Hung Chang 5502 Oscilloscope problem

[davefigueroa]

Hello!:
My name is Dave Figueroa, i am from Chile and I am 16 years old.
I have a HUNG CHANG 5502 Oscilloscope
My problem are the following: When I finish the calibration of the INVERT knob, I try to leave the trace at the middle of the CRT, at a first time the trace stays in the middle, but when I close the enclosure of the oscilloscope, the trace moves up or down. I do not know how the oscilloscope decalibrates itself!
I done the calibration again and I have the same problem.
The other problem is the movement of the trace when the oscilloscope turns on, because, when I finish using the oscilloscope, the trace is in the middle of the CRT and I shut down the oscilloscope, BUT when I TURN ON the oscilloscope at about 5 minutes or less, THE TRACE MOVES UP OR DOWN . And I think What's happening here?.
Awaiting your expert answerings
Dave Figueroa Osses


Other day I gonna post a photo of this oscilloscope

[davefigueroa]

First Photo: The Oscilloscope
Second Photo: The trace when I turned on
Third Photo: The trace at about 3 minutes

(the traces maybe is shorted because the camera is not faster than the trace)

[Armadillo]

Hi;

Please read and follow the instructions as attached.

Push in knob 22 [no magnification].

then update us again. Also tell us compare to file "hc.jpg", what were your button or knobs position.