Samsung 2253bw black screen

[budm]

Re: Samsung 2253bw black screen

You can use 1K resistor between 5V line and pin8 (do not connect the logic board)

[e3gsr]

Re: Samsung 2253bw black screen

super, thank you just need to find a 1k resistor now lol.

[budm]

Re: Samsung 2253bw black screen

1.5k, 2k, 2.2k may work

[Rtech]

Re: Samsung 2253bw black screen

super, thank you just need to find a 1k resistor now lol.

But hopefully interesting...and fruitful at the end.

[e3gsr]

Re: Samsung 2253bw black screen

0.98k? found one in the garage just got to relieve the board of it now lol.

[e3gsr]

Re: Samsung 2253bw black screen

ok got it off the board just need to solder some tails onto it and have a drink before I try it. never know i could be nil by mouth within the next ten minutes lol.

[e3gsr]

Re: Samsung 2253bw black screen

nope still no backlight just ticking from the board now but no squealing like i had before.

[budm]

Re: Samsung 2253bw black screen

Check the voltage on that green fuse, proably is going up and down right now.

[e3gsr]

Re: Samsung 2253bw black screen

yes it is between 5 and 9 volts. Anything else I can try?

[rogfanther]

Re: Samsung 2253bw black screen

it should still be around 13-15V. What does it measure without the resistor, and with the resistor connected ?

[Rtech]

Re: Samsung 2253bw black screen

What is the part codes on q202 and q203 ?? and what condition do they seem to be in cosmetically ? looks like something is pulling the voltage down when you apply the enable 3v, and they are the most likely suspects.

[e3gsr]

Re: Samsung 2253bw black screen

the resistor i have just fitted? if so, without, it reads 14v, with it ranges between 5 and 9 volts when i flick the power on the backlights flash then it dies again and the board just ticks, do you think there is a short somewhere causing it to shut down?

[Rtech]

Re: Samsung 2253bw black screen

see Post 31 ??

[e3gsr]

Re: Samsung 2253bw black screen

yep got the wife looking now as i cant see it lol.

[e3gsr]

Re: Samsung 2253bw black screen

ok can only find q202 but i think it is z6? with 2a written at right angles to that. does that make sense at all?

[budm]

Re: Samsung 2253bw black screen

14V is low for 22" monitor. Please see attached picture for some testing you need to see, the soldering works on the caps look pretty bad also. I expect the lamps to flash ON for seconds at least with 14V.

[Rtech]

Re: Samsung 2253bw black screen

Q202 and Q203 i thought were the two 8 pin chips on the bottom, they drive the Inverter transformers..or am i having a Blonde moment ??

[e3gsr]

Re: Samsung 2253bw black screen

right just checked them and i am getting on U202 with pins on right shorted
from the top
244.6 ohms
439.8k
0.1 ohms
5.4 ohms

on q203 i get the same only on pin 4 i am reading 161.5ohms
I will go and resolder the caps now.

[e3gsr]

Re: Samsung 2253bw black screen

Q202 and Q203 i thought were the two 8 pin chips on the bottom, they drive the Inverter transformers..or am i having a Blonde moment ??

i think you are on about U202 and U203 they are 8 pin chips.

[budm]

Re: Samsung 2253bw black screen

The 8-pin chips on the bottom side are Dual MOSFET's
"244.6 ohms
439.8k
0.1 ohms
5.4 ohms"
Are these the resistance reading that I asked to check by leave one probe on any one of the pins on the right side of the chip (pins on the right are connected together) as shown in my redlined picture, then another probe on each pin top read the resistance? If that's the case, then you have bad chip (shorted).
Can you read the numbers on them?