This is a 19 " HP which powers on OK but the backlights will not light. I tested these lights and they test OK I replaced all the cap on the power board with same results. I am looking at retiredcaps sticky and am thinking that it may be a transistor but I am rather intimidated by these because I am not sure how to identify them for example how can one determine the start/stop transistor? The signalling transistors? etc. This board has quite a number components with the Q designation but look different. Some has E,C,B and some has S,G,D and than there are some with 8 contacts like the 2 (P607 BD5A18)
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Re: HP no backlight
Originally posted by davg View Post(P607 BD5A18)
http://pdf1.alldatasheet.com/datashe...D/AOP607L.html
Measure to see if S1-G1, S1-D1 and D1-G1 are shorted. Do the same for the "2s" and report your readings.--- begin sig file ---
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Re: HP no backlight
Thanks retiredcaps assuming pin 1 is indicated with a dimple the readings are as follows
Q 104
S1-G1-30 m ohms
S1- D1- 4 M Ohms
G1-D1- 0L
S2-G2-69 M OHMS
S2-D2-0L
G2-D2-0L
Q105
S1-G1-29 M Ohm
S1-D1- 20 M Ohm
G1-D1- 0L
S2-G2-38 M Ohm
S2- D2-0L
G2-D2-0L
where I get a reading the reading is continually decreasing?Last edited by davg; 11-02-2012, 04:01 PM.
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Re: HP no backlight
None of those mosfets are shorted.
On the connector to the main/logic board (which is cut off in the picture), is there a legend? If yes, is there a pin that says BL_ON or something. The main board generates the BL_ON and it should be > 2.0V DC.--- begin sig file ---
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Re: HP no backlight
What is the model number of this HP? Can you zoom out a little bit so I can see the whole board, both sides? By the way, do you see the lights even flash on at all?Last edited by budm; 11-02-2012, 07:58 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
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Re: HP no backlight
Originally posted by davg View PostYes there is as follows BRL ON_OFF, +5 volts, +5 volts, GND, GND, GND, +12 Volts. The voltages on these pins read 1.57v, 0v, 5.22v, 5.22v, 0v, 0v, 0v, 12.24v. You say non of these mosfets are shorted!! what kind of readings would I get if they were? (just learning)
ON_OFF = 0V
I'm not 100% sure if BRL is backlight. The "R" is confusing me. Additionally, ON_OFF could be the backlight on/off command.
I define a short as anything less than 30 ohms. AFAIK, there is no industry agreed upon value.--- begin sig file ---
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We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
Please do not post inline and offsite as they slow down the loading of pages.
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Re: HP no backlight
The model # is HP-VS17 I will upload pictures in the morning. I have it apart now but I can't be sure if it flashes or not but if it does its quicker than the eye. When plugged in the blue power light comes on than goes to amber. I don;t see any flash of the backlights but I can see the image with a bright light.
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Re: HP no backlight
Originally posted by retiredcaps View PostBRL = 1.57V
ON_OFF = 0V
I'm not 100% sure if BRL is backlight. The "R" is confusing me. Additionally, ON_OFF could be the backlight on/off command.
I define a short as anything less than 30 ohms. AFAIK, there is no industry agreed upon value.
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Re: HP no backlight
BRI is brightness. ON_OFF, then, is your backlight on/off. It is 0V, then the main/logic board is not generating it.
Check the voltage regulators on the main/logic board. My sig file has a how to guide.--- begin sig file ---
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Please do not post inline and offsite as they slow down the loading of pages.
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Re: HP no backlight
Post a picture of the main board as well.--- begin sig file ---
If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.
We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
Please do not post inline and offsite as they slow down the loading of pages.
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Re: HP no backlight
Since the LED is AMBER, then that make sense why the ON_OFF is 0V. If the main board does not sense the video signal from the PC, it will turn off the inverter and the power to the LCD T-CON board. So check the regulators on the main board as suggested by retiredcaps.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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Re: HP no backlight
Originally posted by budm View PostIf the main board does not sense the video signal from the PC, it will turn off the inverter and the power to the LCD T-CON board.--- begin sig file ---
If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.
We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.
Please do not post inline and offsite as they slow down the loading of pages.
--- end sig file ---
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Re: HP no backlight
Here are the pictures that budm requested and with the unit attached to a pc the blue light stays blue but there is no flash of the backlights at all. I am hearing a humming sound on the power board when everything is hooked up. Is this normal? I have to do some reading before I start testing the regulators.
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Re: HP no backlight
The readings on the two regulators I304 and I305 are as follows:
I304
AIC line 1
1084-33PM line 2
328GC line 3
pin #1- 0V
pin#2- 3.29v
pin#3- 4.9v
I305
1117 line#1
-18PE line#2
91OCT line#3
pin #1 - 0v
pin#2 - 1.79v
pin#3 - 3.29
pins numbered left to right with long pad north
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Re: HP no backlight
Your voltage regulator readings look good. Here's what I think the problem is:
On your photo of the logic board, what is the part number for I308? It's the 3 terminal device right above the 10-wire wiring harness. If it's something like MAX809/810, then it's a reset controller. If yes, with power off, use your soldering iron to lift the VCC and RESET pins off the circuit board. Power up the monitor to see if you get an image. Note: failure of this controller has caused the same problem on various acer models.
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Re: HP no backlight
So when the LED turns blue with connection to running PC, do you now get >3VDC at the ON/OFF PIN? If you do, then we need to go back and troubleshoot the inverter circuits.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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