Sega Dreamcast odd lens behaviour

[Fix_Metal]

Hello everybody.
A while ago I've started adding a VGA output to my DC.
It worked, but immediatly after I soldered it and tested the video output successfully, I realized it wouldn't read any disc anymore.
Unmounted the VGA stuff cause I thought of a short circuit or something odd. The lens never had any hint of read failure in the immediate past.
Nothing.
Later I bought a bunch of untested DC lens and tried to play with different combinations but nothing worked. I just thought they were probably broken since the beginning.

In the last month I bought a spare GD reader (the whole unit, including circuitry) from an HK supplier.
I then mounted it and NOTHING again.
The supplier tells me he tested this unit TWICE before shipping and he would send me another one anyway.

I tried to swap the circuitry between the original GD unit and the spare's, just because the spare is of a different HW revision (later) (my DC is daylaunch PAL).
Nothing, still won't work (with new lens and old circuitry).
It won't read originals from any territory, Audio CD, CD-R, nothing.

I'm willing to think of a different problem rather than the lens itself. I'm pretty sure the HK guy tells me the truth.
What the hell could it be? Ever heard of strange behaviour on GD side because of waddayaknow bad soldering?

[Fix_Metal]

Seems like you guys bring some luck. Or maybe it's just the forum.
After messing around a little more, I found that the lens cable was the problem.
I swapped it with the original from my DC and it lived again!!!
I really doubt out there there are still many complete optical DC drive replacements. I suggest y'all to get your own @ http://gamedoctorhk.com/ in case you need