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Aktuelle Version von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well![br]
[br]
James Stuart at: https://de.ifixit.com/Antworten/Ansehen/169538/What+components+need+replacing+on+the+Logic+board
“[br]
I don't mean to offend anyone but you all seem to have missed the blatantly obvious and that is the LED backlight array.
LEDs age, and as such the amount of light that is emitted reduces. The LEDS in the LM240WU6 panel are made by Lumileds which is a subsidiary of Philips who in turn produced the panel under license from LG. The LEDs used are LXML-PWN1-0120 which should be operated at a forward voltage of between 3.0V & 3.6V @ 350mA and have a stated 39000 hours of life.
LEDs operate in constant current mode that is the current through the device is adjusted by altering the voltage across it. In low current LED applications this done with a simple resister. In high powered applications this is done with a controller chip such as the HV9982. Most high powered applications work as a closed loop system, that is they monitor the current flowing in the LED string and adjust the voltage across the string accordingly. The circuit Apple adopted does just that, it monitors the voltage developed across a low ohm resister in the bottom of the LED string and adjust the PWM signal to the HV9982 that will adjust the voltage to the LEDs. The suggested fix above of applying 3.3V to the PWM input will remove this feedback and will apply maximum voltage across the LEDs and is likely to result in damage to the LEDs and driver circuit.
What most people are experiencing is the backlight driver circuit shutting down due to it reaching an overvoltage point as it tries to pump more current through the aged LEDs.
(picture in the original post)
The above plot shows the current through each LED with a forward voltage of 3.3V. As you can see there is a lot of variation (LED 1 shows as 0mA), none of them get near the 350mA that they should.
Conclusion, the only long term way to fix this problem is to replace the LED string as a whole or at least the weaker LEDs. The individual LEDs are available from DigiKey but they will prove difficult to replace as they are surface mount and are tied to a heat sink back plate. An alternative is to retrofit a low voltage backlight replacement string, they are available on eBay for as low as £4. These will require a 12V supply and will need to be turned on and off manually.
"
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
This looks like the original one:[br]
https://www.alibaba.com/product-detail/-LED-WHITE-LXML-PWN1-0120_1600336451323.html?spm=a2700.exhibition_search.normal_offer.d_image.7ec0oxdAoxdATt
[image|2485712]
+From the original LumiLed Datasheet, the SMD LED component footprint:
+
[image|2485715]
[br]

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well![br]
[br]
James Stuart at: https://de.ifixit.com/Antworten/Ansehen/169538/What+components+need+replacing+on+the+Logic+board
“[br]
I don't mean to offend anyone but you all seem to have missed the blatantly obvious and that is the LED backlight array.
LEDs age, and as such the amount of light that is emitted reduces. The LEDS in the LM240WU6 panel are made by Lumileds which is a subsidiary of Philips who in turn produced the panel under license from LG. The LEDs used are LXML-PWN1-0120 which should be operated at a forward voltage of between 3.0V & 3.6V @ 350mA and have a stated 39000 hours of life.
LEDs operate in constant current mode that is the current through the device is adjusted by altering the voltage across it. In low current LED applications this done with a simple resister. In high powered applications this is done with a controller chip such as the HV9982. Most high powered applications work as a closed loop system, that is they monitor the current flowing in the LED string and adjust the voltage across the string accordingly. The circuit Apple adopted does just that, it monitors the voltage developed across a low ohm resister in the bottom of the LED string and adjust the PWM signal to the HV9982 that will adjust the voltage to the LEDs. The suggested fix above of applying 3.3V to the PWM input will remove this feedback and will apply maximum voltage across the LEDs and is likely to result in damage to the LEDs and driver circuit.
What most people are experiencing is the backlight driver circuit shutting down due to it reaching an overvoltage point as it tries to pump more current through the aged LEDs.
(picture in the original post)
The above plot shows the current through each LED with a forward voltage of 3.3V. As you can see there is a lot of variation (LED 1 shows as 0mA), none of them get near the 350mA that they should.
Conclusion, the only long term way to fix this problem is to replace the LED string as a whole or at least the weaker LEDs. The individual LEDs are available from DigiKey but they will prove difficult to replace as they are surface mount and are tied to a heat sink back plate. An alternative is to retrofit a low voltage backlight replacement string, they are available on eBay for as low as £4. These will require a 12V supply and will need to be turned on and off manually.
"
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
This looks like the original one:[br]
https://www.alibaba.com/product-detail/-LED-WHITE-LXML-PWN1-0120_1600336451323.html?spm=a2700.exhibition_search.normal_offer.d_image.7ec0oxdAoxdATt
[image|2485712]
+[image|2485715]
+
[br]

