Hi guys i have been reading this forum with great interest the last couple of days, The reason I am here is I have a problem with a monitor I was given. The problem is the screen is permanently black, Back lights don't come on at all. I stripped it down and found bad caps so far I have replaced 4x820 1x330 and 2x1000. Lamps have been tested on another good monitor and are all working fine. When plugged in and turned on you can hear a feint squealing from the board but its hard to make out where it is coming from.Now I have 13.4v to my inverters but still no lighty. Anyone any ideas what to go for next before i give it .Apologies if I haven't put enough info if you need to know anything just ask. Forgot to say i am not totally green when it comes to electronics but i am no expert, so please go easy on me and any help to get my monitor working would be much appreciated.
Announcement
Collapse
No announcement yet.
Samsung 2253bw black screen
Collapse
X
-
Re: Samsung 2253bw black screen
Does it not even flash on for 1 second?
With it all connected and on, test voltages out on power board sockets see if they agree with any board markings for the socket.
Welcome to the forum-
We can sometimes help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.
Please do not post inline and offsite as they slow down the loading of pages.
Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049
https://www.badcaps.net/forum/attach...7&d=1280167246Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740
Comment
-
Re: Samsung 2253bw black screen
right just had 5 mins so i tested the board voltages. on the connector to the front panel i get
gnd-0v
key 2-1.82v
key 1-1.82v
led ranges from 2.7 to 0v obviously
3.3v-3.3v surprisingly enough
on the 12 pin connector i am getting
1-1.5v
2-14v
3-0v
4-0v
5-5.29v
6-5.29v
7-4.4v with led on
8-0.01 with led off jumps to around 1v when led on hard to measure accurately in time given
9-3.3v with led on drops when led goes off
10-2.7v with led on
11- around 1.8v with led on
12- around 1.8v with led on
does not flash on when turned on at all.
I have 14.9v at F301 and 13.4v at inverter connections not tested output for obvious reasons.
The led on the front panel flashes on and off even when connected to the pc.
I will take pics now and post them up.
Thank you for your help in trying to solve this matter.
Comment
-
Re: Samsung 2253bw black screen
Very good pictures -thanks have you tested the small green fuse in the middle of the power supply board.Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740
Comment
-
Re: Samsung 2253bw black screen
Can you test the voltage at each side of the F301 fuse use a ground screw for the black probePlease upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740
Comment
-
Re: Samsung 2253bw black screen
pin8 is for backlights on/off. 0v = off, I expect it to be >3vdc. It will go high when the monitor is first turn on, it will go low later if it does not detect the video signal from the PC, same thing for the voltage to the T-CON board on the LCD panel. If you remove (do not do it with the connector connected due to output drive may be at logic lo) that connector from the main board and use 1K resistor between pin8 and 5V, that will force the backlights to come on.
"on the 12 pin connector i am getting
1-1.5v
2-14v
3-0v
4-0v
5-5.29v
6-5.29v
7-4.4v with led on
8-0.01 with led off jumps to around 1v when led on hard to measure accurately in time given
9-3.3v with led on drops when led goes off
10-2.7v with led on
11- around 1.8v with led on
12- around 1.8v with led on"Last edited by budm; 08-29-2012, 09:41 AM.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
Comment
-
Re: Samsung 2253bw black screen
As suggested Pin 8 switches the Inverter on, and is usually about 3volts Dc from the Logic Board.What you can do is plug in your lamps,switch Power onto the Board leave the logic board not connected and the on off not connected,then apply 3v DC from a Bty between Pin 8 and one of the Ground connections, tha latter being a substitute for the Logic Board 3v, and the Lamps will normally light if all is well with the Power board ??
Comment
-
Re: Samsung 2253bw black screen
selldoor the voltage at both sides is a little over 94v is that right?
rogfanther yes all connected up and tested live.
budm and rtech i will try that now and let you know how i get on, That is if i dont end up in casualty lol. In fact I wont try it just yet until someone can confirm the voltage is correct on f301 at 94v.
Comment
-
Re: Samsung 2253bw black screen
I agree - the caps should be 25v and even upgraded to 35v would still have blown.Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740
Comment
-
Re: Samsung 2253bw black screen
Check your Voltmeter aging by measuring know good batteries, that voltage cannot be 94V for the inverter circuits, It should be around 15~20V for 22" Monitor.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
Comment
Comment