DIY Oscilloscope Build Finale! | DSO138 Complete Build & Power Up

Foundation

Psalm 100:1-5 KJV

1 Make a joyful noise unto the Lord, all ye lands.
2 Serve the Lord with gladness: come before his presence with singing.
3 Know ye that the Lord he is God: it is he that hath made us, and not we ourselves; we are his people, and the sheep of his pasture.
4 Enter into his gates with thanksgiving, and into his courts with praise: be thankful unto him, and bless his name.
5 For the Lord is good; his mercy is everlasting; and his truth endureth to all generations.

DIY Oscilloscope Build Finale – Part 5

Welcome to Part 5 of the DSO138 oscilloscope kit build! This is the finale of the series, where we finish assembling the main board, attach the LCD display, power up the oscilloscope, test the signal, and install the board into the clear acrylic case.

This project started as a pile of components, and in this final part, it finally becomes a working oscilloscope.

What We Finished in This Video

In this part of the build, we completed several important steps:

Installed the LCD connector header
Soldered the J1, J2, and J3 connectors
Checked the power supply requirements
Verified the 3.3V test point
Soldered the JP4 jumper
Attached the LCD display board
Powered up the oscilloscope
Tested the input probe
Verified the square wave signal
Cleaned the PCB
Installed the board into the acrylic case

Watch the Video:

Installing the LCD Connectors

The first major step was installing the connector that allows the LCD display board to plug into the main board. This part needs a little extra care because the pins are held in place by plastic. If too much heat is applied, the pins can move out of alignment.

The best approach is to take your time, tack one pin first, check that the connector is straight, and then finish soldering the rest of the pins.

A good reminder from this step: don’t rush soldering. You want a solid connection, but you don’t want to leave the iron on the pin too long.

Checking the Power Supply

The DSO138 kit requires a 9V DC power supply with at least 200 mA of current capacity.

For this build, I used a 9V 500 mA supply, which gives plenty of margin above the minimum requirement. One thing to watch out for is that some kits may show a power supply in the product photo, but the supply may not actually be included.

Always double-check what comes with the kit before ordering.

First Voltage Test

Before plugging in the LCD board, we checked the voltage at TP22.

The expected voltage was around 3.3V, and the board measured about 3.32V, which was great news. After that checked out, the next step was to disconnect power and solder the JP4 jumper permanently.

This is an important step because it helps confirm that the power section is working before risking the LCD display.

Attaching the LCD Display

After the voltage check, the LCD display board was carefully lined up with the connectors on the main board.

This part was a little nerve-racking because the pins can bend if the board is not aligned correctly. The key is to go slow, look closely, and make sure all the pins are lined up before pressing the display board into place.

Once installed, the oscilloscope was ready for the first real power-up.

First Power-Up

This was the exciting part.

After plugging in the power supply, the display lit up. At first, the screen stayed bright for a moment, but after pressing the reset button and checking the controls, the oscilloscope display came up and started working.

That was the big success moment of the build.

Testing the Probe and Signal

The kit includes a small probe lead. After connecting it, I tested for a signal. At first, I did not see much from touching the probe by hand, but after adjusting the settings and connecting to the test signal point, the oscilloscope displayed a square wave.

That confirmed the oscilloscope was working.

Success!

Cleaning the Board

One step I almost forgot was cleaning the bottom of the PCB.

After soldering, there can be flux residue or small bits of debris left behind. I used electrical contact cleaner and a brush to clean the board. Safety glasses are a good idea because cleaner can splatter while brushing.

After cleaning, it is important to let the board dry completely before applying power again.

Installing the Acrylic Case

The final challenge was putting the oscilloscope into the clear acrylic case.

The case looked great, but it did not come with instructions, so this part involved some trial and error. The acrylic pieces also had protective film that needed to be peeled off. Once the film was removed, the pieces looked much clearer, but they also picked up fingerprints and dust very easily.

A few lessons from the case assembly:

Peel the protective film carefully
Clean each panel before installing it
Do not overtighten the small screws
Watch out for tiny nuts and screws
Make sure the acrylic layers are facing the correct direction
Be patient with the side panels and button caps

The case assembly took some figuring out, but once everything lined up, the finished oscilloscope looked really nice.

Final Thoughts

This was a fun project and a great soldering practice build. The DSO138 oscilloscope kit gives beginners a chance to work with through-hole components, connectors, testing, troubleshooting, and final assembly.

The best part is that at the end, you have a working tool you can use in future electronics projects.

Thanks for following along with this build series. More beginner-friendly electronics projects are coming soon!

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