A while back I ordered a DSO138 Digital Oscilloscope from Banggood. It showed up a couple of weeks later and I put it together. When powering it I touched the red lead and no signal. So it was time to calibrate it. The kit comes with two pages of instructions, schematics and a troubleshooting guide. The calibrate instructions are as follows.
- 1. Connect the red clip to the test signal terminal and leave the black clip unconnected.
- 2. Set SEN1 switch to 0.1v and SEN2 switch to X5. Set CPL switch to AC or DC.
- 3. Adjust timebase to 0.2ms. You should see waveform similar to that shown in photos below.
If traces are not stable adjust trigger level so as you get a stable display.
- 4. Turn C4 with a small screw driver so that the waveform displays sharp right angle.
- 5. Set SEN1 switch to 1V and SEN2 switch to X1 while keep all other settings unchanged.
Adjust C6 so that sharp right angle waveform is displayed.
Simple enough however the 3.3V 1KHz terminal doesn’t work. When probed with the multimeter I’m getting about 1.44Vs. Keep in mind I tested all of the parts prior except the SMD parts that were already reflowed onto the PCB. I tried using a function gen with a 1KHz setting and still nothing. Doubled and triple checked the soldiering and everything is fine. Even used the multimeter to check continuity and all is fine. I even pulled out my old logic probes and the SMD parts are fine. So it must be software or somehow the PCB itself could be the issue. I jumped onto JYT Tech’s website since they are the manufacturer and see if they have a support number/email or what have you. Well they do but when I found the page for the DSO138 they have a disclaimer about fake counterfeits from ebay and even have a list of other retailers that sell them that are also counterfeit. Come to find out on their forms Banggood is a hit or miss for the counterfeits. One person on called RetiredProgrammer noticed his PCB was fake so I backtracked a bit and saw their mini guide “identify fake DSO138 kits using the indicators“. Well sure enough my PCB is fake. The real PCBs use a taper configuration while the fakes do not use the taper. By then I had spent a whole day trying to get it to work and find out I was only beating a dead horse I wanted to toss it across the room but didn’t. Here is a couple of pictures of my unit.
Same view from the identifying guide. As you can see there are no tapered traces. Notice the bodged Diode? Before I gave up to seek further help from the manufacture the damn thing literately came loose from a crappy soldering pad.
Sorry for the odd angle. Used my magnifying lamp to use as a zoom and add more light for the glamour shot.
Looking back I could of sworn the Banggood page stated it was in their US Warehouse yet the package was shipped from Malaysia. No wonder why it took a couple of weeks for it to arrive. The packaging was crummy. Typical overseas plastic bag with the parts wrapped in thick foam padding with a ziplock like bag with the parts inside. The thru-hole parts were stored in another plastic bag and the LCD was in bubble wrap. Mind you nothing was in a Anti-Static shielded bag. If you want to know more about Anti static bags I would suggest this video from the EEVBlog. Here is a picture of the packaging. I covered up the main part of the address for security.
I contacted the customer service from Banggood and got a odd request to make a video and upload it to youtube. I’m not a youtubber let alone have a video camera except for my crummy worn out tablet that I know I would get a reply stating “We can’t see hardly anything” of something on those lines. So here we are on the old blog page.
Now there are a few things about this. I’m not bashing Banggood at all. I know that sometimes counterfeits can end up floating into the mainstream market. For a example there was a boom of FTDI chips that are used for Arduino and their were counterfeits of the chip and FTDI noticed it and decided to commit terror per’sae by a driver update that would zap the counterfeit chips but left the consumer to suffer even though the consumer thought they bought the real deal and found out soon after the driver update the Arduino stops working. It happens a lot with all kinds of goods and even money. I myself ended up with a counterfeit 50 from the grocery store once. All I am asking is some sort of replacement that isn’t a counterfeit or at least store credit. Something that isn’t going to cost me more money or wasted time.