CD Laser - Last Chance or Last Rites

N

N Cook

Guest
Just checking to see if anyone knows of a 'CPR technique' .
Player would sometimes play a CD from cold but never a second CD.
The cherry red laser output would drop off over time just by sight.
To confirm a laser problem not controller problem I powered
up via external supply and droppers. Also monitored light output
with an IR phototransistor and ohms DVM.
Confirmed emission drop off and voltage at the laser dropping
from 2.64V to less than 2.5V. Gonner ?

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
 
Cherry red? Is this a dvd player?

Mark Z.


"N Cook" <diverse2@tcp.co.antyspahm.uk> wrote in message
news:Z6adnZK2HN0dRkfcRVn-pA@tcp.co.uk...
Just checking to see if anyone knows of a 'CPR technique' .
Player would sometimes play a CD from cold but never a second CD.
The cherry red laser output would drop off over time just by sight.
To confirm a laser problem not controller problem I powered
up via external supply and droppers. Also monitored light output
with an IR phototransistor and ohms DVM.
Confirmed emission drop off and voltage at the laser dropping
from 2.64V to less than 2.5V. Gonner ?

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
Click to expand...
 
"N Cook" <diverse2@tcp.co.antyspahm.uk> writes:

I had already established that the front end feedback circuit
to the laser power control was working if enough signal
got to its photodiode, so either a prob with this diode
or the laser. Last Rites ?
Click to expand...
Yeah, probably. :)

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.
"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6wpt0k92s4.fsf@saul.cis.upenn.edu...
"N Cook" <diverse2@tcp.co.antyspahm.uk> writes:

Just checking to see if anyone knows of a 'CPR technique' .
Player would sometimes play a CD from cold but never a second CD.
The cherry red laser output would drop off over time just by sight.
To confirm a laser problem not controller problem I powered
up via external supply and droppers. Also monitored light output
with an IR phototransistor and ohms DVM.
Confirmed emission drop off and voltage at the laser dropping
from 2.64V to less than 2.5V. Gonner ?

Probably but the method of powering it using resistors, etc., isn't a fair
test as the output power will drop off as it heats up. The driver in the
CD player is supposed to maintain the output power constant, but
apparently
isn't able to.
Click to expand...
 
"N Cook" <diverse2@tcp.co.antyspahm.uk> writes:

Just checking to see if anyone knows of a 'CPR technique' .
Player would sometimes play a CD from cold but never a second CD.
The cherry red laser output would drop off over time just by sight.
To confirm a laser problem not controller problem I powered
up via external supply and droppers. Also monitored light output
with an IR phototransistor and ohms DVM.
Confirmed emission drop off and voltage at the laser dropping
from 2.64V to less than 2.5V. Gonner ?
Click to expand...
Probably but the method of powering it using resistors, etc., isn't a fair
test as the output power will drop off as it heats up. The driver in the
CD player is supposed to maintain the output power constant, but apparently
isn't able to.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.


electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
Click to expand...
 
I had already established that the front end feedback circuit
to the laser power control was working if enough signal
got to its photodiode, so either a prob with this diode
or the laser. Last Rites ?

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6wpt0k92s4.fsf@saul.cis.upenn.edu...
"N Cook" <diverse2@tcp.co.antyspahm.uk> writes:

Just checking to see if anyone knows of a 'CPR technique' .
Player would sometimes play a CD from cold but never a second CD.
The cherry red laser output would drop off over time just by sight.
To confirm a laser problem not controller problem I powered
up via external supply and droppers. Also monitored light output
with an IR phototransistor and ohms DVM.
Confirmed emission drop off and voltage at the laser dropping
from 2.64V to less than 2.5V. Gonner ?

Probably but the method of powering it using resistors, etc., isn't a fair
test as the output power will drop off as it heats up. The driver in the
CD player is supposed to maintain the output power constant, but
apparently
isn't able to.

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ:
http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites:
http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the
excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above
is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.


electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
Click to expand...
 
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