another Samsung 2233

[tedmich]

bought from Dell in part because of its 3y warranty , but now Samsung says its 1y and back light failed at 2.5y

started to flicker a few days back, went black a few times and then re-fired. Now it flashes on and off and then goes totally black although display is still visible with a bright light.

board is different than most I have seen.
https://docs.google.com/open?id=0Bx4...E1OTZhZTBmYzVh

2 fuses (circled) at least not tiny pico units and test OK. Pulled all the SAMYOUNG caps and they all test ok by simple LCR meter. Pulled the inverter transformer and got 1.115k for both S1-2 and S3-4 but P2 is shorted to P3 (zero ohms) and should be closer to 0.2-1.0 I believe. I think the Samsung 2243 uses the same transformer and will order one. Have new Nichicons coming from mouser too.

[retiredcaps]

Re: another Samsung 2233

board is different than most I have seen.
https://docs.google.com/open?id=0Bx4...E1OTZhZTBmYzVh

We prefer pics hosted here so they are available for others in the future. Please use the manage attachment feature to upload and please do not post inline.

Pulled the inverter transformer and got 1.115k for both S1-2 and S3-4 but P2 is shorted to P3 (zero ohms) and should be closer to 0.2-1.0 I believe.

We rarely see the primary side fail. It is mostly the secondaries that fail.

When you touch your multimeter probes together, do you get 0.0 ohms?

[tedmich]

Re: another Samsung 2233

I may not have the resolution to measure 0.2ohms, my cheap DMM doesn't have a zero knob or calibrated leads but the primaries read identically (0.4 ohms) P2/P2, P3/P3 and P2/P3 so it looks like continuity to me. If shorted primaries are unheard of, secondaries which seem to be ok by R measurement are more common right? I plan to replace transformer regardless, and caps too. Bad CCFL is always a possibility too, unless I test with good inverter.

thanks for the tip on image hosting, I know of no other site which does this


this is Samsung P# BN44-00296A

[retiredcaps]

Re: another Samsung 2233

If you still have a problem after replacing the caps, report the DC voltages on the 12 pin connector to see if we have stable power.

[tedmich]

Re: another Samsung 2233

replaced all the (low voltage EL) SAMYOUNG caps, only $13 from Norvac, but not my favorite brands, which I was ready to order from Mouser for $3.

IT LIVES! THANKS ALL!

[retiredcaps]

Re: another Samsung 2233

IT LIVES!

Good job. Glad you got it working.

[tedmich]

Re: another Samsung 2233

postscript, I need a decent DMM which can measure low R values!

0.2 ohms does not equal 0 ohms!!

this can help:
http://www.keithley.com/data?asset=53682

think I'll make a 100mA CCS with an LT3092 and a couple precision resistors 2k/20k and a 9v battery