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well![br]
[br]
James Stuart at: https://de.ifixit.com/Antworten/Ansehen/169538/What+components+need+replacing+on+the+Logic+board
“[br]
I don't mean to offend anyone but you all seem to have missed the blatantly obvious and that is the LED backlight array.
LEDs age, and as such the amount of light that is emitted reduces. The LEDS in the LM240WU6 panel are made by Lumileds which is a subsidiary of Philips who in turn produced the panel under license from LG. The LEDs used are LXML-PWN1-0120 which should be operated at a forward voltage of between 3.0V & 3.6V @ 350mA and have a stated 39000 hours of life.
LEDs operate in constant current mode that is the current through the device is adjusted by altering the voltage across it. In low current LED applications this done with a simple resister. In high powered applications this is done with a controller chip such as the HV9982. Most high powered applications work as a closed loop system, that is they monitor the current flowing in the LED string and adjust the voltage across the string accordingly. The circuit Apple adopted does just that, it monitors the voltage developed across a low ohm resister in the bottom of the LED string and adjust the PWM signal to the HV9982 that will adjust the voltage to the LEDs. The suggested fix above of applying 3.3V to the PWM input will remove this feedback and will apply maximum voltage across the LEDs and is likely to result in damage to the LEDs and driver circuit.
What most people are experiencing is the backlight driver circuit shutting down due to it reaching an overvoltage point as it tries to pump more current through the aged LEDs.
(picture in the original post)
The above plot shows the current through each LED with a forward voltage of 3.3V. As you can see there is a lot of variation (LED 1 shows as 0mA), none of them get near the 350mA that they should.
Conclusion, the only long term way to fix this problem is to replace the LED string as a whole or at least the weaker LEDs. The individual LEDs are available from DigiKey but they will prove difficult to replace as they are surface mount and are tied to a heat sink back plate. An alternative is to retrofit a low voltage backlight replacement string, they are available on eBay for as low as £4. These will require a 12V supply and will need to be turned on and off manually.
"
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
-[image|2135341][image|2485712]
+[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
This looks like the original one:[br]
https://www.alibaba.com/product-detail/-LED-WHITE-LXML-PWN1-0120_1600336451323.html?spm=a2700.exhibition_search.normal_offer.d_image.7ec0oxdAoxdATt
-[image|2485712][image|2485713][br]
+[image|2485712]
+
+[br]

