@joejonson
There has to be a voltage from the power board to the mainboard.
Perhaps when the new power board arrives, do not connect any cables to it except the AC power cable and check for voltage on the PD connector pins, presumably only the AC Det or STB pins
That way with no other cable connected to it, there's nothing that can damage the power board.
If there is none then the power board is not providing initial standby power to the mainboard for some reason
Can't imagine why especially if it happens with a 3rd power board, unless the board is shorting out to the chassis where it shouldn't be i.e. not at designated earth point on the board through a screw connection but somewhere else where it may be touching the chassis.
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@joejonson give us more information about this "and is completely dead". Are you saying that there are no signs of life? No power LED etc.? You said you have a new power board and "measured power supply". Where did you measure and what were the results? Do you get power to the center unit and did you check your AC cable? Your new power board is a RUNTKB116WJQZ what are the outputs on connector PD?
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
@joejonson,
What voltages are on PD-13 (AC Det) & PD- 24 (STB) of the power board?
Do you get the same voltages (if any) on the same pins of the PD connector on the mainboard?
crwdns2934271:0crwdnd2934271:0 jayeff crwdne2934271:0
@oldturkey03 sorry for the late response: Yes, no signs of life, I have 120V on the power cable pins, fuse is intact, but pressing of any buttons etc. does not light up LED etc. I saw in a video that if you unplug the main board (PD connector) the LEDs should be on, tried it nothing.
And yes, the part numbers and models of the power board are the same - don't think I overlooked something there.
@jayeff
I don't know if did anything wrong measuring the PD connectors but I didn't get any voltage there - had my multimeter on 20V DC put black on the housing of the TV and the red on on the pins and didn't get anything?! Was that correct?
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crwdns2934271:0crwdnd2934271:0 JoeJonson crwdne2934271:0
@joejonson
I was just looking at the info printed on the board next to the PD connector.
You can only access the odd numbered pins easily on the top of the board so pin 24 is hard to get to unless you unplug the cable, or remove the board from the chassis and support it whilst measuring the even pins on the underside
With most other brands the STB voltage is the standby voltage sent to the mainboard to indicate that power is available (the mainboard turns on the standby power LED)
There also being an AC Det pin (AC Detect?) might do the same thing. Either way there should be some voltage from the power board to the mainboard when the power is connected to the mainboard. The power board doesn't control the TV the mainboard does.
You may have to take a step back and ensure that there's AC power through the fuse on the power board
crwdns2934271:0crwdnd2934271:0 jayeff crwdne2934271:0
@jayeff Hi Jayeff, you reply fast :D - unfortunately there is no labeling of the pins on that board except of PNL12V, SGND, BU5V - the underside is also not labeled - so should I unscrew the board, take the connectors out and measure the Voltage between the two rows of connector pins with 20 VDC?
Thanks
crwdns2934271:0crwdnd2934271:0 JoeJonson crwdne2934271:0
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