Anti-Static Point Removal in New CD Laser - diyAudio
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Old 12th January 2011, 08:43 PM   #1
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Default Anti-Static Point Removal in New CD Laser

Does anyone know where one can find a guide that shows how to remove the anti-static point in a CD laser assembly?

For example, my laser is a KSS-210a.

Also, can anyone answer whether a new laser has to be calibrated once installed back into the laser assembly?

Your answers would be appreciated. Thanks
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Old 13th January 2011, 01:40 AM   #2
singa is offline singa  Singapore
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Hi, Not all lasers have shorted links but is is seen on sony type lasers.
You don't need a tutorial because it is common sense.Just look at the
mini pcb where the flexible cable attaches,use a magnify glass if you are
an old person and there is 2 points or tabs that are shorted by solder.
Simply use a desoldering pump or solder wick to clear the short and you
are ready to install it in the base mechanism.The tiny pcb in most cases is
single sided so no reinforcement by through hole plating so it is easy to overheat and the
pad may come off so be careful .When the solder melts it's time to do the removal or sucking.

It is advisable to take a photo of the assemby before you take it
apart so you can put it together again.Just lift gently the white plastic
stoppers that hold the stainless steel guide shaft and push the shaft to remove the old laser head.Of course you have to pull out the flex cable first.

If you search there is a tutorial somewhere here.

As far as calibration is concerned the lasers have been set at the factory
so it is not advised to fiddle with the adjustments on the laser as it is
like plug and play.You may come across suggestions of calibrations but in
all likelyhood it is an old first generation cd player.Newer cd players because
to save cost and ease of production in most cases you do not see much
adjustment potentiometers or at all on a mordern pcb as the technology is mature in the interface ic for laser circuits.

As long as after the installation is completed and the cd player
reads and successfully plays a cd,you are good to go.

PS discharge whatever esd you have on your person,just touch any bare
metal surface before handling the laser or use a esd strap but most
people handle it without this action and manage not to zap the sensitive
electronics. A reminder that's all before you scratch your head. Singa

Last edited by singa; 13th January 2011 at 01:47 AM.
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Old 13th January 2011, 06:52 AM   #3
Mooly is online now Mooly  United Kingdom
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As far as the shorting link goes I would just add that it should only be removed when the pickup is in circuit. The briefest touch with an iron will pull the solder off on its own.
Some soldering irons can have high leakage currents so I always unplug the iron first.

Adjustments.
1. Pot on the pickup. Never touch this (laser power)

All other adjustments really require a scope however,

2. Tracking gain and Focus gain... do not touch.

3. Focus bias... can be adjusted by ear by listening to the "white noise" produced by the actuator coils in the pickup while playing a good disc. A null point will be found where the white noise is at a minimum and that is the correct position. Even with a scope and you won't get it any more accurate.

4. E-F balance... is a super critical adjustment so don't touch unless you have scope and understand how to adjust it.
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Old 13th January 2011, 09:25 AM   #4
oshifis is offline oshifis  Hungary
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Well, I fiddled with a Sony D-150 discman (following the service manual instructions), and the Focus Bias could be adjusted to the cleanest and maximum amplitude eye pattern. The Tracking Gain and Focus Gain could be adjusted by finding the position between the actuator noise disappearing and the low frequency modulation on top of the eye pattern disappearing. There is another adjustment called Tracking Balance which is unclear for me (the method described in the SM does not work). Is Tracking Balance, T-E balance and E-F Balance the same thing? Anyway, I adjusted it also for the cleanest eye pattern.
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Old 13th January 2011, 10:32 AM   #5
Mooly is online now Mooly  United Kingdom
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Quote:
Originally Posted by oshifis View Post
Well, I fiddled with a Sony D-150 discman (following the service manual instructions), and the Focus Bias could be adjusted to the cleanest and maximum amplitude eye pattern. The Tracking Gain and Focus Gain could be adjusted by finding the position between the actuator noise disappearing and the low frequency modulation on top of the eye pattern disappearing. There is another adjustment called Tracking Balance which is unclear for me (the method described in the SM does not work). Is Tracking Balance, T-E balance and E-F Balance the same thing? Anyway, I adjusted it also for the cleanest eye pattern.
E-F balance is adjusted while looking at the tracking error waveform and performing track searches. Use a slow timebase speed and adjust for symetrical "above and below" the waveform centre line. Hard to explain, easy to see on the scope as you adjust and keep performing track jumps.
Some manuals do refer to tracking balance.

Tracking gain is adjusted by looking again at the tracking error waveform, again at a low timebase speed and turning the gain up until a low frequency fundamental begins to appear. Back off slightly from this point and that will give a near perfect setting.

Focus gain is tricky... turn it up too much and pickup is noisy, not high enough and it's prone to shock and jumps easily. It's a very "non critical" adjustment normally.
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