Hi, i have a phillips 46pfl6606h tv here with no power. fuse blown, power ic blown, diodes blown due to excessive voltage. Ok now i have fully repaired the high side of the psu. As for the low side, on the standby voltage there suppose to be 3.3v but its showing 6v. Is that something i need to be worried about? According to the picture i attached, the marked diode was blown, and it says 7.5v zener diode, so i replaced with 7.5v zener diode. Unless its a 3.3v zener diode? Even i measured at the photo coupler leg it measured 6v.
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higher standby voltage on a phillips tv power supply
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Re: higher standby voltage on a phillips tv power supply
If that Zener d103 is blown it means the 300V is dump into the IC when it shorted out,
Did you verify that the opto PC101 and D104 are still OK?
Also, the meter and the battery of the meter iare OK?
If it is truly 6V output, do not leave it connected to the main board for now until it is verified.
LNK362 SMPS IC.Attached FilesNever stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Re: higher standby voltage on a phillips tv power supply
Originally posted by budm View PostIf that Zener d103 is blown it means the 300V is dump into the IC when it shorted out,
Did you verify that the opto PC101 and D104 are still OK?
Also, the meter and the battery of the meter iare OK?
If it is truly 6V output, do not leave it connected to the main board for now until it is verified.
LNK362 SMPS IC.
These are the components that was shot. Now high side seems to be ok though. Butttttttt, 3.3 is turning on the high side.Last edited by DjKrish; 07-22-2020, 01:27 AM.
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Re: higher standby voltage on a phillips tv power supply
That 7.5V Zener is the correct value, if you look at the internal circuit of the SMPS IC pin 3 (BP), the IC already has the internal 6.3V Zener to clamp down the output of the internal 5.8V regulator output, basically that external 7.5V is connected in parallel with internal 6.3V Zener so that external 7.5V is not really needed for the circuit to function, it is just and added protection.
At this point it looks like the power supply is not regulating.
What did you replace the OPTO PC101 with?
What Voltage do you get when measure between the two leg of the OPTO on the LED side?
What Voltage do you get when measure between the two leg of the OPTO on the Photo-Transistor side?
Is C107 tested good?
Please attach good clear hi-res of the whole top and bottom side of the power supply board for us to look at.
Did anyone else work on this board before you?Last edited by budm; 07-23-2020, 07:42 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Originally posted by budm View PostThat 7.5V Zener is the correct value, if you look at the internal circuit of the SMPS IC pin 3 (BP), the IC already has the internal 6.3V Zener to clamp down the output of the internal 5.8V regulator output, basically that external 7.5V is connected in parallel with internal 6.3V Zener so that external 7.5V is not really needed for the circuit to function, it is just and added protection.
At this point it looks like the power supply is not regulating.
What did you replace the OPTO PC101 with?
What Voltage do you get when measure between the two leg of the OPTO on the LED side?
What Voltage do you get when measure between the two leg of the OPTO on the Photo-Transistor side?
Is C107 tested good?
Please attach good clear hi-res of the whole top and bottom side of the power supply board for us to look at.
Did anyone else work on this board before you?
What Voltage do you get when measure between the two leg of the OPTO on the LED side? 0.098V
What Voltage do you get when measure between the two leg of the OPTO on the Photo-Transistor side? 4.58V
Is C107 tested good? yes its good
Please attach good clear hi-res of the whole top and bottom side of the power supply board for us to look at. Uploaded
Did anyone else work on this board before you? Definitely not.Last edited by DjKrish; 07-23-2020, 10:25 PM.
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Re: higher standby voltage on a phillips tv power supply
Originally posted by DjKrish View PostWhat did you replace the OPTO PC101 with? I replaced with PC817
What Voltage do you get when measure between the two leg of the OPTO on the LED side? 0.098V
What Voltage do you get when measure between the two leg of the OPTO on the Photo-Transistor side? 4.58V
Is C107 tested good? yes its good
Please attach good clear hi-res of the whole top and bottom side of the power supply board for us to look at. Uploaded
Did anyone else work on this board before you? Definitely not.
Check the LED of this OPTO in diode mode and in Ohm mode to see what it shows.
BTW, my request: "Please attach good clear hi-res of the whole top and bottom side of the power supply board for us to look at." I still need those full straight shots pictures of the whole board, your pictures only show partial pictures of the board.Last edited by budm; 07-23-2020, 11:37 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Originally posted by DjKrish View PostHi heres the photos. I tested the OP with analogue muiltimeter the traditional way, the led only has reading one side as usual whereby the transistor side no reading both way.
if you look at the schematic, it has resistors connected in parallel withe the LED of the OPTO so the meter should show resistance in both direction, look at the schematic.
You also need to test Voltages around U301, U301 may be bad and not turning on.Last edited by budm; 07-24-2020, 01:39 AM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Originally posted by budm View PostSo you do not have Digital meter? You should get one. Analog meter has low input resistance so it will affect the Voltage readings when trying to read Voltage in high resistance circuit.
if you look at the schematic, it has resistors connected in parallel withe the LED of the OPTO so the meter should show resistance in both direction, look at the schematic.
