Problems with vertical possition calibration (deflection)

[Jaanis]

Hello
I bought new oscilloscope DSO112A in Electronic DIY Club (Aliexpress) store one month ago. It have problem with vertical position calibration (it problem was from first time). When input terminal is set to DC or AC, without input signal oscilloscope shown input voltage ~0,4 V (it depend of sensitivity selections). I tried Default and VPos calibration, but no succes, the problem remain. I filmed the videos where possible to see this problems. Video link https://www.youtube.com/watch?v=x4dPWJz ... e=youtu.be
Is it possible to fix problem locally, or I should solve this problem with AliExprss seller?
PS. I sent for you e-mail to support@... e-mail on week ago, but I have not get answer>
Best regards, Jaanis

[jye1]

It looks some components are malfunction. It is difficult to fix locally since it needs to replace an surface mount opamp. Please contact JYE Tech at jyetech@163.com for replacement.

[rahe55]

I assembled the 112A (firmware .....-211) and have a similar problem :

The trace remains at the top of the screen, whatever setting or calibration I try.

Pushing Pos Cal. gives clicking of relais as well as Default.

Otherwise device seems to be working ok.
Can access menus , move cursors for trigger and shifting picture etc.

Observation : MC34063 is running pretty hot.

in the attached picture : the upper left corner is the MC34063 at 70°C approx., the four blue points are the electrolytic caps.

What should I do with my unit - no docs available ?

[jye1]

It is suggested to contact JYE Tech at jyetech@163.com for replacement.

[rahe55]

ok - I did so - received form which I filled in and returned.


Thanks

[rahe55]

Thank you !

received new PCB today already soldered together from China .

Mounted together with battery 3.7V / 1100mAh into housing and working in good order now.