My first DSO138 miniature el-cheapo oscilloscope arrived today; all the components loose in a small bag. The unit's main board is just 118 mm x 75 mm, give or take. The screen is a very usable 54 mm x 42 mm, give or take. It came with one instruction page for building, and one page as a user guide.
These are viewable at
http://akizukidenshi.com/download/ds/jye/UserManual_138_new_s.pdfOK, so my first job was to measure all the resistors and make sure I had everything. All the components were there, and correct. I just followed the numbered steps on the build guide. I'm glad I had a microscope handy and did this at work with our fine-tipped soldering iron, because it's really quite fiddly populating the circuit board. The SMD components came pre-mounted, but I had to put everything else on. It was straightforward, though, but took quite some time - about 3 hours all-up.
I made just one mistake - I put male headers where I should have put female ones, and I panicked and de-soldered. In actual fact, I could have fixed this error by just putting the female where the male was to go, and it would have mated OK. But anyway, I found that de-soldering headers doesn't go very well and I had to find a replacement 2-pin header (x2) which was easy enough, and after a simple diagnostic voltage check I jumpered a few points on the board to make it "live" and switched on the juice (9V).
Display comes on! Welcome screen! And then there's a trace. Hold my finger to the supplied alligator-clip lead (red side) and there's the trace showing something. Triggering is working! (auto, normal, single), and the inbuilt square-wave test signal appears to be displayed correctly.
So, 100% working first time. Very happy with that. The unit is of course just a $15 bare-bones thing, but I thought the assembly instructions were well done and easy to follow. The build quality looks great to me, and the screen is pretty damn good for the price (it's colour).
Beware, there are apparently a LOT of counterfeits out there, and often supplied with incorrect resistors, capacitors and/or missing bits. So, look for a genuine supplier I guess.
Anyway, now it's time to dig out my old televisor from storage and find a CD player from somewhere, and start to put some signals in and see what happens!