
Originally Posted by
GadgetUK
Surprised to see 3 pots on the pickup assembly =O
For a new laser I would set all 3 pots the same positions as the old laser was set to (measure their resistance with multimeter and adjust to get resistance as near as possible)
EF = Error Focus Balance - best way to adjust that would be to monitor TE / TER signal on a scope and pause CD track. Then you need to adjust the pot until the pulse has equal positive and negative peaks of that pulse.
Laser power pot is pretty much all you would need to tweak on a dying laser. Best way to adjust that is by monitoring the RF level on scope and start around 500mV and increase until it reads a pressed CD and perhaps a CD-R (if you plan on using CD-R). I am not sure what the correct RF level would be for the Neo CD, guessing between 500mV and 1.2v, but starting lower and working upwards will maximize the laser life. If anyone has a service manual for one of these let me know please =D
The Focus bias again related to focus and would only need adjusting if it was having trouble focusing - again you might be able to tell that from the RF level on a scope, but there are probably other test points better suited to adjusting the focus bias pot.
The best way to adjust any of these pots is whilst playing an audio CD. And there's another point - if the system crashes or resets etc whilst playing an audio CD - its not the laser or drive PCB as that wouldn't cause a reset. You would either find the audio stops or stutters etc. But in summary - set them the same as the original laser, and only tweak the laser power pot if need be.
The other possibility is the tracking needs adjustment - there should be more pots on the drive PCB?