Samsung 245BW Dead

[CraigR]

Samsung 245BW is dead with no power light or anything. I have read the other posts on this model however it seems the common ones have a different power board then what I have (BN44-00195A) so those fixes don't apply. I have good fuses and no visually bulged caps and I have 166v at the large cap but then no low side voltage. I also checked the larger diodes and pulled QP801S and checked and was also fine. not sure what to pull and check next.

[CraigR]

Re: Samsung 245BW Dead

Just pulled and checked QM802 and QM803 are fine and cm806 also ok and RM801 and that is supposed to be .22ohm and it's .16 but I doubt that's the problem. Also removed all glue.

[euromatlox]

Re: Samsung 245BW Dead

Best solution is use the other board (BN44-00173A), since it's more reliable and (usually) easier to fix. However user Toasty has some knowledge, which might be useful in your case - some careful work with smd components needed.

https://www.badcaps.net/forum/showth...t=18966&page=2

I once did '195A' repair using Toasty's advice (DZT851), but the board did function only about hour or two. In that board was also that 8008HFE voltage regulator shorted, which I had to replace also. After new failure I did change some caps too...but never tried that board again, I guess I still have it somewhere (might have some useful spare parts). I swapped '173A' board which has functioned without problems.

(Of course '173A' did have three 68 ohm resistors and some capacitors changed. I did replace also some other resistors, just in case.)

[Dumah Brazorf]

Re: Samsung 245BW Dead

Could be a cold joint. Reflow all, even the tinyest smd.

[budm]

Re: Samsung 245BW Dead

Samsung 245BW is dead with no power light or anything. I have read the other posts on this model however it seems the common ones have a different power board then what I have (BN44-00195A) so those fixes don't apply. I have good fuses and no visually bulged caps and I have 166v at the large cap but then no low side voltage. I also checked the larger diodes and pulled QP801S and checked and was also fine. not sure what to pull and check next.

So you do not have standby DCV at all?
All those parts you have tested are for the PFC Voltage booster and for the 12V/24V SMPS which will require the PFC to work first.
YOU need to check the stby power supply section first, need to get the P/N of that 7-pin mini dip IC to find out if it has VCC to run it check those 5 small lytic caps close by..

[CraigR]

Re: Samsung 245BW Dead

budm, sorry it took me so long to get back to this. I di a mock up where it's all connected and I do not get any DC voltage and the connector for 24v or 5.4v but on a couple legs of that 7-pin IC i did get a flux between 55-63volts. and on that IC is numbers A6159 then under that is SK841 and under that is 07DK.

[CraigR]

Re: Samsung 245BW Dead

Ok, just replaced the 7 pin IC and still no joy.

[budm]

Re: Samsung 245BW Dead

budm, sorry it took me so long to get back to this. I di a mock up where it's all connected and I do not get any DC voltage and the connector for 24v or 5.4v but on a couple legs of that 7-pin IC i did get a flux between 55-63volts. and on that IC is numbers A6159 then under that is SK841 and under that is 07DK.

Well, I still do not know the P/N of the IC to verify the VCC Voltage for the IC to run.
The reason you are getting the 55~63V reading is because you are using the chassis as the GND for your meter, right?
You are making DCV measurement in the DC PRIMARY side of the circuit, you cannot use chassis as the GND. REF., You have to use the negative leg of the main filter cap as the GND ref. for the meter.

[fzabkar]

Re: Samsung 245BW Dead

STR-A6159, Sanken, Universal-Input/13 or 16W Flyback Switching Regulators:

https://cdn.badcaps-static.com/pdfs/...cd00f00320.pdf
https://cdn.badcaps-static.com/pdfs/...a926aeb2d0.pdf

[CraigR]

Re: Samsung 245BW Dead

numbers on chip
A6159
SK841
07DK

[budm]

Re: Samsung 245BW Dead

STR-A6159 spec sheet.
Check the VDC between GND pin 3 and VCC pin 2, GND pin 3 and Startup pin 5.