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Hantek 2C42 random pulses in roll mode

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Post time 2019-9-19 23:33:06 | Show all posts |Read mode
I recently got my Hantek 2C42 and found out that in Single trigger mode scope just randomly triggers on nothing, showing a flat 0 V line or a voltage spike.

Later i dicovered that it happens even if coupling is set to GND, so i tried to take a better look at what's happening using roll mode and saw distinct voltage spikes happening randomly.



And there is another problem in roll mode, when channel coupling is set to GND, channel trace lifts up independent of vertical scale. So, for example at 100 mV/Div trace lifts to 52 mV, at 1 V/Div  trace lifts to 520 mV and so on.

  

But when AC or DC coupling is selected, trace stays near 0 V.



I would like to know why this is happening and how to fix it.
I assume this is due to errors in firmware and hope it will be fixed soon.



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 Author| Post time 2019-9-20 07:46:52 | Show all posts
Edited by Equizer at 2019-9-20 07:49

Fixed random voltage spikes by downgrading FPGA software to V02, however traces are still lifting in roll mode.

I hope manufacturer will recognize this issue and fix it in next FPGA software update.
Also some feedback from manufacturer representative about this issue would be nice.

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Post time 2019-9-20 12:26:04 | Show all posts
Don't hold your breath waiting for a feedback, Hantek's staff is too busy rushing to release a new buggy half-finished product or simply don't care.

The voltage offset in the channels is an inherent problem of this device, I reported it some time ago, never got an answer: https://www.eediscuss.com/forum. ... 2&fromuid=26055
I called the attention for the problem again in another thread, while solving a problem in a different product: https://www.eediscuss.com/forum. ... 8&fromuid=26055

Others also noted that, again, no solution: https://www.eediscuss.com/forum. ... 4&fromuid=26055

This "lifting" you call in the traces (offset) is normal in the oscilloscopes but it should be compensated during the calibration. For me, the offset changes depending on the volts/div setting, number of channels on or if the charger is connected. Running the calibration while charging yields the best results for me, try it to see if it improves in your case (leave the device on for about 15min to warm up before the calibration).

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Post time 2019-9-20 15:46:53 | Show all posts
Equizer replied at 2019-9-20 07:46
Fixed random voltage spikes by downgrading FPGA software to V02, however traces are still lifting in ...

Please give me the software version of your scope to study.

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 Author| Post time 2019-9-20 19:08:20 | Show all posts
ARM software version is 2019082801
I tried to downgrade only ARM software, while still on FPGA V04 but it didn't help.

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 Author| Post time 2019-9-21 05:04:25 | Show all posts
Also noticed things like this just randomly showing up in roll mode on FPGA software V04 (no probes or anything connected):
  

Maybe FPGA chip is defective?


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 Author| Post time 2019-9-23 05:05:10 | Show all posts
Edited by Equizer at 2019-10-2 04:38

Video of typical issues with my device

https://filebin.net/ziz03voyvlhwtei6/MOV_0706.mp4?t=3wv5fioo




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Post time 2019-9-23 14:10:42 | Show all posts
I tested it and found something similar (I have FPGA 4 and ARM 219082801), not as bad but, eventualy there is a pulse in roll mode with the channels set to GND coupling:


Bug bonus: if you set a channel to GND coupling and put it in roll mode, when the trace is moved to bellow the first square after the centre line, the trace disappers and you will find it on the top of the screen, with AC and DC coupling it works fine:



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 Author| Post time 2019-9-24 03:38:07 | Show all posts
I think it gets worse when i increase time per division value, try to set 2s per division in roll mode and see what happens.

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Post time 2019-9-24 11:57:00 | Show all posts
I will test and feedback our engineer to modify.
We will update it in the next version. It may take several days.
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