LG Flatron L1750S - Stopped to work

[rf.pereira]

Re: LG Flatron L1750S - Stopped to work

Thanks piernov and Th3_uN1Qu3!

Sorry but I'm sure about the pin number, so I'll upload a picture of Q502 with what I think are the pin's numbers.
Based on my picture:

pins 1 and 3: 4.29V
pins 1 and 2: 5.01V
pins 3 and 2: 0.72V
pin 1 and GND: 5.01V
pin 3 and GND: 0.72V

0.74V between 3rd pin and ground then? Q502 could be bad. Try to remove Q502 and put a capacitor between base of Q503 (pin 1) and ground, 33uF/6.3V at least I would say, then check if the monitor turns on.

Did you mean base of Q502 (pin 1)? And ground = pin 2?
I have a 33uF/25V, is that ok?

Do you get a green light when you push the power button or do you get nothing?

Nothing happens...

[piernov]

Re: LG Flatron L1750S - Stopped to work

Did you mean base of Q502 (pin 1)? And ground = pin 2?

Yes, with the positive side of the capacitor on pin 1 and the negative side on pin 2.

I have a 33uF/25V, is that ok?

Yep should be fine.

[rf.pereira]

Re: LG Flatron L1750S - Stopped to work

Nothing happened...
5.03V passing through the capacitor and even pressing the power button nothing happened.

[piernov]

Re: LG Flatron L1750S - Stopped to work

So you removed Q502 and you still have 5V on U501's RST pin? You could try to disconnect R535, but I'm not sure the µC will start reliably.

[rf.pereira]

Re: LG Flatron L1750S - Stopped to work

So you removed Q502 and you still have 5V on U501's RST pin? You could try to disconnect R535, but I'm not sure the µC will start reliably.

No, on U501's RST pin (7) I have 0V and 5V on pin 8.
Maybe I made a mistake in the first time you asked me the U501's values... sorry about that.
I'll upload the U501's datasheet.

[piernov]

Re: LG Flatron L1750S - Stopped to work

No idea then, maybe there is an issue with U501 (dead or corrupt firmware for example)…