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Old 05-12-2020, 01:00 PM   #1
diif
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Default BN44-00259A in a Samsung

This TV has had a previous repair that has not worked.
Capacitor CP810, the bridge rectifier and the fuse were damaged and the mosfet and FAN7530 were replaced out of caution.
The new bridge rectifier is a RS450M and the mosfet a 8N60C.

I have 340V across the main capacitor CP815, which doesn't seem right ? and there are no voltages on connector CNM802. Testing voltages on UM801S there is 340v on the drain but 0v on VCC.
I've checked all of the diodes and mosfets but I'm clearly missing something obvious and hope someone can point me in the right direction.
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File Type: pdf samsung_bn44-00259a.pdf (11.24 MB, 10 views)
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Old 05-12-2020, 01:52 PM   #2
R_J
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Default Re: BN44-00259A in a Samsung

What does'nt seem right about 340v on the main cap? That should be normal without the pfc working. Is the fuse FM802A good? UM801s is the standby ic that needs to be working before you will have any other voltages

Last edited by R_J; 05-12-2020 at 01:55 PM..
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Old 05-12-2020, 02:02 PM   #3
diif
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Default Re: BN44-00259A in a Samsung

I was expecting it to be higher or lower, or perhaps i'm just over thinking things..
Yes the fuse is good, I guess i need to track down the missing VCC for UM801S.
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Old 05-12-2020, 02:28 PM   #4
R_J
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Default Re: BN44-00259A in a Samsung

The ic provides its own vcc for startup (startup cell), I would check RM869 and see if it is open, I suspect the ic is bad. Once the ic is working, it's sustain vcc comes from TM801s (pin5) via RM890 & DM802,DM803. and charges CM804 which also supplies vcc to the other ic's via QB801
I would replace CM808 and CM804 as they are likely bad or on there way out

Last edited by R_J; 05-12-2020 at 02:32 PM..
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Old 05-12-2020, 03:20 PM   #5
diif
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Default Re: BN44-00259A in a Samsung

Thanks very much R_J, the resistor is ok, I've ordered the IC and caps, they should be here in a couple of days.
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