DSO5102p. Channel marker does not match the signal.

easa

When both probes are removed, on channel 1 the channel marker does not correspond to a signal with a sensitivity of 10 - 1 mV / div.  


After self-calibration or an hour-long warm-up, everything is fine, but it disappears if the oscilloscope is reset.

On channel 2, the marker and signal always are match up.



What could it be? Tell me please. I can solder, there is equipment.

easa

Thank you, but as I already wrote:

After self-calibration or an hour-long warm-up, everything is fine, but it disappears if the oscilloscope is reset.

calibration after warming up, helps before rebooting. Then again, half an hour or an hour you need to wait until the mark is aligned with the signal. It seems that the thermal compensation of channel 1 is not working well.

easa

I will not be able to contact the seller, as my friend bought the device for me, and he replaced the hard drive on the computer from which he made the purchase. And he does not remember from whom he bought it.
Could you tell me what parts need to be replaced to repair the device.

easa

OK. thank. I also suggested that the problems were caused by this chip, but I decided to listen to different opinions. I will order it and replace it, then I will write here the result.

easa

Replaced part D102 (AD8370AREZ) - did not help. Any more ideas?

easa

OK.
All this, of course, is good, but why in the second channel this problem does not exist to such an extent. If in the first channel when the "cold" oscilloscope is turned on, the difference in the 10mV /Div mode reaches 2 cells, then in the second channel only 1/5 part of the cell. Miracles do not happen ...

easa

Can this effect be caused by the leakage of the transistor Q101?
Since during cooling with the help of a liquid freezer spraying on D102 or Q101, the signal line shifts down from the channel marker, and accordingly, after warming up, rises.