Setting laser current / Laser need break in time

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Just installed laser on tube CD player. At first would not play all cds so I adjusted 2 Allen keys by the plate that holds down the rod guides. This can't be where you adjust current right? It was a quarter turn from max I backed off from pre set setting. So far it's playing cds again. But I have no idea what I just did, can someone tell me please. Do lasers break in, it has metal involved, I was just curious?
 
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Lasers do not break in and normally no adjustment of laser current is needed as it is preset during manufacture. Adjustment of current is always by means of a preset resistor.

We would need to see a picture of what you actually adjusted to comment further. If you have adjusted the angles of the lens assembly itself then I'm afraid you will never get it correct without specialised equipment.
 
This is a Exemplar tube modded Denon 2900 I've had for over 10 years. In the last year it started having trouble reading disc. Last few months would only read 1 out of every 10 disc. I put a eBay laser in and would not read any disc. I adjusted the Allen key backing off maybe 1/8 of a turn and it now plays everything I throw at it. Why would doing what I did be wrong if it now works without a hiccup. I'm lost on this one.
 
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I can't answer other than to say that we don't know what this 'Allen key' you keep referring to actually does. Also we don't know the pickup type.

As a generalisation, mechanical adjustments are all factory done. The exception is an adjustment known as a 'diffraction grating' which is applicable to a handful of pickups. These generally require specialised knowledge and the adjustment screw is often not obviously visible but buried within the pickup body.

It's great you have got it to work but without knowing a lot more can't say why randomly adjusting something causes it to apparently play.
 
''.......I adjusted 2 Allen keys by the plate that holds down the rod guides.......''

Sounds to me like you have adjusted the ''Sled Runners'' (your rod guides ?) which will effect the relationship the Laser has with the Disc.
It needs to run parrallell with the Disc as it travels up and down and also sit parrallell to the Disc in the plane 90 degrees from this travel. (Difficult to describe, sorry).

What you need to do is put an oscilloscope on the RF Eyey Pattern whilst adjusting these Allen screws. You are looking for the Maximum pk-pk value but more importantly, the clearest signal.

Look for a Service Manual and follow the procedure. Thoroughly.

P.
 
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