Oscilloscope Duo test points?

[MNKyDeth]

Ok, so instead of using my new oscilloscope this past weekend I spent it watching and reading pretty much everything I could. I feel comfortable in how I am supposed to hook it up with the probes and how to adjust the controls on it.

I then spent a lot of time re-reading the laser swap and adjustment guide again as well. As in that thread there is a post referring to U101 and U102 locations on the Duo's pcb. However I cannot find U101 or U102 on any of my PC Engine Duo's I have sitting here. I even went so far to open up my US Duo to see if there were any differences in the labeling of the chips and locations and there really isn't.

However, IC101 and IC102 are right in the cd-rom location. Does the U in U101 refer to IC101 etc?

I still have very rudimentary electronic schematic reading skills, but am slowly learning. I found this post https://www.pcengine-fx.com/forums/index.php?topic=3586.msg120680#msg120680
It looks like I can reference most of what I need directly from the "A" on the variable resistor except on VR 105. But when I check VR 105 on my Oscilloscope I just want to make sure that pin 30 on IC102 is the correct location as I do not want to damage anything.

Also, when connecting the ground lead to something on these boards, since they are plugged into a wall outlet for me. I should make sure I put the ground lead directly on a ground location. Like the black wire that comes off the cd-rom platform and connects to the PCB near the VR's?

[Vimtoman]

If your setting up for CDR then I would just set the pots to a known working duo's.
They dont really vary that much.
If if does not works then change the Laser.
The laser only cost $25 and saves all the hassle.