DSO138 [1]: Assembly

I acquired a cheap oscilloscope, the DSO138, in kit. The first step is to assemble the pieces!

DSO138 [1]: Assembly

To test some circuits, and check power supply stability, I bought a cheap oscilloscope named DSO138 (rev 13804K).

DSO 138 Overview

This oscilloscope is a DIY Kit: you have to solder each component on the main board.
One comes with all SMD parts pre-soldered (PN: 13803K, replacing 13801K). The other is with only the main IC (the MCU) pre-soldered (PN: 13804K, replacing 13802K) - this is the one I bought.

For both configurations the MCU has been pre-programmed and no re-programming is required.

Major features of DSO138:

  • Analog bandwidth: 0 - 200KHz
  • Sampling rate: 1Msps max
  • Sensitivity: 10mV/Div - 5V/Div
  • Sensitivity error: < 5%
  • Vertical resolution: 12-bit
  • Timebase: 10us/Div - 500s/Div
  • Record length: 1024 points
  • Built-in 1KHz/3.3V test signal
  • Waveform frozen (HOLD) function available
  • Save/recall waveform

This first blog post will illustrate the soldering steps, in accordance with the user manual.

User manual

I scanned the documents for you:

Package content


Components bag


Circuit boards

Main board

DSO138: Main board side 1

DSO138: Main board side 2


DSO138: Screen board side 1

DSO138: Screen board side 2

Assembly (step by step)

SMT resistors on main board

DSO138: Solder SMT resistors on main board

SMT Chip: U2

DSO138: U2 chip soldering

U3 regulator and Resistors

DSO138: U3 regulator and resistors soldering

HF Shokes, diodes and oscillator

DSO138: large resistors, diodes and oscillator soldering

USB Port

DSO138: USB port soldering


DSO138: buttons soldering

Ceramic capacitors

DSO138: capacitors soldering

Transistors, Capacitor trimmers, LED, Power inductor, DC socket

DSO138: Transistors, Capacitor trimmers, LED, Power inductor, DC socket soldering

Electrolytic capacitors

DSO138: Electrolytic capacitors soldering

DC Jack, Slide switches, BNC connector, pin headers

To solder the BNC connector, heat it long enough
DSO138: DC Jack, Slide switches, BNC connector, pin headers soldering


Two jumpers have to be soldered :

  • JP3
  • JP4 (if the voltage is around +3.3V at TP22)

The other jumpers (JP1, JP2, JP5 and JP6) have to be open for normal running mode.

Main board and screen board

DSO138: Result main board
DSO138: Result with screen
DSO138: Result with screen

Final product

The DSO138 is working fine! I will upload a video in a future post.
DSO138: Final product

Next step

Now that the DSO138 is assembled, I should calibrate the two capacitor trimmers.
After that, I will assemble the plastic box.