As mentioned above, the power goes down quickly from 394V to 374v then up and down with the same value, it usually is steady at these capacitors for everything to work flawlessly. It is very difficult to decipher what is written on this board the manufacturer has chosen white text on a bright yellow surface. Wondering what could be causing this power loop.
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POWER SUPPLY BN44-01056A Power fluctuation ON MAIN CAPACITOR
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Originally posted by stj View Postcould be the cap is shit or a PFC circuit problem
153,7uf
ESR 0.70 ohm
lost 1.4%
test on board
since they are 2 i think it is ok
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Originally posted by CapLeaker View PostIs that board working or do you have any problems beside the PFC being wonky? I do notice that some caps are not looking good (sleeve shrunk) like the first pic top left 4 capacitors for example.
a bit strange
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Originally posted by CapLeaker View PostWell the backlight LED's strings need current controlled high voltage DC somehow. It shouldn't be surprise.
about that voltage looping from the main capacitors it applies only when the mainboard is connected. Otherwise it is a steady 394v .
I think it says that there is something that is not right with the Mainboard so I leave the power supply alone .I wait for the mainboard that is on its way and see what happens or do you think there is something with it ?
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Hi all on this PS there is no full specification of the connector CNM801
1)GND 2) ANA_DIM
3) A13V 4) N C
5) A13V 6) PWM_BLU
7) A13V 8) POWER_ON
9) A13V 10) GND
11) GND 12) GND
the 13V is present 12.93V
there is no indication for 2,4,6 and 8 what value should be
For the STB and something named ON in the front of the CNM801 referring to 3 Jumper there must be 12.3V and 12.35V i do have 12.93V
CapLeaker with a load i used a a 12V car bulb on CNM 801 and no loop just 394V steady.
the question now is to where belong the 5V and 3.3V and a strange 2.4V in the bottom row of CNM801.
the PSU seems to be ok because when i disconnect the Mainboard the Backlight is on but still the Mainboard must have the right voltage from the PSU and that 2.4v is enigmatic
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Easy. Ana-dim is the dimming signal for the backlight from the main board to the PSU
PWM-BLU is the signal from the main board to the PSU to turn on the backlight
Power on = PSon comes from the main board and tells the PSU to turn all voltage rails on.
These values are you measured are o.k. The strange voltage probably belongs to the dim signal. You said pin 4 is N C or not?Last edited by CapLeaker; 04-23-2025, 07:34 PM.
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Originally posted by CapLeaker View PostEasy. Ana-dim is the dimming signal for the backlight from the main board to the PSU
PWM-BLU is the signal from the main board to the PSU to turn on the backlight
Power on = PSon comes from the main board and tells the PSU to turn all voltage rails on.
These values are you measured are o.k. The strange voltage probably belongs to the dim signal. You said pin 4 is N C or not?
then what is that ON 12.35 just in front of the contact CNM801
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As long as you take the main board off the PSU and "force" the PSU on and all the voltages are correct, it is safe to say you got a main board problem. We don't know what the TV model number is, nor we know what the TV main board does or doesn't do (symptoms why you think the main board is bad). Also the voltages you talk about, we haven't got a clue what pins they correspond to.
Some pins for example the dim pin voltage depends on what the back lights are set to. The PSon and BLon pin should be very close or the same as STBY voltage. Dim, PSon, BLon comes from the main board and tells the PSU what to do. The only voltage originating by the PSU and sent to the main board is STBY.
Maybe the main board has a short somewhere and dragging the voltage down. Who knows.Too hard to tell if we don't see the whole picture or don't get told the whole story.
Maybe make a new thread in the TV section, since you got main board trouble.
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