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well![br]
[br]
James Stuart at: https://de.ifixit.com/Antworten/Ansehen/169538/What+components+need+replacing+on+the+Logic+board
“[br]
I don't mean to offend anyone but you all seem to have missed the blatantly obvious and that is the LED backlight array.
LEDs age, and as such the amount of light that is emitted reduces. The LEDS in the LM240WU6 panel are made by Lumileds which is a subsidiary of Philips who in turn produced the panel under license from LG. The LEDs used are LXML-PWN1-0120 which should be operated at a forward voltage of between 3.0V & 3.6V @ 350mA and have a stated 39000 hours of life.
LEDs operate in constant current mode that is the current through the device is adjusted by altering the voltage across it. In low current LED applications this done with a simple resister. In high powered applications this is done with a controller chip such as the HV9982. Most high powered applications work as a closed loop system, that is they monitor the current flowing in the LED string and adjust the voltage across the string accordingly. The circuit Apple adopted does just that, it monitors the voltage developed across a low ohm resister in the bottom of the LED string and adjust the PWM signal to the HV9982 that will adjust the voltage to the LEDs. The suggested fix above of applying 3.3V to the PWM input will remove this feedback and will apply maximum voltage across the LEDs and is likely to result in damage to the LEDs and driver circuit.
What most people are experiencing is the backlight driver circuit shutting down due to it reaching an overvoltage point as it tries to pump more current through the aged LEDs.
(picture in the original post)
The above plot shows the current through each LED with a forward voltage of 3.3V. As you can see there is a lot of variation (LED 1 shows as 0mA), none of them get near the 350mA that they should.
Conclusion, the only long term way to fix this problem is to replace the LED string as a whole or at least the weaker LEDs. The individual LEDs are available from DigiKey but they will prove difficult to replace as they are surface mount and are tied to a heat sink back plate. An alternative is to retrofit a low voltage backlight replacement string, they are available on eBay for as low as £4. These will require a 12V supply and will need to be turned on and off manually.
"
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
-[image|2135341]
+[image|2135341][image|2485712]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
+
+This looks like the original one:[br]
+https://www.alibaba.com/product-detail/-LED-WHITE-LXML-PWN1-0120_1600336451323.html?spm=a2700.exhibition_search.normal_offer.d_image.7ec0oxdAoxdATt
+
+[image|2485712][image|2485713][br]

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

-Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
+Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well![br]
+[br]
+James Stuart at: https://de.ifixit.com/Antworten/Ansehen/169538/What+components+need+replacing+on+the+Logic+board
+
+“[br]
+I don't mean to offend anyone but you all seem to have missed the blatantly obvious and that is the LED backlight array.
+
+LEDs age, and as such the amount of light that is emitted reduces. The LEDS in the LM240WU6 panel are made by Lumileds which is a subsidiary of Philips who in turn produced the panel under license from LG. The LEDs used are LXML-PWN1-0120 which should be operated at a forward voltage of between 3.0V & 3.6V @ 350mA and have a stated 39000 hours of life.
+
+LEDs operate in constant current mode that is the current through the device is adjusted by altering the voltage across it. In low current LED applications this done with a simple resister. In high powered applications this is done with a controller chip such as the HV9982. Most high powered applications work as a closed loop system, that is they monitor the current flowing in the LED string and adjust the voltage across the string accordingly. The circuit Apple adopted does just that, it monitors the voltage developed across a low ohm resister in the bottom of the LED string and adjust the PWM signal to the HV9982 that will adjust the voltage to the LEDs. The suggested fix above of applying 3.3V to the PWM input will remove this feedback and will apply maximum voltage across the LEDs and is likely to result in damage to the LEDs and driver circuit.
+
+What most people are experiencing is the backlight driver circuit shutting down due to it reaching an overvoltage point as it tries to pump more current through the aged LEDs.
+
+(picture in the original post)
+
+The above plot shows the current through each LED with a forward voltage of 3.3V. As you can see there is a lot of variation (LED 1 shows as 0mA), none of them get near the 350mA that they should.
+
+Conclusion, the only long term way to fix this problem is to replace the LED string as a whole or at least the weaker LEDs. The individual LEDs are available from DigiKey but they will prove difficult to replace as they are surface mount and are tied to a heat sink back plate. An alternative is to retrofit a low voltage backlight replacement string, they are available on eBay for as low as £4. These will require a 12V supply and will need to be turned on and off manually.
+
+"
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
-
-=== Update (08/08/2020) ===
-# '''Everlight ELSH-J11N(X) seems to be a pretty close to identical product to these Lumileds.'''
-The best match in alibaba that I found to replace the LEDs.[br]
-LED lighting ELSH-F91N1-0CPGS-C4500 SHUEN NEUTRAL WHT 4500K 2SMD
-
-https://www.alibaba.com/product-detail/LED-lighting-ELSH-F91N1-0CPGS-C4500_1600084289857.html?spm=a2700.galleryofferlist.0.0.28b23d977FkGg3

