Samsung LN32A550 P3F

[Kokonut09]

I just picked up this LCD TV and the symptoms are as follows.

-Press power button
-sound comes on
-TV back light comes on for about a second or two
-TV goes black, power indicator is dark
-but! I press the power button once more, and plays the shutting down sound and red standby light comes on.

I did a quick scan of the power board and inverter board for bad caps but didn't find any that looked physically bad.

I was told that It could either be a bad inverter board, or a bad main board.

Any suggestions would be greatly appreciated.

I'll post pictures of the boards tomorrow.
Thanks.

[tom66]

Re: Samsung LN32A550 P3F

Samsung has the odd behavior of lighting the LED in standby and turning it off while running. So, it appears the TV is turning on and off normally, but the backlight is disappearing - this is known as "two seconds to black".

Causes include:
- bad caps
- bad transformers (likely)
- bad CCFLs

I highlighted bad transformers as Samsung TVs of this generation used a +24V supply and Darfon inverters (I think) which often fail. It is repairable by replacing the transformer.

[Kokonut09]

Re: Samsung LN32A550 P3F

Alright cool, how do I go about testing the transformer? I saw that you check in ohms, but when I tried that, I did not get any readings.

I'll post a picture of the inverter board when I get home today.

[tom66]

Re: Samsung LN32A550 P3F

Alright cool, how do I go about testing the transformer? I saw that you check in ohms, but when I tried that, I did not get any readings.

I'll post a picture of the inverter board when I get home today.

With a picture, we can suggest where to test... it's different for every transformer. Most will measure the same. Bad ones will measure values off by more than 3% either way.

[Kokonut09]

Re: Samsung LN32A550 P3F

Here we go, I hope these pictures turned out alright, I added pictures of the power board, not sure why, just in case?

[tom66]

Re: Samsung LN32A550 P3F

Test between these pairs of red marks.

All should measure the same or nearly the same.

Use the 20000 ohm (20k ohm) range.

[Kokonut09]

Re: Samsung LN32A550 P3F

First transformer
1848/1826

Second
1851/1883

Third
1846/1826

Fourth
1823/1802

[tom66]

Re: Samsung LN32A550 P3F

The average resistance is 1838 ohms and the allowable deviation is 55 ohms either way, so I think your transformers are okay.

Next step, are there any fuses on the inverter board?

[Kokonut09]

Re: Samsung LN32A550 P3F

Yes, there is 1 fuse on the bottom left in the picture you pointed on the transformers on. 125V/8A

[Kokonut09]

Re: Samsung LN32A550 P3F

I checked the fuses on the inverted board and power board and they checked out fine. I unplugged the inverted board and its showing the same symptoms.( minus the fact that the back lights don't come on) do you think that I should just go ahead and replace the inverted board?

[Kokonut09]

Re: Samsung LN32A550 P3F

Something else that i noticed. The blue glow on the tv when sitting idle turns off when the TV turns "on" and when I turn the TV off, the blue glow comes back.

[tom66]

Re: Samsung LN32A550 P3F

...The screen glows when the TV is on?

[Kokonut09]

Re: Samsung LN32A550 P3F

When I press the power button the TV glows for 2 seconds then goes black. What I was referring to was the little blue light Accent that's under the Samsung logo. I apologies for the miscommunication.

[richpart]

Re: Samsung LN32A550 P3F

Samsung's service site has these listed as a common failure. They dry up meaning they may not look physically bad or bubbled up.

Symptom:**The*TV*takes*longer*to*power*on*than*normal.**You*may*hear*several*clicks*while*the*TV*attempts*to*power*on.
*
Cause:*The*electrolytic*in*the*capacitors*on*the*power*supply*board*over*time*will*dry*out*causing*the*power*supply*to*shut*down*durig*its*initial*power*on*cycle.
*
Cure:*Refer*to*the*capacitor*cross*reference*guide*below*for*the*list*of*the*capacitors*that*should*be*replaced.
***
*
*
TV Model*
Side Label version*
Capacitor for Service*
Location
Spec
Part Number
LN32A550P3F
SQ01, SS02, AA03
CB852
25V 1000uF
BN81-02020A
CM851,CM852
35V 1000uF
BN81-03142A
CM853,CM858
25V 1000uF
BN81-02020A
CM859
25V 470uF
BN81-03132A

I'm also seeing a firmware update and downloading it for you as well. You will have to pm me with an email address for me to send all 3 files. They are too large to upload here based on the site limits. There is a bulletin, a firmware update and power supply diagram.

[richpart]

Re: Samsung LN32A550 P3F

The bulletin shows CM861 a blue 2200uf 10V as being the largest culprit here.

[Kokonut09]

Re: Samsung LN32A550 P3F

I replaced the Inverter board but nothing changed. Screen glows for a couple seconds and shuts off. I managed to push the source button to find my xbox, and there is still sound. I volume works as well.

richpart, I Dont see capacitor CM861 on my board.

[Kokonut09]

Re: Samsung LN32A550 P3F

Im gonna replace the caps and see what happens

[budm]

Re: Samsung LN32A550 P3F

So far I did not see any reports on the voltage readings from the power supply board.
I see that the power supply board has PFC Voltage booster, what DC voltage do you get on the large 450VDC cap when the TV is OFF and when the TV is ON?
do get steady 24VDC at the inverter board?

[Kokonut09]

Re: Samsung LN32A550 P3F

I'll check when i get home tonight. But i am getting 23.87V or so on the inverter board

[Kokonut09]

Re: Samsung LN32A550 P3F

Not exactly sure how to test it. All i did was touch red multimeter line to the positive side and got a reading of 220V on and 6.8V when its off. And you were talking about this cap correct?

And the inverter board gets 24.48 V.

I appreciate all the help thus far.