I have been working on a Sony CD player and the service manual is a little less then clear on the adjustment procedures.
There are two adjustments. Focus Bias and Focus Gain. I used a Presonus Studio test CD on the 1Khz 0db track for adjustments. Manual states 200Mv divisions and 500ns on the scope.
I have a scope that is good to 60Mhz (Sencor SC-61) and states its usable to 100Mhz. But i could not get a real clear eye pattern on my screen to adjust the Focus Bias. the pattern looked very fuzzy and out of focus. Maybe it is time for a new scope?
Adjusting the Focus Bias i noticed the amplitude of the signal would rise and then fall slightly from one direction to the other. so I just tweaked it to get as much amplitude as I could and hope that is good enough???
The second adjustment, the focus gain adjustment. is not to clear on what or how to adjust it. it says:
Confirm the operation noise (white noise) from the two axis device(lens block of the optical pickup) is not abnormal. if the operation noise is too large rotate RV4 [the focus gain adjustment]. if the focus gain is too low, the focus cannot function and playback is not possible. if the focus gain is to high, noise is produced by scratches, dust and operation is not stable.
Ok, so I twiddle the adjuster and really didn't notice any difference on the scope. if I put my ear to the transport and listen very carefully I could hear the optical block make more noise if I rotated the adjuster one direction and if I went the other way, there was less noise and then it would skip or stop. so again I just tweaked it in the middle of the extremes and then tweaked it a little more.
What white noise are they talking about? where do i hear/see this white noise?
Seems to work well for now. it played even my most beat up, scratched disk. and even played a CD-R that was pretty scratched up. and only once did it skip.
But this leaves me curious as to what exactly the proper procedure really is to adjust these things?? Soon i will need to replace the laser in my Sony SCD-1 and i want to have a better understanding of how and what i am supposed to be adjusting? I dont want to be guessing "ok thats sort of good enough".
So Advice Please!
Zc
There are two adjustments. Focus Bias and Focus Gain. I used a Presonus Studio test CD on the 1Khz 0db track for adjustments. Manual states 200Mv divisions and 500ns on the scope.
I have a scope that is good to 60Mhz (Sencor SC-61) and states its usable to 100Mhz. But i could not get a real clear eye pattern on my screen to adjust the Focus Bias. the pattern looked very fuzzy and out of focus. Maybe it is time for a new scope?
Adjusting the Focus Bias i noticed the amplitude of the signal would rise and then fall slightly from one direction to the other. so I just tweaked it to get as much amplitude as I could and hope that is good enough???
The second adjustment, the focus gain adjustment. is not to clear on what or how to adjust it. it says:
Confirm the operation noise (white noise) from the two axis device(lens block of the optical pickup) is not abnormal. if the operation noise is too large rotate RV4 [the focus gain adjustment]. if the focus gain is too low, the focus cannot function and playback is not possible. if the focus gain is to high, noise is produced by scratches, dust and operation is not stable.
Ok, so I twiddle the adjuster and really didn't notice any difference on the scope. if I put my ear to the transport and listen very carefully I could hear the optical block make more noise if I rotated the adjuster one direction and if I went the other way, there was less noise and then it would skip or stop. so again I just tweaked it in the middle of the extremes and then tweaked it a little more.
What white noise are they talking about? where do i hear/see this white noise?
Seems to work well for now. it played even my most beat up, scratched disk. and even played a CD-R that was pretty scratched up. and only once did it skip.
But this leaves me curious as to what exactly the proper procedure really is to adjust these things?? Soon i will need to replace the laser in my Sony SCD-1 and i want to have a better understanding of how and what i am supposed to be adjusting? I dont want to be guessing "ok thats sort of good enough".
So Advice Please!
Zc
