Laser diode output lands?

buddha · 9th September 2005, 10:25 AM

The service manual to my dvd player says I have to
"short-circuit the laser diode output land" on the drive before disconnecting PCB flexi-cables.

As per this picture:

Afterwards, it says I should then "open the land".

What are these "lands"?
Why is it necessary to short them if the unit is unplugged?

Finally, what does it mean to "re-open" them? Am I meant to leave them short-circuited whilst the board is removed? How would I do this?

Thanks.

Extreme_Boky · 9th September 2005, 11:22 AM

You should solder the pins together - check the photo I attached. Do this before you remove the membrane ribbon cable (if you can rich the lands with ribbon cable attached to both mechanism and PCB!).

The new mechanism should come with both of these lands already soldered. Install the mechanism, insert both ends of your ribbon cable, and THEN remove the solder from both lands.

Use the antistatic wrist band all the time and connect it to the PCB's ground - one that the ribbon cable and mechanism are connected to.

Good luck,

Extreme_Boky

Extreme_Boky · 9th September 2005, 11:24 AM

replace 'rich' with 'reach'

buddha · 9th September 2005, 12:14 PM

Thanks, Boky,

What are these lands and why is it necessary to short them even if the player is unplugged from the mains?

caoauto · 9th September 2005, 04:31 PM

It is probably they don't want you to damage the SACD or CD reader part because probably that cause my player can not read the CD or SACD now. As I recall there is another guy have the same problem even those the power cable disconnect but there is charge in the caps still there, and the purpose of sordering together is to sure it is discharging. But I am only guessing, because I am waitting for my schematic to come yet.

buddha · 9th September 2005, 05:31 PM

Hmm, can't I just jumper these with a piece of wire and sticky tape?

alfsch · 9th September 2005, 08:10 PM

if iam right:
these pads are for static protection when handling or no connection, because laser diode is sensitive to static charge.
simply solder it together...this is a short at the laser and makes shure, you dont kill the diode.

dnsey · 10th September 2005, 05:05 AM

Quote:

Hmm, can't I just jumper these with a piece of wire and sticky tape?

You could, but tape is a pretty good static generator!
Just solder them - it's not a difficult job.

kevinkr · 25th September 2005, 02:56 PM

The solder link is to protect the laser diode from static. Using scotch tape or any plastic tape across those pads is a bad idea as the tape carries a charge as well.

Use a properly grounded anti-static strap and it is a good idea to use a solder iron with a grounded tip as well.

Kevin

9th September 2005, 10:25 AM	#1
buddha diyAudio Member Join Date: Apr 2005 Location: London	Laser diode output lands? The service manual to my dvd player says I have to "short-circuit the laser diode output land" on the drive before disconnecting PCB flexi-cables. As per this picture: Afterwards, it says I should then "open the land". What are these "lands"? Why is it necessary to short them if the unit is unplugged? Finally, what does it mean to "re-open" them? Am I meant to leave them short-circuited whilst the board is removed? How would I do this? Thanks.

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9th September 2005, 11:24 AM	#3
Extreme_Boky diyAudio Member Join Date: Dec 2003 Location: Sydney	replace 'rich' with 'reach'

9th September 2005, 12:14 PM	#4
buddha diyAudio Member Join Date: Apr 2005 Location: London	Thanks, Boky, What are these lands and why is it necessary to short them even if the player is unplugged from the mains?

9th September 2005, 04:31 PM	#5
caoauto diyAudio Member Join Date: Sep 2005	It is probably they don't want you to damage the SACD or CD reader part because probably that cause my player can not read the CD or SACD now. As I recall there is another guy have the same problem even those the power cable disconnect but there is charge in the caps still there, and the purpose of sordering together is to sure it is discharging. But I am only guessing, because I am waitting for my schematic to come yet.

9th September 2005, 05:31 PM	#6
buddha diyAudio Member Join Date: Apr 2005 Location: London	Hmm, can't I just jumper these with a piece of wire and sticky tape?

9th September 2005, 08:10 PM	#7
alfsch diyAudio Member Join Date: Jan 2002 Location: augsburg	if iam right: these pads are for static protection when handling or no connection, because laser diode is sensitive to static charge. simply solder it together...this is a short at the laser and makes shure, you dont kill the diode.

25th September 2005, 02:56 PM	#9
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	The solder link is to protect the laser diode from static. Using scotch tape or any plastic tape across those pads is a bad idea as the tape carries a charge as well. Use a properly grounded anti-static strap and it is a good idea to use a solder iron with a grounded tip as well. Kevin

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