[alpal]

I opened up the camera & made the adjustment.
The value of the Pot R27 is 100 ohms.

The info provided by QHY is misleading.
They say 2.2 Volts but their Oscilloscope documents show 2 + .2 of a division
( because they are on 2 Volts per centimeter ) which is actually 2.4 Volts.
When I checked my QHY9 it was 2.4 Volts but the waveform does not look
identical to their picture.
I used 1 volt per centimeter to get more accuracy.
I can't see any ringing on top of the waveform but maybe my CRO doesn't have the bandwidth..

I adjusted it to 2.2 Volts & will test it at the first opportunity
to see if the black horizontal lines on bright stars have gone.

I bought 2 different types of 100 ohm preset pot so that I could install
one of them at an external location but I will see if the above works first.
I added 2 giant photos on flickr of the 2 PCBs - top & bottom.

see pic: