Re: Acoustic solutions LCD26761HDF no backlight
So that signal is the Positive, which is fed into the base in one of the two transistors in that section. We need to draw out how those two transistors and resistors are connected to pin 2 and pin 3 of the IC. That voltage must be used to turn on-off the Oscillator circuits of the PFC IC, that is the only thing I can think of.
Can you draw out the physical connections of that section, or the schematic of it?
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Re: Acoustic solutions LCD26761HDF no backlight
Budm just tried another reading..when black probe on primary side im getting a reading up & down from .346vdc to 1.254vdc with black probe still touching primary ground then red touching that point you highlighted it goes to 0.00vdc..thats on standby..when on black probe to ground primary goes to 1.430vdc & when red probe goes to 0.00vdc..thxLeave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
Hi budm as soon as i red probe that spot even without the black in primary ground area it still reads minus..the voltages do change with on & off but is minus?...thats why i asked if i should check again ..i left it overnight to do a fresh test & still minus?Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
That voltage reading does not make sense, minus? 1.486V. Do you have the Black probe on the ground connection as shown in my last PDF?Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
As long as you don't see a short it's probably okay.
Right now I would be looking at a new PSU from eBay: http://www.ebay.co.uk/sch/i.html?_fr...36&_nkw=17pw26 around £30.
As without a scope and extensive knowledge of switching power supplies you'll be spending a lot of time trying to find the problem.Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
G S
D being gate/sorce & drain B black probe & R red probe testing on ohms.
Testing on diode/resistance mode i got on Q813 R-S..BD 1 beep .523 & reverse OL all other combinations being OL
On Q814 1 beep .510 on same S-D & OL reverse..are these ok then tom so i can solder back in..thxLeave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
I think I figure out how the IC is being turn on/off, see the PDF.Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
Q813 markings P9NK50ZFP
GK1QC V6
CHN 842
All six cobinations where OL apart from B-D & R-S that was 2.702m
Q814 markings F M J05
FQPF
9N50C
Same results but B-D & R-S was 2.522m
These where measured out of circuit..how do you know if these are shorted thxLast edited by sienoki; 03-06-2012, 04:43 PM.Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
Which FETS tom Q813 & Q814? if so how do i test..is it out of circuit & red & black on the 3 pins..
Sorry for not knowing the terms for components as im totally new at this..im a slow learner..lolLast edited by sienoki; 03-06-2012, 02:54 PM.Leave a comment:
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Re: Acoustic solutions LCD26761HDF no backlight
From pin 2 & 3 i can see 2 traces..pin 2 trace goes to J159..pin 3 trace goes to 6801 smd resistor
http://i1068.photobucket.com/albums/...5/P1000892.jpg
http://i1068.photobucket.com/albums/...5/P1000894.jpgLast edited by sienoki; 03-06-2012, 01:53 PM.Leave a comment:
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this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even... -
I bought this p2210f dell monitor to fix. Schematic is the same as p2210.
Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered... -
Hello all,
Am trying to figure out this backlight issue with this A1990 Macbook Pro.
Tests performed:
There is no backlight even with a good screen.
Backlight IC is receiving the correct support voltages.
Fuse F8400 ok
Current sense resistor R8400 ok
Backlight IC is receiving 3.3V on enable pin.
Backlight IC receiving voltage from PPBUS_G3H, aprox 12.5V.
Backlight IC receiving 5V from PP5V_G3S
Backlight IC BKLT_SCL and BKLT_SDA both measure 0.545V diode mode to ground
I2C_BKLT_SCL and I2C_BKLT_SDA both measure... -
Hi this oldie had no backlight .after replacing caps on 24v rail ,
still no b/l this uses inverter type:1315 B1-16A,
im sure ive come across the same inverter in a samsung possibly le32r88bd ?
all t/x in board test ok ,so i fitted 15k and led to pin 4 of oz964gn ic
this allows protect to be temporary overridden.
b/l now comes on
but the left hand side of pic is gradually darker than the right side
i have the cct for the tv
but it does not have inverter cct.
i opened it up to inspect the ccfl tubes
and they dont have any... -
Hello, got an iPad Pro A2378 12.9 5th gen with no backlight. Got another test unit without screen, tested the screen, still no backlight with the test unit.
Figured out the backlight on the screen was bad, ordred a new backlight from mobilesentrix, *carefully replaced it* without damaging the lcd, oh well.
Final result, issue is still there, the screen has no back lights. So i'm back to square one, with 3 hours less and 100$ out, issue still on the screen.
The panel is still ok, i can see the apple in the middle of the screen when it kicks in, just no backlight.
Anyone...
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