Re: Samsung 731BF no light
got it.thanks!
xifias
Member
Last Activity: 05-18-2025, 05:51 PM
Joined: 09-06-2012
Location: athens
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Re: Samsung 731BF no light
excuse me but could you please repeat your answer in lets say, basic english?
@retiredcaps
oh got it,but of course even if he had a service or smtg it would be very expensive such type of repair (post the screen,etc..)
just to mention,i oppened the panel and it has 2 lamps down on the bottom and 2 up.one lamp of the 2 on the bottom is black on the end,(usual for you'll say!).bad luck.i was hope to see some bad cable as you said.
now the screen works with the capacitor that...Last edited by xifias; 09-08-2012, 01:09 PM.Leave a comment:
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Re: Samsung 731BF no light
Alexanna is ebay dealer or so?Leave a comment:
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Re: Samsung 731BF no light
thank you once again.your help was priceless.do you know where to find one,or is it very pricey to repair.i live in greece.Leave a comment:
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Re: Samsung 731BF no light
so..i bought a small ccfl lamp.F6T5/D says.
i tried all the four outputs of the board.in the first position (cn302) the monitor stayed lit.in the second one (cn301) shut down.so did to the other two (cn303 and cn304) but with a little "hesitation" after 2-3 secs did fade away.
now?i need a new lamp?or 3 of them? :PLast edited by xifias; 09-07-2012, 11:18 AM.Leave a comment:
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Re: Samsung 731BF no light
thank you very much for your time.
check the pdf.the schem makes it little complicated with the numbering on the transformer,but i desoldered him from the board,and measured him,and visually from the bottom (its open) it is exactly as i describe it to you.2 secondaries that are connected through the R341.
thanks once again.Leave a comment:
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Re: Samsung 731BF no light
omg you have a serius collection there..and experience i suppose.
by the term "cap trick" i mean shortly what i described and above,the connection of a capacitor from the resistor to earth.recently i found that and onto the resistor in parallel does the same.according to the schem,that resistor (R341) looks like it "connects" the two secondaries of the transformer.can a resistor have and a capacitive behavior that is lost due to stress?
from a close look to the cables they seem good,but i was unable to open...Last edited by xifias; 09-07-2012, 09:09 AM.Leave a comment:
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Re: Samsung 731BF no light
some info is that in the input of the inverter is 14,29V (the schematic says 15) measured now that works (with the cap hooked on) and in off state (with the lamps off) goes up to 16,82V.
some guy also told me that with the cap trick i bypass some kind of built-in leakage detection of the inverter so it doesnt shuts down.
anyway can be the problem before the inverter on the smps part of the power supply?
i attach a much more cleaner schematic i found on pdf.
PS:i just saw that the cap also does the same...Last edited by xifias; 09-07-2012, 05:25 AM.Leave a comment:
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Re: Samsung 731BF no light
well hello again.
the blue 3kv caps on the end all seem ok.i've checked them with the ohm meter.also and some others that are smd have checked.
the lamps arent tested to another board.but with the "cap trick" stay on for at least 20 minutes.no heat no something weird,even though the cap was 100V rated,at a place that has 650V theoretically.
your interesting is very important to me.thank you again.Leave a comment:
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Re: Samsung 731BF no light
thank you for your reply.
yes it is the "2 second to black" problem yet now it became almost imediately.0,2 sec max. i suppose.so,i attached a picture that is taken right after i opened the screen.
the caps marked with red x are all changed with equals and higher volts some of them.
the childish draw with green on the top of the picture is where i connect the cap (and the voltmeter also) and it works.one end here other on the ground.
i checked diodes,resistors,smd diodes on the other side and...Last edited by xifias; 09-06-2012, 06:43 PM.Leave a comment:
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Samsung 731BF no light
hello
i have an lcd monitor,samsung 731bf that goes off from illuminocity almost imediately.i changed the bulged caps from the power supply board,yet the problem insists.i found accidentally that if the voltmeter is in paralel on the high voltage output,it manages to stay on and show picture normally.
i tried a 47nF/100V capacitor that laid around instead of the voltmeter and it worked also.
but i want a more confident solution.why is that happening?will it be dangerous or so?its not mine you see,its for a friend,and i wont be able to monitor it after i give it back....Last edited by xifias; 09-06-2012, 01:31 PM.
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