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...

Hello everyone

A friend gave me this Baykunl D80 DRO (Digital Readout) he uses for a lathe/milling machine. The LCD stopped working, shows no image or color whatsoever, but the backlight works.

When you power up, sometimes you can see a brief image but for like 1ms then it goes black. That kinda tells me the LCD is actually good and the issue lies elsewhere.

The board has:

• 1x ST STM32F103VET6 Micro-controller
• 1x RAIO RA8876LN4 LCD controller
• 1x Winbond W9864G6KH-6 SDRAM
• 1x Winbond W25Q128JV Serial Flash Memory
• 1x ATMEL ATMLH834 EEPROM
• 3x Texas

...

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...

Hi,

I liquid damaged a Macbook, disassembled it and spotted short near UP800. After desoldering it short was gone so I ordered the chip from https://aliexpress.com/item/1005005500396324.html.
Laptop is turning on, I can see something on the display if I flash strong light at it.
After replacing the chip, there is still no backlight. I measured components near the chip on both sides of the board again but everything seems fine.
Next I measured voltages near the chip, there is 5V, 1.2V, also 2.5V on LUXE_C_VDD (seems like it's internally generated by the chip, since...

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...