[FAQ] Plextor PX-755A\760A\SA Refurbished -Wymiana OPU

[Stingray]

Napisany przez NightRanger

where is

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.

[czary2mary]

Napisany przez Stingray

Guys, how can we find out the calibration data?


I usually tested the donor and then simply replaced the laser unit, and it worked. Sometimes, under the control of an ohmmeter, I adjusted the adjustment resistors and looked at the scan results.

SF-DSxxx lasers are a new type and do not require manual calibration. Calibration data is contained in a QR code affixed to the laser. Reading it is not a problem. However, changing this data in the Plextor ROM is a challenge because there is no software available to access and operate Sanyo chipsets.

[Stingray]

Napisany przez czary2mary

in a QR code .

I read on forums that lasers that work perfectly at 3550 do not want to work on px760 without adjusting the resistors. The reason is probably the internal calibrations you mention.
could you please explain how to interprate them and compare these settings.

[czary2mary]

Napisany przez Stingray

I read on forums that lasers that work perfectly at 3550 do not want to work on px760 without adjusting the resistors. The reason is probably the internal calibrations you mention.
could you please explain how to interprate them and compare these settings.

I haven't encountered this problem with the NEC ND-3550. As I mentioned, lasers must be in perfect condition to have a chance of working properly in the Plextor. Just because they work in the NEC or LiteOn doesn't mean they are. Since you can't calibrate the focus/zoom/beam settings and other basic settings in the Plextor ROM, the only way to check/verify the lasers is to test/verify them. From experience, I can say that NEC/LiteOn lasers can perform differently in different Plextor units, from very poorly in one unit to perfectly fine in another. Sometimes you need to check/verify multiple lasers in a single unit.

[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.

laser playstation2.zip

[Stingray]

Napisany przez misiozol

ps2 laser.

Thank you for this manual, I have similar for CD players and it for reading function.
Please advice about recording due to this laser has separate variable resistors for writing CD and DVD.

[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