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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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CD Laser - Last Chance or Last Rites
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 |
#2
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"N Cook" 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 |
#3
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Cherry red? Is this a dvd player?
Mark Z. "N Cook" wrote in message ... 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 |
#4
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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" wrote in message ... "N Cook" 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 |
#5
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"N Cook" 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 ? 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" wrote in message ... "N Cook" 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. |
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