with inverter unplugged and main board plugged in the main filters go to 439 DCV then drops to 147 DCV.
439V is way too high, the cap is rated at 450V, so the PFC goes into shutdown and all you will get is 160V on the cap as expected when PFC is shutdown, It may have PFC Output Voltage sensing feedback issue.
Original OP PFC Voltage reading:
No scorch marks. 450v caps read 375v. Everyone is talking about standby mode; on this t.v. , when is off, the indicator light stays red and I have no readings. If I turn it on, it chimes, the light flashes and then goes off. After several minutes, it shuts off.
DP807 is connected to the CS pin4 f the PFC controller ic.
pin 4 CS
This pin is the input of the over-current protection comparator. The MOSFET current is sensed
using a sensing resistor and the resulting voltage is applied to this pin. An internal RC f ilter is
included to f ilter sw itching noise
https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
See schematic on page 18.
Pin 2:OVP
There are bunch of Resistor network for the PFC Output Voltage sensing, if the resistors go up in value that will cause the output to go high than what is intended.
If your pfc comes up for a second like you said, the circuit is likely working fine and is just not being told to turn on, check the VCC voltage for that circuit, it is usually controlled by a transistor (QM504) which could be controlled by an optocoupler (PCM802S).
Check your voltage on JP826, next to cap CM815, That voltage should be around 25 volts. If the voltage is there, check the voltage on QM504, (all three pins) and post it
https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
See schematic on page 18.
Pin 2:OVP
There are bunch of Resistor network for the PFC Output Voltage sensing, if the resistors go up in value that will cause the output to go high than what is intended.
This looks promising, did you test all those resistors?
BTW:
INV pin 1 is for the feedback for controlling the Boosted Output Voltage, the network resistors in this section are the one to check.
OVP pin 2 is the Over Voltage sensing that tells the circuit to go into shutdown if the Output Voltage is too high.
Just looking at this thread https://www.badcaps.net/forum/showth...ln46d550k1fxza and in post #8 (same fan7930) He was getting a pfc voltage pulse of 430v, Changing the ic solved his problem, so maybe thats the case here?
Ok, then it should be supplying VCC to the pfc ic pin 8, which is good, but it could be the pfc ic is shutting itself down, I posted in #215 (see how long hijack threads get) that someone else had a similar issue with high pfc voltage and the same ic number and it turned out to be the ic that was bad.
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