bad caps samsung 2253bw

[Daci]

So i had bad caps on my monitor. replaced them with new one's but it isn't working. I have picture but backlight isn't working, not for even a sec or two.
how to test pico fuse? is it same as other fuses? I removed it from board and tried to test it. when I put my multimeter on diode mode it isn't showing anything, same in 200 ohm range. but if I solder it where it should be on diode mode it shows some reading, in 200 ohm range it isn't showing anything...is that fuse ok or not ??

thank you, and sorry for my bad english

[kc8adu]

Re: bad caps samsung 2253bw

replace it.
a good one is less than 1 ohm.

[Daci]

Re: bad caps samsung 2253bw

one more question , how to check stm8309 ?

[retiredcaps]

Re: bad caps samsung 2253bw

one more question , how to check stm8309 ?

See my instructions in the mosfet section

https://www.badcaps.net/forum/showpo...4&postcount=19

[Daci]

Re: bad caps samsung 2253bw

I saw that, your instructions are for 3 pin mosfet and stm8309 is 8 pin ic with 2 mosfets inside...see datasheet ...

http://pdf1.alldatasheet.com/datashe...P/STM8309.html

[selldoor]

Re: bad caps samsung 2253bw

I saw that, your instructions are for 3 pin mosfet and stm8309 is 8 pin ic with 2 mosfets inside...see datasheet ...

http://pdf1.alldatasheet.com/datashe...P/STM8309.html

If you read it it also says

"Some mosfets are more than 3 pins. To test those, identify the part number and search for its datasheet. Once you find the datasheet, the pins will be designated source (S), gate (G), and drain (D). It will probably be documented as S1, S2, G1, G2, D1, D2.

Simply test

a) black on pin S1- red on pin G1 - record ohms
b) black on pin S1- red on pin D1 - record ohms
c) black on pin G1- red on pin D1 - record ohms

Repeat for the "2" pins. That is S2-G2, S2-D2, G2-D2."

[Daci]

Re: bad caps samsung 2253bw

sorry my mistake

u202...first stm8309

s1-g1 there is no reading (diode mode on multimeter 1458)
s1-d1 for brief moment there is some reading and then no reading
g1-d1 there is no reading (diode mode there is no reading)

s2-g2 there is no reading (diode mode 236)
s2-d2 less than 1 ohm
g2-d2 there is no reading diode mode 236)


same for u203...second stm8309

[selldoor]

Re: bad caps samsung 2253bw

Looks bad - I think you should take one off the board and re-test it.
I am assuming that "No reading" is a 1. or something that indicated out of range
the same as holding the probes apart.

When it is removed also test the pads at S2-D2 for short on the board.

[Daci]

Re: bad caps samsung 2253bw

yes you're right it is 1.

ok, I will try to change pico fuse first because it shows 1. when it is of the board, and it should be less than 1 ohm...can I replace that pico fuse with same value glass fuse ??

[selldoor]

Re: bad caps samsung 2253bw

As a temporary fix -yes If it ends up working then I would get the proper fuse. You need to be careful though when testing as if the glass fuse really blows it could spray tiny splinters. perhaps put tape on it?

[Daci]

Re: bad caps samsung 2253bw

ok thank you , I have experience with exploding glass fuse
will post results

[Daci]

Re: bad caps samsung 2253bw

changed fuse, and now power led is blinking all the time, and screen seams like it is going on and off but hardly noticeable ... what to do next...stm8309 ??

[selldoor]

Re: bad caps samsung 2253bw

Ithink so but wait for a second opinion if you want. Seems odd that both have the same problem

[Daci]

Re: bad caps samsung 2253bw

with stm8309 of the board

s1-g1 there is no reading (1. on multimeter)
s1-d1 there is no reading (1. on multimeter)
g1-d1 there is no reading (1. on multimeter)

s2-g2 159 ohm
s2-d2 less than 1 ohm
g2-d2 159 ohm

are they causing problem ??

[budm]

Re: bad caps samsung 2253bw

s2-g2 159 ohm
s2-d2 less than 1 ohm
g2-d2 159 ohm

Those readings are bad, you have bascially dead short between Source and Drain, and very low resistance between Source and Gate, Drain and Gate.

[budm]

Re: bad caps samsung 2253bw

Can we see good clear pictures of the board? It may be time to get new board.

[Daci]

Re: bad caps samsung 2253bw

this is best that I can do...

I only replaced caps and pico fuse is replaced with glass fuse...there isn't any burn mark on the board or on the any component

[selldoor]

Re: bad caps samsung 2253bw

Reason: edit: sorry for the big pics

Well why not remove them and add using manage attachments



EDIT - That is a lot better thanks

[Daci]

Re: bad caps samsung 2253bw

Is this good enough ?
I am just going to electronics store to get 2 stm8309...

edit. just bought stm8309 and readings on new one are :

s1-g1 there is no reading (1. on multimeter)
s1-d1 there is no reading (1. on multimeter)
g1-d1 there is no reading (1. on multimeter)

s2-g2 there is no reading (1. on multimeter)
s2-d2 there is no reading (1. on multimeter)
g2-d2 there is no reading (1. on multimeter)

does that mean that I have solved my problem???

[Daci]

Re: bad caps samsung 2253bw

yeeesssss problem was in that stm8309 ic's..replaced them and monitor works