No test signal when grounded

[sanyok84]

Hi community!

I have just assembled my first oscilloscope and faced with the following problem: during initial callibration with 1kHz internal generator and GND mode (+terminal connected to generator output) i see nop signal - only the line. Even with the maximum generator amplitude. But i see a good result from the generator in DC mode. Voltage levels i have measured from external source are ok. Where should i look? I suppose i have short circuit somewhere on analog PCB, but i have looked many times and found no mistakes. Initial voltage testing from control points are also fine. The firmware seems to be latest. Please help me with advice.

[Diabolo]

Hello,

GND puts the oscilloscope input to a mass, so the signal can not be seen.

Regards,
Diabolo

[Petroid]

Yes, that is what GND does. It is used for zero level calibration.

[sanyok84]

The manual states for adjusting C3 and C5 through the test terminal. In previous step i was asked to select GND. Thats why I thought i should do these adjustments in the same mode. Thank you, this means i did everything right switching to DC and adjusting C3 and C5 in this mode. Thank you again!