You also need to test Voltages around U301, U301 may be bad and not turning on.Last edited by DjKrish; 07-24-2020, 01:11 AM.
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Re: higher standby voltage on a phillips tv power supply
Can you look at your board and see if U301 is actually AZ431L (1.24V Adj shunt regulator) or it is TL431 (2.5V)?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Originally posted by budm View PostCan you look at your board and see if U301 is actually AZ431L (1.24V Adj shunt regulator) or it is TL431 (2.5V)?Last edited by DjKrish; 07-24-2020, 03:01 AM.
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Re: higher standby voltage on a phillips tv power supply
Originally posted by DjKrish View PostAt the board its AZ431L. So based on the voltage, do u think the regulator is shot?
Since we know that U301 is rated at 1.24V, that means the output of the power supply is designed to be at 3.3V.Last edited by budm; 07-24-2020, 03:43 AM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Originally posted by budm View PostYes.
Since we know that U301 is rated at 1.24V, that means the output of the power supply is designed to be at 3.3V.
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Re: higher standby voltage on a phillips tv power supply
Originally posted by DjKrish View PostOkay noted, thank you. will get it replaced and update he how it went. The part is not available anywhere in my country for now, need to order. While in the meantime, i read somewhere we can put a couple of zener diodes to perform a temp test to see if the circuit works as it should? Using zener diodes as a substitute to shunt regulator. Is that possible?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: higher standby voltage on a phillips tv power supply
Another suggestion, though I'm not sure how well it would work (or if at all):
Replace the AZ431L with a regular 431 (i.e. TL431) if that's all you have in stock. Then increase the value of the "lower" resistor in the resistive divider connected to the TL431 control/reference pin accordingly for 3.3V output. Looks like the lower resistor for that divider is R307.
The idea is that when you have 3.3V on the output of the PSU, the reference pin should now be at ~2.5V for the regular TL431.
I can't quite read the values on those SMD resistors completely, but looks like the lower resistor has "1201" printed on it - i.e. 1.20 KOhms? If that's the case, try a resistance of around 6.012 KOhms (or thereabouts) with a regular TL431. That should regulate to 3.3V output, more or less (may need to increase or slightly decrease the value of the "6.012"-KOhm resistor, to get desired output.) Putting together 10K, 22K, and 51K resistors in parallel should give about 6.058 KOhms, which might be just close enough... that is, provided R307 is indeed 1.20 KOhms. Please check before trying anything.Last edited by momaka; 07-25-2020, 02:21 PM.
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Re: higher standby voltage on a phillips tv power supply
Originally posted by momaka View PostAnother suggestion, though I'm not sure how well it would work (or if at all):
Replace the AZ431L with a regular 431 (i.e. TL431) if that's all you have in stock. Then increase the value of the "lower" resistor in the resistive divider connected to the TL431 control/reference pin accordingly for 3.3V output. Looks like the lower resistor for that divider is R307.
The idea is that when you have 3.3V on the output of the PSU, the reference pin should now be at ~2.5V for the regular TL431.
I can't quite read the values on those SMD resistors completely, but looks like the lower resistor has "1201" printed on it - i.e. 1.20 KOhms? If that's the case, try a resistance of around 6.012 KOhms (or thereabouts) with a regular TL431. That should regulate to 3.3V output, more or less (may need to increase or slightly decrease the value of the "6.012"-KOhm resistor, to get desired output.) Putting together 10K, 22K, and 51K resistors in parallel should give about 6.058 KOhms, which might be just close enough... that is, provided R307 is indeed 1.20 KOhms. Please check before trying anything.
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Re: higher standby voltage on a phillips tv power supply
Ok update time. Parts arrived. Fitted, checked for voltage, 3.3v was there perfectly. Hooked up to main board, standby light was there. Turned on tv, light was there, screen was there, then came a high pitch sound from power supply. I turned off the power, and then theres no standby light anymore. Unhooked the smps, tested for voltage again, its there 3.3v and nothing changed. What else could be wrong? How do i short the power supply on its own to turn it on, so that i can check all the output voltages? Suspect the high pitch sound came form the transformer thats connecting to the backlight.
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Re: higher standby voltage on a phillips tv power supply
Originally posted by DjKrish View PostOk update time. Parts arrived. Fitted, checked for voltage, 3.3v was there perfectly. Hooked up to main board, standby light was there. Turned on tv, light was there, screen was there, then came a high pitch sound from power supply. I turned off the power, and then theres no standby light anymore. Unhooked the smps, tested for voltage again, its there 3.3v and nothing changed. What else could be wrong? How do i short the power supply on its own to turn it on, so that i can check all the output voltages? Suspect the high pitch sound came form the transformer thats connecting to the backlight.
Try disconnecting the backlights LED connector and see what happen.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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