trying to fix a TV

T

the snake

[H]ard|Gawd
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not sure where to put this thread, so mod please move if need be...........

a friend gave me a 32" samsung LCD that will not power on, so i figured i would try and see if i can get it running.

when ya try and power it up, the screen is black and it goes into sleep mode i think.

anyways i have a service manual for it, but am confused on what this symbol is for, in the red arrow, is that a capacitor or what am i looking for ?

i am trying to find some test points to check standby voltage and this is the first one the manual says to check.

see attached jpg please :)

wayisthis01.jpg
 
This is a very common problem with Samsung LCD's just google it. A very easy repair if you know how to solder, and that it didn't fry other components.
 
Yep , common problem with lots of brands.

Just start looking for the swollen/popped electrolytic capacitors.
 
I fixed LCDs for awhile as a hobby, they can be rather frustrating. My general approach was to do a complete dis-assembly down to the panel itself to check for broken backlights and loose wiring first. After making sure nothing is physically damaged, the wonderful process of elimination takes over for the power supply, logic board, and inverter(s). From my experience if you're getting any sign of power (LED lights up etc.) the power supply is typically working. The inverter is usually the next suspect as logic boards don't particularly fail all that often, and when the logic board is failing, the tv usually powers up.

One last tip: watch where you put your fingers and screwdrivers. :)
 
Crispy002 said:
I fixed LCDs for awhile as a hobby, they can be rather frustrating. My general approach was to do a complete dis-assembly down to the panel itself to check for broken backlights and loose wiring first. After making sure nothing is physically damaged, the wonderful process of elimination takes over for the power supply, logic board, and inverter(s). From my experience if you're getting any sign of power (LED lights up etc.) the power supply is typically working. The inverter is usually the next suspect as logic boards don't particularly fail all that often, and when the logic board is failing, the tv usually powers up.

One last tip: watch where you put your fingers and screwdrivers. :)
Click to expand...

when i try to power it up, the red LED near the power switch goes on and then off, if i remember correctly.

okay, i have the board marked as to which caps go where, i will pull one at a time and label the caps as to were they go on the board, also i can see better what caps i need to purchase after they are removed.

seem like a good plan to you all ?

http://i249.photobucket.com/albums/gg203/tommy2fingers/board-001.jpg
 
Make sure whatever capacitors you replace are replaced with low-ESR type capacitors. ESR is equivalent series resistance, which limits how fast the capacitor will charge and discharge. If the capacitor is part of a switched voltage regulation circuit, having a part with too high an ESR will cause noise in the power rail and can seriously b0rk your signal.

I used Radio Shack caps in an AKAI set and can't use 1080p at 60Hz because the timing goes shithouse and lines jitter like a squirrel on crack.
 
Not a good plan (yet).

First, get yourself a DMM, turn the set on and check all your voltages on that SMPS board. on the left of that picture should be a 24v that is important. Next on the right side of that pic is a bigger connector, I believe that board pins 1 and 3 should both have 5v. look at the silkscreen on the board. there should be 2x 12v lines and one more 5v line. Finally the top right of the board is backlight control which is 5pin connector. When the set is one and working pins 1 and 5 should both have 5volts which tells the backlight to be on.

Alternatively you can unhook that 5pin connector from the main board side. run a piece of wire from pins 1 and 5 and power the set up. this will force the backlight to come up and let you know if the inverter is working proper.

The caps on that board don't look physically bad, but if they are bad you are only concerned about the ones you listed at 1-7.


I'd like to get a better idea what the set is doing though.

When plugged in standby should be steadyly on. during power one it typically blinks and when finally on it will go out. Do you see a flicker of backlight come up during startup? Also after a few minutes will the standby light happen a few more times? Also when on can you bring up the menu or see any on screen display?
 
My Samsung LCD went out last year, only 2.5 years old. It would come on then off.

I just threw it out. I should have tried to fix it but I didn't realize it was possible at the time.
 
plunger said:
My Samsung LCD went out last year, only 2.5 years old. It would come on then off.

I just threw it out. I should have tried to fix it but I didn't realize it was possible at the time.
Click to expand...

Most of the dead lcd's I have repaired were caps, only one was actually the a bad logic board.
 
Most I have seen are ONLY bad caps. Occasionally though the bad caps will take a part or two with them. Usually a surface mount fuse. The worst I have seen are when small value caps go bad and fail shorted. This usually then toasts the board.
 
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