LG 42PC5D green light flashes three times and TV turns off.

[HarrySeaward]

Can anybody walk me through finding the faulty component?

When I hit the power button, the green light flashes three times and then the TV turns off, with the light going back to red.

There is a relay that clicks immediately upon pressing the power button and then clicks again when the TV turns back off.

[dick_barton]

Re: LG 42PC5D green light flashes three times and TV turns off.

It always help and is a good starter if you can post clear and well focused picture of your circuit boards along with any voltage testing you may have carried out on the power supply. Many reader will be unfamiliar with the set but knowing the circuit board part numbers along with any information gleamed from testing goes a long way towards a successful diagnosis.

[tvtimmy]

Re: LG 42PC5D green light flashes three times and TV turns off.

Probably bad capacitors on the power supply. Post clear pictures.

[HarrySeaward]

Re: LG 42PC5D green light flashes three times and TV turns off.

Photos

[dick_barton]

Re: LG 42PC5D green light flashes three times and TV turns off.

Follow the guide as given in this thread
https://www.badcaps.net/forum/showth...ghlight=42PC5D

You could also check the power supply voltages are all there.
Vs = 185V
Va = 60V
and the following
19V, 12V, 6V, 5V, 3.4V, Stby 5V

[HarrySeaward]

Re: LG 42PC5D green light flashes three times and TV turns off.

Follow the guide as given in this thread
https://www.badcaps.net/forum/showth...ghlight=42PC5D

Sorta having a hard time following the "guide" in that thread as OP generally ignored a lot of the suggested actions and otherwise it seemed to just be martino throwing out things to check but without any mention of what the ideal measurements should be, etc. For example, martino suggest checking some resistances and the OP responds talking about voltages. I'm not totally inept but I might just need a liiiiittle more specific/detailed steps to take because that thread is not laid out incredibly clearly lol.

But for starters, here are some measurements I did do.

Z-board connector P1:

• Vs <-> Gnd: 188.1kΩ
• Va <-> Gnd: 25.5kΩ

Y-board connector P3:

• Vs <-> Gnd: ∞Ω
• Va <-> Gnd: 25.5kΩ

19V, 12V, 6V, 5V, 3.4V, Stby 5V

These all seem fine.

You could also check the power supply voltages are all there.
Vs = 185V
Va = 60V

This is where things get odd.

First I measured these with everything connected. They both read 0v.

Then I unplugged the connector going from the power board to Y-board P3. First of all, when I turned the TV on with the connector unplugged it stayed on. Still no picture but the green light stayed on instead of blinking and then shutting back off.

When I measured the Vs voltage at this connector on the power supply connector, it hits 265v briefly and then drops down to 0v. Very briefly, like half a second. Similarly, the Va voltage hits 60v and then drops to 0v in the same amount of time.

[dick_barton]

Re: LG 42PC5D green light flashes three times and TV turns off.

I believe that the checks on the Zsus and Ysus are to see if there is a short circuit on one of the supplies and identify which board may be the culprit.

Z-board connector P1:
Vs <-> Gnd: 188.1kΩ
Va <-> Gnd: 25.5kΩ

The above readings appear to be fine

Y-board connector P3:
Vs <-> Gnd: ∞Ω
Va <-> Gnd: 25.5K

I'm suprised that the Yboard shows Va to Ground identical to the Zboard. Also VS ∞Ω resistance to Ground would appear to be an open circuit.

Are there fuses on the circuit boards and have you checked them all out.

[HarrySeaward]

Re: LG 42PC5D green light flashes three times and TV turns off.

Okay I may have measured wrong before.

The connector identified by the blue arrow connects the y-board to the power supply board.

The connector identified by the yellow arrow connects the y-board to the z-board.

The measurements were taken from the pins at the blue arrow, with the wires unplugged.

However when I unplug both blue and yellow connectors, I instead get:

1. Vs <-> Gnd: ∞Ω
2. Va <-> Gnd: No continuity

[HarrySeaward]

Re: LG 42PC5D green light flashes three times and TV turns off.

I've checked all the fuses I've found, all good.