I presently have a Quasar SQ5500U television with backlight failure but I am unable to find a service manual for this tv.Can anyone say where I can find this manual?
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Re: Quasar SQ5500u Led backlight failure.
A bit late to the party here, but I would like to add some input here. I got 3 of these family of TVs in and 2 were SQ5501u models. Only one PSU had bad caps, but the other two had multiple bad LEDs in the strips. Since the LCD panel itself isn't in a bracket for easy removal, you are going to need at least 2 sets of hands to avoid cracking it. Even then, expect a gamble. Wear gloves, have clean hands and have a nice soft, flat spot handy to place the LCD panel (I use a workbench with a shipping blanket over it).
Using a $20-25 LED tester will help a ton in locating the bad strips. Probably just going to combine 2 of the TVs into one working unit. Keep in mind that the wire lengths for the LED harness are really wonky and to check to make sure the sheet metal from the TV back isn't cutting into and shorting the LED wires out.
If there is a service manual for these things, I would be pretty surprised. Brands like LG, Sony, Samsung and other 'name brands' tend to have an interest in working with their technicians. With Quasar, I think they just do replacements instead of repairs. I could be wrong, but that seems to be the case with economy brands.
Don't let that deter you nonetheless.
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I have an Odyssey Neo G9 that I was working on for a separate issue. After removing the motherboard and putting it back a few times I noticed that the lights on the display have stopped turning on altogether. I was able to determine that when the middle section for the backlights is disconnected, then the left and right side turn on, indicating that the fault is obviously in that area.
After closely inspecting the mainboard I noticed that on the back side of it a few capacitors have been partially moved, one fully knocked off. I replaced the missing one with a new cap with the same...02-27-2025, 02:39 PM -
Problem
Fixing a dimming zone TV with LEDs not lighting up. Dimming zone circuit introduces added variable to diagnose LED and/or Dimming Zone Driver board? Some 1/2 rows of LEDs appears to be out in active dimming zone off AND some brightness flickering with active dimming zone high while playing changing video
Model & Board Pics
Conflicting Spec
Vizio indicate this TV has 10 dimming zones. However, LED strips and Zoned light driver connector suggest 12
https://www.shopjimmy.com/vizio-gj-2k1... -
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...
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