Agilent DSO1004A a repair attemp

[Lilf]

Hello everyone,
I have an Oscilloscope Agilent DSO1004A, channel 2 behavior is strange. The sinewave appear with a lot of noise
I connected Function Generator 1Khz sinewave directly to channel 2 with BNC to BNC cable. I change the BNC cable and still got the same result, I also connected a different F.G and had the same result all of the other channels are good. I teardown the DSO1004A to do an inspection of the BNC connector to the board, I check continuity it looks good. I'm thinking the connector itself maybe got damaged, Does anyone had something similar? Do you have any tips how should I proceed.
Thank you very much.

[Kleinstein]

The error does not look so much like an analog problem, but more like a digital problem, like 1 bit from ADC not reaching the destination. It may help to do a few more tests, maybe with a larger amplitude and maybe other ranges / DC shift.

[Lilf]

I appreciate your input, I will defiantly do that and keep posted with the result.

[Lilf]

I tried to change the amplitude higher and lower and the dc offset, also, I change between sine, square, pulse and get the same result. The noise appear suddenly out of no where. I attached video a short video that shows the signals with noise and after seconds the noise is gone it goes into a loop.