Hi guys,
Looking for some assistance with some long term signal/ground issues my laser projectors are experiencing.
Happy to pay for your valuable time, as this has all been plaguing me for too long now.
Questions include:
- When I use multiple lasers (typically 4 or more on a single ILDA daisy chain with 100m ILDA run), then I get a static beam at about 5% - 20% power. This beam then disappears when I pull out the charger of my control laptop out of the AC power plug. The lasers and laptop charger are on the same power line, but this issue seems to be worse when they are running off separate AC breakers. It only seems to happen when I have multiple lasers daisy chained and never happens with just 1 or 2 units. I am going with Mr Brenner's single point grounding scheme, with ILDA pin 25 isolated from the other grounds. Does this mean I have definitely made an error in my grounding? Or do others experience this who know as a fact they have perfect grounding?
- What do I connect the foil shielding of my ILDA cables to? Laser projector/controller case (and therefore AC ground), or just leave the shielding floating?
- Do I connect my standard single-ended laser drivers to the R-, G-, B- pins, or ILDA pin 25? I use FB3's which by default tie R-, G-, B- and pin 25 together at the controller end anyway which just confuses me even more. Right now my laser drivers are connected to the corresponding negative colour value and NOT pin 25, and I worry that a loop could be present via the connection at the controller end, as they are separate within some of the projectors, but tied together in others. So should I tie all these pins together within all projectors, or does this make no difference and my problems lie elsewhere?
- For the central point grounding scheme as per Mr Brenner, do I actually need to have a CENTRAL POINT (like a literal single point smaller than 1/2 inch where all ground wires meet at exactly the same place) or can I just make sure that all DC grounds are connected to AC grounds by using jumpers from the DC side of each power supply to the AC side. This would mean that the "central point" would be stretched over the ~20" length of AC cable that connects each power supply, as opposed to a literal 1/2 inch central point. Would there be a noticeable difference here?
- Some of my laser drivers have ILDA pin 25 and DC ground tied together as part of their circuitry. What do I do in this case? Am I expected to make a buffer? Any alternatives?
- When I use a continuity tester between some laser drivers DC and signal ground, it shows resistance of a few hundred ohms, but seems to never settle on a particular value. I assume this is due to capacitors, so can I assume that these drivers are "safe" in terms of keeping the DC and signal connections separate for sake of good grounding? I don't have a capacitance meter but can invest in one if it's going to help diagnose problems.
Thanks in advance.