I’ve seen plenty of the DSO138 scopes in photos or videos that have been posted on here. I’ve also found references on here to the DSO150 (DSO Shell) and the newer DSO138mini. Just wondering which variant of all these DSOxxx scopes people recommend…?
I’m more after seeing what’s going on, rather than total accuracy…
Technically they are almost the same…
So you choose :
I have a DSO138mini. It’s cheap, and single channel so is good for seeing if a signal is present or not, but for actually analysing said signal you’ll need to spend a bit more. It would probably be good for a Kosmo module.
It came with a clear acrylic case that snaps over it and is powered via microUSB. I think you can buy a LiPo battery adapter board for it for offline usage.
Oh, also, if you do buy one intending to use it for debugging pick up some good probes - the stock ones are noisy garbage.
It’s good for beginners but you’ll hit the limits quickly.
If you just want to see what’s going on, it might be for you but I can’t recommend it for anything else.
From here:
DSO Shell has similar bandwitch as DSO138 but contains significant improvements in structure, mechanical, and operation.
Display and MCU are now mounted on the same board (mainboard) to avoid using inter-board pin-headers. Feedback from DSO138 usres have shown that soldering on the pin-headers are often problematic for many beginners. Analog channel is placed on a separated board which contains most user install parts. This brings in better separation between analog and digital circuits. Without the analog portion the mainboard is actually a general purpose control board that can be used in many other applications. The mainboard is fully installed (except a few through-hold components) and factory tested before packing.
DSO Shell comes with full enclosure. The front panel and top/bottom brackets are flexiable for easy user modification.
Rotary encoder has been added. It makes parameter adjustment much quicker and easier.
The sensitivity of DSO Shell has been extended in both directions and is higher and wider than DSO138. It reaches 5mV/div — 20V/div while DSO138 is only 10mV/div — 5V/div.
From here
[DSO138] is an old model. For new purchase, DSO138mini is recommended for its better structure and reliability.
I grabbed a DSO150 as a way to get back into DIY projects/soldering and was using it for a little while. It was quicky superseded by a 2nd hand hantek 4 channel digital scope. The DSO was fine for getting started, and it could probably be turned into a module fairly simply.
The build guide may shed some light on the subject.
Cheers,
(DSO138, but whatever)
or not so simply
https://modwiggler.com/forum/viewtopic.php?p=1998232#p1998232
(also DSO138)
Anyone know what this DSO138 power header is (and maybe even a source for the matching connector)?
I just assumed it was some sort of Molex connector. Someone asked a similar question on the JYE Tech forum a few years ago, but no answer…
Looking at this page, it looks similar (ish) to the JST-PH 2.0mm Battery Connector:
The JST PH 2.0mm battery connector is more commonly referred to in Micro RC as an MCP or MCPX connector
I think JST-XH is right. Certainly its pitch is 2.5 or 2.54 mm.
I should really have been posting my woes with trying to assemble my DSO Shell here. Essentially though, the soldering of the thru-hole components went well enough that any dramas were handled and everything mated into the shell. Step 4 of the instructions was checking the voltages, which also went well. Step 5 calibration was another matter though…
I dug it out of it’s box this morning and went back and checked all the voltages again, there are issues…
| Reference | Manual | Actual |
|---|---|---|
| Input | 9.3V | 9.184V |
| V+ | 8.35V | 8.371V |
| AV+ | 5V +/1 2% | 4.912V |
| V- | -7.86V | 0.238V |
| AV- | -5V +/-2% | 0.778V |
| V1 | 0V | 2.181V |
| V2 | 0V | 4.346V |
| V3 | 0V | 2.525V |
| V4 | ~1.65V | 8.333V |
As you can see V-, AV-, V1, V2, V3 and V4 are all incorrect. I found a post on the JYE Tech forum - FAQ, Tips, and Troubleshooting [Updated Oct. 11, 2017] that has a section titled 2: No negative power supply. V- and AV- have a positive value less than 1V.
The first thing they tell you to do, is to check the voltage at U5 pin8 to make sure power supply is connected to the chip. This voltage should be the same as V+. Not quite sure how to do that when it’s a SMD chip that’s sandwiched in between the two boards… 
Step two, is to visually check all pins of U5 to see whether all of them are soldered good. Check the soldering of C12 and C13 as well. The soldering of U5 looks good to me, and I’ve also checked the continuity and soldering of C12 and C13 and both seem good as well. So I decided to take a photo of the chip with a macro lens:
Not sure, but that doesn’t look too happy. Not sure if I’ve wellied it with the soldering iron, or it’s it’s burnt out internally. Might buy one and see if I can replace it, although I’m not sure how I’ll get the iron tip in between those electrolytic caps and header pins…
Yeah, that looks an awful lot like chips I’ve plugged in backwards.
Rather than just rushing out and buying another one of these, I thought I should really have a go at replacing that ICL7660 first. First try at anything SMD, gosh that’s fiddly. Had to remove all three capacitors, then lifted three pads while trying to remove the chip.
Here’s my Kosmo DSO138:
(My display is a little cockeyed on its PCB and there’s not enough play for the mounting screws to correct it — maybe I’ll drill out those mounting holes a little sometime.)
Slide switches, tactile buttons, and trigger indicator LED are mounted to an auxiliary PCB mounted behind the panel. Also on this board are a Eurorack style 10-pin power header with 10 µF caps and power reversal diodes, and a 9 volt regulator and TL072 op amp with associated passive components.
A BNC jack and a 1/4" phone input jack are mounted on the front panel. A toggle switch selects whether the scope input is connected to the BNC or to the 1/4" jack signal after being buffered with the TL072. The latter signal, buffered, also goes to a second 1/4" panel mounted jack, so the signal can be passed on to another module.
Also on the front panel is another toggle switch, controlling the 9 V power. (It’s good to power off the scope when not in use, for at least three reasons: the scope draws about 130 mA current on the +12 V rail, it probably puts out some digital noise you don’t want getting into your synth sound, and leaving it powered off when not in use will help extend the life of the display.)
The main DSO138 board is mounted perpendicular to the front panel. I used a 3D printed carrier and long spacers to attach it. The display board is parallel to the front panel and connected to the main PCB with a ribbon cable. More ribbon cables and a couple wires connect the auxiliary PCB to the appropriate points on the main PCB.
Design files, Gerbers, STL for the mounting fixture, and docs in the GitHub repo:
I’ll put my extra boards and panels up for sale on Tindie sometime soon.
That looks awesome. Been thinking about mounting a DSO to my case since finding out they existed…
Finally did a video!
