[NightRanger]

Napisany przez Stingray

The laser unit from Plextor Px755/760, as well as from NEC 3550, has 4 variable resistors.
If I am not satisfied with the read/write quality, I measure the values of all 4 resistors with a precision ohmmeter and record them.
Two of them are visible (on top, as it were) and are responsible for reading CDs and DVDs. Rotation controlled by an ohmmeter (5-10% in ohms) counterclockwise increases the laser power.
The other two resistors are located deep in the back, where measurements are more difficult, and are responsible for recording.
I think this procedure reduces the service life of the laser significantly, so I rarely use it.
please see a practical example (laser from 3550 -> installed to Px 760):

It was a case of a very poor DVD laser, so I replaced it with another laser.

Usually, RW recording is the first to fail, and in this case, a small adjustment to R is usually sufficient, although in general it seems that these lasers are more suited to R recording, and RW quickly wearing them out.

thanks a lot, probably i'll give it a try with the actual 760a laser that don't work properly

Napisany przez misiozol

So in short, there are actually 2 types of calibration, power and quality/distortion/coil/etc. of received data.

In long, resistors are responsible for power output of laser hence if laser is dying adjusting them will give results to some degree and in general is not advised to mes around unless you have oscilloscope and can actually interpret data coming out during this phase of calibration. Now secondly about quality, you see all lasers are not equal and there are some distortion in reading data, this data is stored in QR code and during manufacturing process while bench test each laser like focus/distortion/coil power etc this data is later read decrypted and added to chipset as binary data and encrypted again. There is much much more to this tale, however if you interested in this you can read about xbox360 drive it's a must for basic understanding and ps2 drive how to pair and calibrate laser unit with console. This has been widely explained in user friendly manner and is relevant to all laser drives. Attached file will give you some degree of complexities with resistors how it suppose to be done in any drive on example of ps2 laser.

Załącznik 217271

thanks for all these infos