Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

[Giacomo Siffredi]

Hey All!

Here is my first troubleshooting post, so hopefully this is a fixable problem

Came into possession of a Samsung LN26A450C1D. Don't know much about the history except cosmetically the TV was well cared for. The first time I plugged it in and turned it on, there was the short Samsung power-on tune with the logo. Because I had no program source, there was no signal to replicate. I accessed the menu, but the print was jumping erratically and had a grayish ghost-like appearance. Turned it off. Turned it back on. This time the menu was inaccessible and there was just a dark gray screen, no functionality besides that. Turned it off. Turned it back on. Now there was horizontal streaking, no functionality besides that. Lastly I tried connecting an antenna to the TV, but that made no difference. I should also note that the on-set power button doesn't seem to work, so I am presently only able to use the remote control.

I am attaching a picture of the horizontal streaking. Please advise me what you think the problem may be and where I should begin looking to repair it. Thank you!

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Hey again,

I've examined the boards and observed no bulging or leaking capacitors and saw nothing else that indicated a burn-out or other suspicious cause of failure. The caps on the PSU were replaced per the Samsung class-action. Unfortunately, the TV still responds as I described earlier with the horizontal streaking, except it now is more responsive when the power button is depressed.

As before, when commands are delivered to the TV via the bezel or remote, the screen darkens as it receives the commands.

Is the more likely suspect in this case the t-con board or the main board? I could repair or replace either, but would like to know the more likely of the two to save some $ and time

[tom66]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

I would first reseat the cable between the main board and t-con.

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Hey Tom66,

I reseated that cable both ends and checked the integrity of the pins and ribbon cable. I also reseated the other two connections on the main board. Unfortunately, the screen display remains unchanged.

I should add that when I press "Menu", the streaked image gets considerably brighter. Pressing "Menu" again returns it to its normal brightness.

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Hey Guys,

I'm including some photos of the boards. Had to wait until today, as this has been the sunniest day in a while

What diagnostic and/or repair steps would you suggest I take next?

[tom66]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Check all voltage regulators.
https://www.badcaps.net/forum/showthread.php?t=22231

Check all power supply rails are stable.

Try feeding unit test patterns such as vertical bars to see how the noise propagates across the display.

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Hey Tom,

I have my digital multimeter and am ready to test. Before I do though, please verify that I will be grounding in the correct area and that these are the voltage regulators I should test. I am attaching a picture depicting the target areas on the boards.

[tom66]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Not quite... you've highlighted a few extra. See here:
https://www.badcaps.net/forum/attach...3&d=1346045483

Only test 3 pin + TAB. Do not test 5 pin + TAB.

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Okay, I only observed two such voltage regulators fitting the description and both were on the same board. Per the testing instruction link authored by Badcaps you provided to me earlier, these are the results:

First, both of these VRs are manufactured by Sipex.

IC1001 -> pcb designation
SPX1587AT -> line 1 of the IC
0830L0910 -> line 2 of the IC
pin 1 = 1.42
pin 2 = 2.62 (rapidly changing values)
pin 3 = 4.94
TAB = 2.68 (rapidly changing values)

IC1003 -> pcb designation
SPX1587AT -> line 1 of the IC
0830LC910 -> line 2 of the IC
pin 1 = 0.000
pin 2 = 0.19
pin 3 = 0.11
TAB = 0.19

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

I hope I reported the results correctly.

If so, it would appear to me from the test that IC1003 may be underperforming, and thus be faulty. Thoughts?

[budm]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

IC1001's output should be real steady since it is an output of the regulator, you need to check the Input filter cap that is connected to pin 3 (input pin) and the filter cap connected to the output pin (pin 2/ same as tab). IC1003 barely have any input voltage feeding it so you will not get the output voltage.

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Hi budm,

Are you referring to the caps on the PS board? That board was completely changed out. Otherwise, please direct me to the particular filter capacitors you are referring

[budm]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

I am talking about the caps for those two voltage regulators that you have posted the voltage readings on post #9

[Giacomo Siffredi]

Re: Samsung LN26A450C1D Powers On And Off... And That's Pretty Much It

Please bear with me, as I am somewhat of a novice at this , and I want to do this as right as possible.

I'm attaching a picture with the area circled which I believe you are advising me to check. Please verify if this is correct.

The PSU board with the capacitors was recently replaced, so I doubt the capacitors on that board would be bad.