Hi all, I new nothing about LD's until I purchased a faulty CLD-1750 on Ebay in March but liked the technology. I have a background in Analogue electronics and have successfully managed to breath life back in to several players including a player that was dropped by a courier!
I look forward to visiting these forums frequently. :-)
I came across this information today which explains how to correctly identify the illusive "NULL POINT" when calibrating a Laser optical block "grating" . I followed it today when calibrating my CLD-1750 and it works like a charm :thumbup:
The grating is a specialised lens in the optical block that splits the main laser in to 3 discrete beams. Two for driving the tracking circuits and one for data retrieval. If it's not set correctly then some discs will read and other older discs will not. Older discs tend to be more fussy about how they are read/played back. Maybe the tracks have shrunk over the years who knows! I would be very interested to compare my Pioneer calibration disk with my older "fussy discs". Either way if your laser does not tack properly then you are out of luck and your player will eventually reject the disc.
You do need an oscilloscope to check for the tracking signal.
I've included some pictures of an old optical block I have so the curious amongst you don't have to take your player to pieces! - Anyway this is like my 3rd post here so I do hope that you all enjoy.
NULL POINT.JPG
The laser grating slot for calibration. Laserdiode can be seen to the left (solderjoints). 20200710_101111_resized.jpg
Grating and prism for splitting the beam. 20200710_101040_resized.jpg
Grating and Laserdiode (rear, solder joints) 20200710_101027_resized.jpg
Laser Optics/beam splitter and lens that directs the information from the LD back to photosensitive components to generate the EFM signal for decoding.