Samsung Syncmaster 245BW

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245BW

I believe it's fine to post links here. Anyway a 5W resistor in that spot isn't going to get too hot but 70C is a low operation temp for a power resistor so you did good.

[antok86]

Re: Samsung Syncmaster 245BW

okay my monitor displays real quick then goes black. i can see my computer and the OSD real quick then it goes black and the blue light stays on. i got it torn down and i dont see any bulging caps or melted resistors. what can i check next/

[antok86]

Re: Samsung Syncmaster 245BW

okay my monitor displays real quick then goes black. i can see my computer and the OSD real quick then it goes black and the blue light stays on. i got it torn down and i dont see any bulging caps or melted resistors. what can i check next/

i took RB805, RB806, & RB807 out to measure and they all read at about 68 ohm

[PlainBill]

Re: Samsung Syncmaster 245BW

okay my monitor displays real quick then goes black. i can see my computer and the OSD real quick then it goes black and the blue light stays on. i got it torn down and i dont see any bulging caps or melted resistors. what can i check next/

Post pictures of the power supply / inverter board, or list the brands and series of the caps. The most likely cause of the problem is bad caps. I know you don't think any are bulging, but I've heard that story before.

The next suspect is the CCFLs. A broken wire, broken tube, or bad transformer will do it too.

PlainBill

[antok86]

Re: Samsung Syncmaster 245BW

[PlainBill]

Re: Samsung Syncmaster 245BW

Oh, Farkle!! I forgot to mention 'Do not post inline'. Retiredcaps will kill me.

I need a picture of the left 1/3 of the inverter, please. And as high resolution as possible. I really need to see the detail of at least two transformers and the board above and below them. Do not post it inline, attach it using 'Manage Attachments'.

PlainBill

[antok86]

Re: Samsung Syncmaster 245BW

it wont let me edit! =(

[PlainBill]

Re: Samsung Syncmaster 245BW

it wont let me edit! =(

I know. People were editing posts to change suggestions, etc. so Topcat put a 10 minute limit on editing.

ANYWAY, I got my head out of the nether regions and realized the very first post in the thread has adequate pictures of the inverter. I know you can take better, but that isn't necessary unless my instructions are too confusing.

Most boards have an orientation. In the case of the inverter, I call the edge with the connector to the power supply as 'down', the edge with the connectors to the CCFLs as 'up'. Conveniently, most of the printing is oriented in that direction.

When the board is oriented that way, T1 is located at the upper left, T12 at the upper right. I don't see any clear indication of numbering for the transformer pins, so I will arbitrarily say that the pin in the upper right corner of each transformer is pin 1. (Notice that pin is actually two pins soldered to the same pad.) That pad is connected to the CCFL connector. Pin 2 will be on the bottom right, and numbering continues clockwise. Pin 9 is another double pin and is at the upper left.

Pins 5&6 and 7&8 are obviously the ends of the primary winding. Pins 3&4 apparently do not connect to anything. Set your DMM on the 2K ohm scale and measure the resistance between pin 1 and pin 2 of T1. I would expect something in the 1000 ohm range. If it appears to be open, try between pins 1 and 3, 1 and 4, and 1 and 9. If you don't get any reading, increase to the 10K ohm range. If still no luck, try T2.

IF I was right about pins 1 & 2, measure the resistance between pins 1 and 2 of each transformer, and report the results. The readings should match to within 3%.

PlainBill

[lamouche1]

Re: Samsung Syncmaster 245BW

similar problem here with a 245bw for now no 24v no 5.3v rb805 reads open i'm digging in it for now to find something else burned qm802 reads good.

[lamouche1]

Re: Samsung Syncmaster 245BW

fixed i replaced all the 68ohms resistor by new ones everythings fine now thanks alot

[antok86]

Re: Samsung Syncmaster 245BW

Thanks bill I'll try to follow your instructions when I get home


Can I use 68ohm 1/5 watt resistor?

[PlainBill]

Re: Samsung Syncmaster 245BW

Thanks bill I'll try to follow your instructions when I get home


Can I use 68ohm 1/5 watt resistor?

@##%#$%@!!! Different problem!!! You have 'Two Seconds to black'. They have a dead 24V supply.

PlainBill

[antok86]

Re: Samsung Syncmaster 245BW

i know...but i took out my resistors to measure and i dont know if i can put the original resistors back in. And i can get 68 ohm 1/2 watt locally

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245BW

Well, the originals were 1 watt as the other members described. And they burned. What do you think will happen to 1/2 watt ones?

[antok86]

Re: Samsung Syncmaster 245BW

i know. People were editing posts to change suggestions, etc. So topcat put a 10 minute limit on editing.

Anyway, i got my head out of the nether regions and realized the very first post in the thread has adequate pictures of the inverter. I know you can take better, but that isn't necessary unless my instructions are too confusing.

Most boards have an orientation. In the case of the inverter, i call the edge with the connector to the power supply as 'down', the edge with the connectors to the ccfls as 'up'. Conveniently, most of the printing is oriented in that direction.

When the board is oriented that way, t1 is located at the upper left, t12 at the upper right. I don't see any clear indication of numbering for the transformer pins, so i will arbitrarily say that the pin in the upper right corner of each transformer is pin 1. (notice that pin is actually two pins soldered to the same pad.) that pad is connected to the ccfl connector. Pin 2 will be on the bottom right, and numbering continues clockwise. Pin 9 is another double pin and is at the upper left.

Pins 5&6 and 7&8 are obviously the ends of the primary winding. Pins 3&4 apparently do not connect to anything. Set your dmm on the 2k ohm scale and measure the resistance between pin 1 and pin 2 of t1. I would expect something in the 1000 ohm range. If it appears to be open, try between pins 1 and 3, 1 and 4, and 1 and 9. If you don't get any reading, increase to the 10k ohm range. If still no luck, try t2.

If i was right about pins 1 & 2, measure the resistance between pins 1 and 2 of each transformer, and report the results. The readings should match to within 3%.

Plainbill

readings from 2k setting
t1- 1191
t2- 1185
t3- 1178
t4- 1195
t5- 1189
t6- 1190
t7- 1181
t8- 1181
t9- 1191
t10- 1187
t11- 1180
t12- 1181

[antok86]

Re: Samsung Syncmaster 245BW

i noticed this...not sure what it is or if something was supposed to be there. monitor was never opened

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245BW

It looks like a pot covered with goop. Manufacturers frequently do that.

[PlainBill]

Re: Samsung Syncmaster 245BW

readings from 2k setting
t1- 1191
t2- 1185
t3- 1178
t4- 1195
t5- 1189
t6- 1190
t7- 1181
t8- 1181
t9- 1191
t10- 1187
t11- 1180
t12- 1181

The numbers indicate the transformers are probably not shorted.

What brand (and value) are the 4 yellow caps on the inverter?

PlainBill

[antok86]

Re: Samsung Syncmaster 245BW

The numbers indicate the transformers are probably not shorted.

What brand (and value) are the 4 yellow caps on the inverter?

PlainBill

says "SAM YOUNG" 220uf 35V

[PlainBill]

Re: Samsung Syncmaster 245BW

says "SAM YOUNG" 220uf 35V

Replacing those are the next step. From Digikey P12411-ND Panasonic EEU-FM1V221 would be my suggestion.

PlainBill