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
=== Update (08/08/2020) ===
# '''Everlight ELSH-J11N(X) seems to be a pretty close to identical product to these Lumileds.'''
+The best match in alibaba that I found to replace the LEDs.[br]
+LED lighting ELSH-F91N1-0CPGS-C4500 SHUEN NEUTRAL WHT 4500K 2SMD
+
+https://www.alibaba.com/product-detail/LED-lighting-ELSH-F91N1-0CPGS-C4500_1600084289857.html?spm=a2700.galleryofferlist.0.0.28b23d977FkGg3

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
=== Update (08/08/2020) ===
-# '''Everlight ELSH-J31NX seems to be a pretty close to identical product to these Lumileds.'''
-# The closest I found in alibaba:[br]
-https://www.alibaba.com/product-detail/LED-lighting-ELSH-J31M3-0CPGS-D2700_1600084363156.html?spm=a2700.galleryofferlist.0.0.4608db60PfD8Ef
-#
+# '''Everlight ELSH-J11N(X) seems to be a pretty close to identical product to these Lumileds.'''

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
=== Update (08/08/2020) ===
# '''Everlight ELSH-J31NX seems to be a pretty close to identical product to these Lumileds.'''
+# The closest I found in alibaba:[br]
+https://www.alibaba.com/product-detail/LED-lighting-ELSH-J31M3-0CPGS-D2700_1600084363156.html?spm=a2700.galleryofferlist.0.0.4608db60PfD8Ef
+#

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
=== Update (08/08/2020) ===
-# '''Everlight ELSH-J11NX seems to be a pretty close to identical product to these Lumileds.'''
+# '''Everlight ELSH-J31NX seems to be a pretty close to identical product to these Lumileds.'''

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
=== Update (24.07.2020) ===
[image|2164951]
I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.
+
+=== Update (08/08/2020) ===
+# '''Everlight ELSH-J11NX seems to be a pretty close to identical product to these Lumileds.'''

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
=== Update (06/14/2020) ===
[image|2135344]
[image|2135343]
[image|2135340]
[image|2135341]
[image|2135342]
+
+=== Update (24.07.2020) ===
+[image|2164951]
+
+I found the Lumileds to order, but investing like 130CHF (approx. 130USD) is a bit too much for the moment, for this project. Besides I tried unsoldering with hot air station that I ordered a few of those LEDs and it is indeed possible but quite tedious, so perphaps not worth the time and money.

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
=== Update (06/14/2020) ===
I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.
+
+=== Update (06/14/2020) ===
+[image|2135344]
+
+[image|2135343]
+
+[image|2135340]
+
+[image|2135341]
+
+[image|2135342]

Status:

open

Bearbeitet von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!
+
+=== Update (06/14/2020) ===
+I got some more equipment and returned to fix my 24” cinema display. So in the meanwhile the display was working like every second day by chance. In the meantime I found a donor cinema display with the same defect. Backlight shutdown after a flicker of light.
+
+So I decided to open my display again and took out the led strip totally to test it. I only have a 30V regulated power source so I could test the whole led array (60Volts needed). But I tested the leds individually and they seemed to at least light all one by one with significant differences in luminousity. Now I wonder how to find out which ones should I replace without desoldering all of them. I desoldered 4 of them with my new hot air station, but it is quite tedious to get one out.

Status:

open

Ursprünglicher Beitrag von: Robert Nawfal ,

Text:

Update (2018/09) My display is still up and running after changing the Capacitors, but I reckon this is only coinsidense. I would advice you to have  a look at James Stuart comment/explanation below. I think it makes the most sense and explains the cause of the problem well!

Status:

open