Let's adjust laser beam focus and lens position

This is related to:
Optical readers and writers (DVD and CD) that have problems with reading one or more of the supported media (DVD or CD).

My interest is in Pioneer DVR-109,110 and 111.

Problems: Not reading or writing cds, but reading and writing dvds.

Try first: Clean the lens - if it helps, you’re done!

Possible solution: adjusting the laser beam intensity (increasing) and/or adjusting the tangential position of lens and/or complete optical mechanism.

All the information is highly unoficial and gathered from my friends and the internet (allmighty) :slight_smile:

This troubleshoot is not complete and is given in as-is form, I hope that together we can answer all remaining questions, and live and burn happily ever after :slight_smile:

Opened 110 looks like this:

And like this:

Ok, the light-blue are ruff position adjusting, for the moment, i would not tamper with them (jet).
Yellow is the lens tangential position screw.
Red are the pot’s (potentiometers). One of them is for DVD and other for CD beam intensity adjusting.

That’s about it :slight_smile: You can tamper with these screws for hours and maybe there would be a succes - but there is no way to know.

For furter progress i need help.

The holy gral of my quest is the service manual of Pioneer 109,110 and especially 111. With osciloscope you can measure the ‘quality’ of signal and so detect if you’re on the right way to the optimal position and laser intensity, but where to pick up and what kind of signal should there be?

The second step should involve testing the drives in another computer to make sure the problem isnt initiated by drivers or software…

I’ve tried that and on the other pc is the same thing. Not to mention that my friend’s 111 works just fine on my pc, but mine doesnt. I’m pretty much sure that it’s laser beam focus/position involved.
Electronic and electric components do wear out and their performance and have relative higher or smaller tolerance regardless they’re the same tipe and markings (resistance, capacitance, dinamyc caracteristics do change also over time, even if the product stays intact, properly preserved, that only can slow down the aging process, but not stop). That’s why there are potentiometers in the first place (in factory to calibrate each drive because the tolerance of components) and later they can be used to compensate for aging process.

I’d be very grateful if someone can tel me where to pin the scope and indirectly measure the reflected signal of the beam. Then i’d be able to track the signal as you adjust the potentiometers. I hope that someone know that bite of information, otherwise i’ll go and experiment :slight_smile:

Anything else is about the same as walking in the dark.

One question…

If the player can read and write DVD:s but not CD:s, couldn’t it just be that the CD laser diode has burnt out, but the DVD diode is still working?

I think this thread would be useful for you. :wink:

How can i be shure that laser diode is burnt out?

I could measure the diode if i knew where she is or where on the circuit board are ‘‘wires’’ that lead to the cd laser diode…

That’s a great thread, thank you very much Chef!!!

I dont think that cd diode is burned out… it’s like my rw detects the cd for the moment, but lost it the next…
i’m tampering with ‘fine’ tangential position on 111, i’ll post the results soon :slight_smile:

Ok, after some experimenting i can say:

If the drive is standing in its normal position so that the cables are on the right and the black or white begining of the drive on the left, those two potentiometers are as follows:
- upper one is for DVD
- the one that is down is for CD

If you turn them clockwise, you are decreasing beam intensity (it seems to me) and counter-clockwise you increase beam intensity, both for DVD and CD.

If the drive can read any of the media, i think i can say that the lens are in good position - if then adjusting of potentiometers for the non-readable media doesnt help - the laser diode for that media is probably burnt.

Pioneer 109,110 and 111 are simple to adjust, but NEC 3520 is different, it has two pairs of potentiometers under the lens (not right by (upper) side of lens like pioneer). so far i didnt experiment with these, i’m dead tired of that for now :slight_smile:

If anybody knows whitch of these is for what, please do tell!

What about Toshiba SD-M1802? Is it possible to make the proper adjustments?

I’m shure that’s possible - u just need to find the potentiometers and figure out how to adjust them (in what direction to turn them to increase laser beam intensity).