My DSO2D15 is a lemon and Hantek’s support sucks
In March I bought a DSO2D15 having read the posts on various forums which gave the consensus that the Hantek hardware was acceptable but the software was rather buggy...
On receiving the DSO and exploring is I would therefore suggest to those contemplating the purchase of a DSO2x1x to be aware that they could also receive a lemon and if so will get poor/no support from Hantek.
If anyone is interested in seeing the videos and screen captures of the problems, they are at https://drive.google.com/drive/folders/1MrwXf4mSIksYND4oyVKzrqQihpCTnqy2?usp=sharing
I'm interested (and I also bought the DSO2D15) and I have downloaded, watched all your movies, and looked at the screenshots. I have to remind myself that I made the "obvious" mistake of buying the DSO2D15 at a higher price than a DSO2C10. Both scopes are essentially the same with only a few components changed/added. So, I'm perhaps expecting more from my "expensive" product than is deserving of a low-priced unit. There are many similar scopes and the teardowns show that the packaging on the inside e.g. screening varies, so the Hantek is better than some of the dearer scopes.
Movie #1The offset you see is indeed not typical e.g. I don't get a similar result, so it does suggest you do have a "lemon", or at best, the results across different units are not well controlled (with a sample size of just 2).
I use my scope on the dc setting and occasionally on the ac setting. I don't use the gnd setting because I prefer just to turn off the channel. It probably has its uses e.g. for internal calibration etc.
The default button returns the scope to factory settings. It's not the ideal range to measure a small signal e.g. you wouldn't set a multimeter to 300V and measure the voltage across a 1.5V battery? On my scope, there is an offset, but it is much smaller. If you were measuring a circuit with small amplitudes, then you could "zoom in" and take a reading with the DVM that doesn't have this offset and the waveform doesn't show an offset.
There is a difference in how the gnd "works" across different V/div settings. I had both channels set to different V/div and noticed that switching to gnd was different from the two settings. At the default setting, you don't hear a relay and at 200mV/dv or lower you do hear a relay. I don't know how this is implemented, but I'm guessing the relay switches out the channel input and connects the input to gnd for the lower range.
On the higher ranges it doesn't, so it may try to pull the input to gnd e.g. a mosfet. The degree to which this "works" may vary, so different probes may have an influence. I don't know why it is done like this, except that relay contacts (when they move) cannot tolerate high voltages reliably?
I had a faulty probe and the supplier is sending me a replacement. I was provided with a PP150B probe and the replacement is a PP-250. The PP150B was "broken" because the probe tip was retained in the probe clip part - if that makes sense. So, I couldn't probe a circuit. With the 5v @ 1 kHz setting, I could get a decent square wave without any obvious ringing or overshoot. With the supplied probe, connected to a BNC - croc (and without a 50-ohm load), the output from the AWG looked terrible 5V @ 1 kHz square wave, which wasn't the same. I did see the overshoot and the lesson learned is not to use the BNC - croc clips as a probe, at least not without a termination. I could make my own 10x voltage divider as well.
The supplied probe combo with the croc clip/BNC, would exhibit the overshoot that you see e.g. the square wave going as much as 1/3 higher or lower. With the decent probe (and no croc clip/BNC) that problem goes away. I put this down to user error or inexperience. The faulty probe looks to me like a kit-probe e.g. one you would want not want to keep for everyday use. PP-250 is indeed a very nice probe.
Movie #2DSO scopes do not exhibit the clean waveform of analog scopes. The analog scope shows the average of many cycles and looks"nicer" but if you turn up the brightness you may also see additional content. The DSO has the advantage that you can trigger on one cycle and see a problem that would not show up on the analog scope.
The DSO2D15 does have some noise on the input. It does seem to be related to the probe used. Have you tried the same test, switching the probes, and comparing the sync issue? I was using my scope with the DVM to measure small offsets (I attached a scope print earlier) where the DC offset was 362 uV. The average is exactly on the zero volts line but there are a few 1-bit glitches up or down. I get the impression that the DVM is interpreting the scope's digitally sampled 8-bit signal and counting and averaging the values. With more glitches below than above, the average will be less than zero.
If this noise (sampling error) is on the signal and the scope interprets an increasing signal as a trigger, then it can trigger on a rising edge that can be on a rising or falling waveform. So what you observe is likely to happen. Moving the trigger point might help, but it wouldn't remove this issue entirely.
A better scope might either have a larger threshold, look for an increase across several samples and integrate the result to prevent false triggering. I don't have these issues and I'm using the better probe.
Movie #3I see a pattern here and the quality (or variety) of the videos is getting better. I can't see the probe for the Hantek but I do see the same probe used on the analog scope. Have you tried swapping the probes around?
Is it a phantom signal? Why would the scope only show the negative tails and not show them either in the signal or above it e.g. they could be there? Have you tried triggering below the square wave for a single shot? You might be surprised to consistently capture a "repeating" waveform outside of the region you are looking at.
The analog scope "sweeps under the carpet" lots of things that a DSO displays, especially at this price point. That's not a bad thing because we use a scope to identify problems and there is no need for it when things work.
Capture #1 and capture #2It is interesting that you have an issue at the base and not at the top. Are you using the supplied probe and does your circuit have a load so that the probe is measuring but not interfering with what you are seeing? If it's the internal AWG then you might infer that it drives the output high better than it pulls it low.
Did your scope come with a PP-150 (grey) probe with correction on the BNC, or a PP150B (black) with correction on the probe. Neither probe is ideal for the DSO2D15 because:
1. The PP-150 is a 100Mhz probe and (good as it is) isn't matched to a 150 MHz scope
2. The PP150B is marked as 150MHz (but other literature also says 100MHz)
The results of the PP-250 are so much better than the PP150B to suggest that the PP150B is just a starter/kit probe that's only fit for the bin. I noticed that the 10 version of the scope also only has one probe that is 80MHz.
PP-250 has a sprung loaded BNC, correction on the BNC, correction point isn't at one end of the capacitor and it is stable. The clip attaches with a positive connection (like a 3.5mm jack plug) rather than just pushing on. In my case, the probe tip stays with the probe on the better probe.
FWIW I don't agree with scopes (or probes) being marked in Mhz. It's misleading and they should be rated as "rise time aware". The supplier wanted to give me their PP-150 probe but the supplied manual shows that the PP150B is a 150MHz probe, so the supplier then offered the PP-250 as an alternative to the PP-150. Although you can disregard what is printed in the manual about the probe, having a better probe solves a lot of issues. My supporting argument was that with a PP-150 (that is 100 MHz), there is no value in charging more for the 150MHz scope over the 100MHz and they might want to refund the difference as the pp150B (in the box) was to a "higher" spec - of course, it's rubbish.
Any more videos?
Simon
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