2D72 incorrect reading

Marco67

Hi everyone,


recently I discovered that my 2d72 device provides incorrect readings (DMM mode) for alternating voltages. Instead of reading 220VAC on a household outlet, it reads a voltage of 380-400VAC (verified with another instrument). I also noticed that it gives inaccurate readings for resistances and electrolytic capacitors (which it doesn't read at all). The oscilloscope and function generator are working correctly. The current firmware version is 2021090901 FPGA: V07. Do you have any suggestions?


Marco

Marco67

I tried to reload the firmware downloaded directly from Hantek, but nothing changed (I also tried the previous firmware). Since customer support refuses to provide assistance as it wasn't purchased through official channels (bought on AliExpress in 2020), this weekend, as suggested in other threads, I'll try to disassemble it and check the components around the CS7721CN chip. Hopefully, it's not the chip the issue...

Marco67

Although it may not seem to be of interest, I'll provide an update on the repair. I hope it can be useful for others.
As observed with others, the section near the chip has two resistors completely burned, R14 and R15, while a third, R16, is blackened but the value seems to be correct at 46.4K. I'll now proceed to order the replacement parts, including R16. I'll keep you updated. Thank you all.

ying

Marco67 replied at 2024-4-8 18:04
Although it may not seem to be of interest, I'll provide an update on the repair. I hope it can be u ...

Thanks for your information.

R14:  10K,0.1% 0603           

R15:  1K,0.1% 0603           

R16:  46.4K ,1% 0603

Marco67

Over the weekend, I got those busted resistors replaced. Problem solved, and now the multimeter's back in action, doing its thing right. Ran some comparative tests with another tool, seems to be all good. Only thing bugging me is the capacitance reading for 100uF capacitors, which should fall within the instrument's reading range. Despite checking multiple components, I couldn't get a reading.

Thanks, everyone!
Marco

ying

Marco67 replied at 2024-4-15 17:44
Over the weekend, I got those busted resistors replaced. Problem solved, and now the multimeter's ba ...

Capacitance test can not function? or only 100uF capacitors test issue? Please send a short video to study.

Marco67

So, as you can tell from the video (sorry for the crappy quality), I reckon I'm only having trouble with the 100uF capacitors.
Not entirely sure if it's actually a flaw with the tool. I don't recall ever testing capacitors before it malfunctioned. Maybe it's normal to have an overload for 100uF capacitors...

Would really appreciate it if you could give me some feedback

https://www.dropbox.com/scl/fi/w ... eg04un9e50go0d&dl=0

ying

Marco67 replied at 2024-4-16 19:26
So, as you can tell from the video (sorry for the crappy quality), I reckon I'm only having trouble  ...

Thanks.
But we can not open the link.
If it is convenient, please try to send a short video directly,or send to email: support@hantek.com

Marco67

I hope this is fine

https://dfiles.eu/files/iz42ywse6

let me know