JYE Tech Forum

Dear JYE-Tech support team!

I bought a new DSO112A (FW 113-11201-211) from eBay, it works generally fine but when input terminals are shorted (input voltage is zero) or with coupling set to GND after clicking Vpos cal. button the yellow marker at the left side of the screen comes to zero voltage axis but signal line drops down and demonstrates SIGNIFICANT NEGATIVE ERROR. It depends on chosen vertical sensitivity and can be as high as -0.5V when vertical sensitivity is 0.5V/div.

Also, when signal parameters are shown on the screen, Vavg reading at 0 input voltage is measured as -0.5V under similar conditions.



It seems to me like a hardware-related issue. Can it be fixed fast locally (I'm an electronics engineer) or I should solve this problem with eBay seller?

Thanks.

Sincerely,
Sergey Pismensky,

Izhevsk, Russia.

Can you try Vpos cal. again without connecting to anything? In theory this is not relevant since the firmware will ground input internally at performing the calibration. But just try.

The other thing to try. Please first perform factory default restoration and then perform Vpos cal.

Hello.

Thanks for your reply.

I tried all of that -- no success, the problem remains. In case it cannot be fixed fast and locally I'll ask the seller to send me another one but before I do that please let me know if there is anything I can do myself. For some reason I cannot open schematic diagram downloaded as an archive from this thread: http://www.jyetech.com/forum/viewtopic.php?f=17&t=358 Can I get is from some other source and not archived?

The photograph I uploaded is to large to display in this forum, if you open it in a separate tab you'll see that nothing is connected to the input terminal. Coupling is set to GND.