Re: Samsung LA26R71BA cannot power up
Hi vinceroger69,
Your dim bulb tester is a great suggestion. And btw, when there is no more shorts in the circuit, the TV will not turn on if it is connected to it. I have to disconnect the dim bulb tester before the TV can turn on.
john_doe
Senior Member
Last Activity: 12-21-2016, 03:44 AM
Joined: 04-03-2013
Location: Malaysia
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Re: Samsung LA26R71BA cannot power up
Got the 18nF cap.
After replacing this cap, the TV started to work normally.
After all our troubleshooting, the actual culprit is the CM808.
Thank you very much budm, vinceroger69 and dick_barton. You guys rock!Last edited by john_doe; 12-03-2016, 04:56 AM.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
So should i replace this cap and then do the voltage checking or put back this cap and do the voltage checking?lLeave a comment:
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Re: Samsung LA26R71BA cannot power up
I have removed CM808. So you think this cap is ok?
I will have to resolder this cap back and check on the main filter cap and CMN802 24v tomorrow.Last edited by john_doe; 12-02-2016, 08:34 AM.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Based on other thread, i checked CM808 out of circuit and it is 6nF. On the capacitor it is printed as 2J 183J SIC 460S. On the schematic, it is stated as 183 630v. The other thread said it is 18nF 630v.
What is the actual specs of this cap and could it be faulty?Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Hi vinceroger69 and dick_barton,
I want to play safe and connected the dim bulb tester.
With the 1k ohm resistor connect from standby to ps_on, the bulb glows half brightness continuously.
These arè the voltages at CNM801:
Pin1 = 4.2vdc
Pin7 = 9.6vdc
Pin8 = 9.6vdc
Pin13 = 5.4vdc
Pin14 = 5.4vdc
Pin15 = 5.4vdc
Pin16 = 5.4vdc
Pin19 = 9.6vdc
Pin21 = 9.6vdc
Pin22 = 9.6vdc
Thank you guys for helping me.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
hi budm,
Where should I start to check?Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Hi,
I am still only getting 5.2vdc standby and no PS_ON.
Any idea where should I check?Leave a comment:
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Re: Samsung LA26R71BA cannot power up
I have replaced BD801S bridge rectifier and NT811S thermistor.
Beside these two, I have also replaced QP801S mosfet and ICP801S earlier.
With the dim bulb tester connected, when i power up, the bulb will light up with about half brightness for 2 secs and then it will be off. When i removed the dim bulb tester, there is no shorts.
Only the red light at the front of the TV is lighted. It is the same as the beginning of the problem.
With the main board disconnected, the voltage of the big filter...Leave a comment:
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Re: Samsung LA26R71BA cannot power up
DP804 (out of circuit) = 0.492vdc 1 way, the other way = OL
DZP801 (out of circuit) = 0.678vdc 1way, the other way = OL
Both are good.
I have ordered the bridge rectifier and the thermistor.
Are there anythings I should check while waiting for the parts to arrive? I hope I don't blow more parts.
A big Thank you to dick_barton, vinceroger69 and budm for all the help given.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
RP816 = 99.5k ohm
RP817 = 7 ohm
RP818 = 15 ohm
DP804 (in circuit) = shorted
DZP801 (in circuit) = 0.9v 1way, 0.6v the other way. I know it is not accurate to test in circuit.
CP803 = 2 M ohm and the value is dropping.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
I confirmed only NT811S burnt up and fuse FB801S is still ok.
Bridge rectifier pin1 to 3 shorted, pin 2 to 4 also shorted.
QP801S:
Pin2 (pos) to pin3 (neg) = OL
Pin2 (neg) to pin3 (pos) = 0.454vdcLeave a comment:
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Re: Samsung LA26R71BA cannot power up
QP801S: Resistance
Pin3 (pos) to pin2 (neg) = 192.3k ohm
Pin3 (neg) to pin2 (pos) = 280k ohm
Pin3 is shorted to heatsink. Strange?l
Resistance of RP819 = 0.4 ohmLeave a comment:
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Re: Samsung LA26R71BA cannot power up
Just to be clear, only NT811S blew up. The fuse FP801S is ok.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
The original mosfet is the TO-220F type. The mosfet I replaced is the FCPF11N60NT and it is the TO-220F with the plastic tab. It is not shorted to the heatsink.
I attach the datasheet....Last edited by john_doe; 11-21-2016, 06:32 PM.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
DP801 and DP802, both 0.413vdc one way, the other way is OL.
BD801S:
Pin1(pos) to pin2(neg) = OL
Pin1(neg) to pin2(pos) = 0.453vdc
Pin2(pos) to pin3(neg) = 0.453vdc
Pin2(neg) to pin3(pos) = OL
Pin3(pos) to pin4(neg) = OL
Pin3(neg) to pin4(pos) = 0.453vdc
BD801S looked faulty. Am i right?Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Resistance
Pin1 to 2 = 8.3M ohm
Pin2 to 3 = 5.6M ohm
Pin3 to 4 = 12.25k ohm
Pin4 to 5 = 22.4k ohm
Pin5 to 6 = 22.1k ohm
Pin6 to 7 = 99.5k ohm
Pin7 to 8 = 106k ohm
The thing on pin4 is solder.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Yes, i replaced QP801S.Leave a comment:
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Re: Samsung LA26R71BA cannot power up
Pic of ICP801S...Leave a comment:
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Re: Samsung LA26R71BA cannot power up
For QP801S,
Positive Negative
Pin 1 to 2= 290k ohm
Pin 1 to 3= 99k ohm
Pin2 to 3 = 400k ohmLast edited by john_doe; 11-20-2016, 07:29 AM.Leave a comment:
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