Samsung LN-T4671F Power issue


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Samsung LN-T4671F Power issue

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RyanMoroz
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Sep 29, 2010, 12:11 AM

Post #1 of 18 (3334 views)
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Samsung LN-T4671F Power issue	Can't Post

Ok I know most people are going to read this and think, capacitors.

Simply, there is no relay click. The caps were bad, i replaced them with proper replacements. Then and now the TV will not give a replay click or anything. I have a 5.2v stand by on the 24 pin head but nothing else. No 13v, no 12v no 5.4v. I normally deal with plasma and this is the first samsung I have seen with more than a cap issue. Any advice would be great.

Main input is still good. as well as the inverters, and tcon. The issue I am sure is with the psu.

jts1957
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Sep 29, 2010, 12:24 AM

Post #2 of 18 (3331 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Is the power supply receiving a enable/turn-on voltage for the 13v, 12v & 5.4v? If not and you have a external supply, you could try enabling it yourself.

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RyanMoroz
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Sep 29, 2010, 12:31 AM

Post #3 of 18 (3327 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

I apologize for this but as I said I deal more with plasma than lcd.

Where would I test for that?

Also I did notice something else to ad. when I plug in the tv (currently apart on my repair table) the IR sensor board does a faint click every 3 seconds or so.

jts1957
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Sep 29, 2010, 12:41 AM

Post #4 of 18 (3323 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

The power supply generates 5 volts stand by to work the control board, remote receiver, etc. The rest of the power supply will only produce switched voltages when commanded by an "enable" signal (usually 3 to 5 VDC) from the microprocessor.
If the 13v, 12v & 5.4 volts are labeled, what are the rest of the labels from the control board?

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RyanMoroz
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Sep 29, 2010, 1:01 AM

Post #5 of 18 (3317 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

I assume you mean the 24 Pin that connects the Power Supply and main Input.

PIN
1-Power ON/OFF
2-NC
3-STB 5.2V
4~6 - GND
7~8 - 12v
9~12 - GND
13~16 - 5.4v
17, 18 - GND
19 - 13v
20 - GND
21~22 - 13v
23, 24 - NC

I can do some testing if you need any other info

(This post was edited by RyanMoroz on Sep 29, 2010, 1:04 AM)

RyanMoroz
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Sep 29, 2010, 1:05 AM

Post #6 of 18 (3312 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Also PIN 1 for ON/OFF gets no power

jts1957
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Sep 29, 2010, 1:10 AM

Post #7 of 18 (3311 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

In Reply To

Is the power supply receiving a enable/turn-on voltage for the 13v, 12v & 5.4v? If not and you have a external supply, you could try enabling it yourself.

1-Power ON/OFF

What happens here: when set is 1st plugged in?; when power button (remote or on set) is pushed?

If you have a 3 - 5 volt power supply source, monitor one of the switched PS sources as you apply test voltage to pin 1. Try hitting power button also during this test. If you get any positive action, control board most likely bad.

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Location: Far, Far Away

RyanMoroz
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Sep 29, 2010, 1:19 AM

Post #8 of 18 (3307 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Pin 1 when plugged in and cables are all connected

I plug in the TV, PIN1 reads 2.752
Waiting... hear the faint click from IR sensor and it jumps to 37.6 for a second then back down to 2.752

jts1957
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Sep 29, 2010, 1:23 AM

Post #9 of 18 (3305 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Can you "float" the pin 1 wire? Remove it from the plug and repeat test on Pin 1 wire from control board.

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Location: Far, Far Away

RyanMoroz
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Sep 29, 2010, 1:27 AM

Post #10 of 18 (3303 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Ok I Isolated the Pin 1 wire and now the voltages are a little different.

Instead of 2.75 it now reads at 5.2v normal jumps to 37.6 liek before still and then goes back to 5.2v

jts1957
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Sep 29, 2010, 1:32 AM

Post #11 of 18 (3299 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

If PS is only putting out 5vsb, where the heck is 37.6v coming from?

Do you have a external PS to inject your own 5v into pin 1 of PS socket?

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Location: Far, Far Away

RyanMoroz
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Sep 29, 2010, 1:37 AM

Post #12 of 18 (3297 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

sorry its not 37.6v its 37.6mv, posted wrong.

I am sorry to say I dont have an external.... will any 5v work? I can make a 5v dc external from a few old cell phoen charger cords suing the chases as a ground

jts1957
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Sep 29, 2010, 1:47 AM

Post #13 of 18 (3290 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Quote

now reads at 5.2v normal jumps to 37.6 liek before still and then goes back to 5.2v

Once it settles down to one or the other levels, will hitting the power button make it "cycle" as above each time it's pressed?
I'm wondering if that label for pin 1 has an "underline" under "ON" or "OFF?" (Active LOW)

Any stable 5v source should do.

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Location: Far, Far Away

RyanMoroz
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Sep 29, 2010, 1:51 AM

Post #14 of 18 (3287 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

There is a reset on the main input that yes when I press it, it cycles again immediately.

Also just in case it means anything, there is 2 fuses on teh PS. one of them is reading proper at 120 acv, the other is reading at .218 like its waiting. Not sure if that is ok or not. Just trying to cover all bases here.

I try the 5v source and see what happens.

RyanMoroz
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Sep 29, 2010, 2:01 AM

Post #15 of 18 (3285 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Ok tried it with a 5v external source, nothing changed. Had PIN 1 floated on the PS so no current from the main was going through PIN 1. Hooked up an external 5v, nothing. even took a measurement. it was going from 3.7 v to 5.2v at random this time. hit 4.3 and 4.8 a few times too i saw, but no change otherwise

RyanMoroz
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Sep 29, 2010, 2:06 AM

Post #16 of 18 (3283 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

Also just to ad, i am more trying to find otu if the issue is in the Power supply or something else. If I cannot repair it I can always order the part but I dont want to order the wrong part.

jts1957
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Sep 29, 2010, 8:38 AM

Post #17 of 18 (3269 views)
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Re: [RyanMoroz] Samsung LN-T4671F Power issue [In reply to]	Can't Post

That's why I'm attempting to fire up the power supply switched voltages with your own on/off signal. If we have good fuses, good caps, stand-by b-plus and a good enable signal, the switched voltages should be appearing. Unless we've missed something, the power supply is faulty. Wink

Edit: the enable signal from the sets control board, if I'm understanding your replies correctly, seems to be trying to cycle correctly.

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Location: Far, Far Away

(This post was edited by jts1957 on Sep 29, 2010, 8:41 AM)

RyanMoroz
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Sep 29, 2010, 4:31 PM

Post #18 of 18 (3260 views)
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Re: [jts1957] Samsung LN-T4671F Power issue [In reply to]	Can't Post

my god these are so different from plasmas.

That is perfect, I will spend a good part of the day testing the onboard components. (I dont have much better to do)

If you have any advice on where to look let me know. Ill start by tracing back the 5.4v, 12v and 13v.

Thanks again for all the help.

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