and then zoom in until you can see the flanks of the curve and then adjust with the c4 and c6 potentiometers.

C4 should be tuned to get a sharp corner.

In case the DSO-138 doesn't boot at all, check the voltage in the lower left (ground) and upper right corner. (+9V)

A diagnostic menu can be reached by pressing the [OK]-button for 3 seconds. Depending on firmware version this can flicker around quite a bit.

You'll see this one being put to good use a lot in the future as I have to troubleshoot quite a few electronical issues on the Turbo TR1 ...

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