Neovo F-419 no power.

[playman]

I get no power on the lcd, not even on the power led.

scematics of the PCB.


D801 was missing when I opened it, I replaced it with RGP10D instead.
D802 is PS104R D0-41 PANJIT wich seems identical to PS1010R DO-51 PANJIT wich I belive should be in D801.

Any ideas what might be wrong?

[jetadm123]

Re: Neovo F-419 no power.

Nice photos! Try checking the main fuse, F801, 3.15A for continuity. If it checks good, then check the voltage across the main cap (large green one upper right). If you are in the USA, it should measure approx. 165VDC.

[playman]

Re: Neovo F-419 no power.

Nice photos!

Thanks it took me a while though, to get them that good lol

Try checking the main fuse, F801, 3.15A for continuity. If it checks good, then check the voltage across the main cap (large green one upper right). If you are in the USA, it should measure approx. 165VDC.

I'm in Iceland, using 230v system.
The fuse was the first thing I checked
how should I check the Cap? plug the monitor in and test it or? sorry i'm still a newbie
btw I have no ESR tester.

[PlainBill]

Re: Neovo F-419 no power.

Thanks it took me a while though, to get them that good lol

I'm in Iceland, using 230v system.
The fuse was the first thing I checked
how should I check the Cap? plug the monitor in and test it or? sorry i'm still a newbie
btw I have no ESR tester.

Correct, with the monitor plugged in, CAREFULLY check the voltage across the large cap. On a 230 volt system you should see about 320 volts across the large cap.

PlainBill

[playman]

Re: Neovo F-419 no power.

Hi again, sorry for the late post.
I finally was able to check the cap, it mesured 320v

[jetadm123]

Re: Neovo F-419 no power.

Had a quick look at the schematic. Apparently, your monitor has a reset circuit, which if faulty, can cause the problems you describe.

1) look at the link below, it describes a acer monitor with the same problems you have and describes the function of the reset circuit:

https://www.badcaps.net/forum/showth...ghlight=max810

2) the chip on your board is U7, part # MCP809-300 and is located on the logic board.

3) please post a photo of the logic board.

[retiredcaps]

Re: Neovo F-419 no power.

I finally was able to check the cap, it mesured 320v

Okay, now let's check cold side for secondary DC voltages at connector P803.

Put your multimeter on 20V DC (if manual). Use a ground screw for your black probe (ground). Put your red probe on each connector pin. Report DC voltage measurement for each pin.

[playman]

Re: Neovo F-419 no power.

Had a quick look at the schematic. Apparently, your monitor has a reset circuit, which if faulty, can cause the problems you describe.

1) look at the link below, it describes a acer monitor with the same problems you have and describes the function of the reset circuit:

https://www.badcaps.net/forum/showth...ghlight=max810

2) the chip on your board is U7, part # MCP809-300 and is located on the logic board.

3) please post a photo of the logic board.

Hi jetadm123
I was not able to find the U7 chip, I must be blind
any way here are the fotos you asked for.
sorry for the flash on the picture.

[pedro]

Re: Neovo F-419 no power.

Hi jetadm123
I was not able to find the U7 chip, I must be blind

It's east-north-east from the NE corner of U6, half-way to the connector. It's in a SOT-23 style body, only three pins on this device.

[playman]

Re: Neovo F-419 no power.

Okay, now let's check cold side for secondary DC voltages at connector P803.

Put your multimeter on 20V DC (if manual). Use a ground screw for your black probe (ground). Put your red probe on each connector pin. Report DC voltage measurement for each pin.

I might have done this wrong, but this is what I did.
I had the PCB on the table(not connected to the screen), only electrical wire connected, put the black prope
into the earth wire from the socket on the PCB, wich connects to the screen metal sceleton.
Then probed the 7 wires with the red probe, and got 0 reading on all of them.
was that a right way to do it(or one of them)?

Update:
I just plugged the board into the screen, with everything connected.
and all the wires gave 0 reading.

[playman]

Re: Neovo F-419 no power.

It's east-north-east from the NE corner of U6, half-way to the connector. It's in a SOT-23 style body, only three pins on this device.

ah thanks for that, I'm getting blind apearently lol
but since the PCB did not give any volts out of it, i'm going to
wait until I can see what's going on there.

[jetadm123]

Re: Neovo F-419 no power.

ah thanks for that, I'm getting blind apearently lol
but since the PCB did not give any volts out of it, i'm going to
wait until I can see what's going on there.

Hopefully, you read the link I provided. If U7 has failed, it prevents the power supply from starting up, which results in zero ouput from the power supply.

[sabre504]

Re: Neovo F-419 no power.

U7 on pic

[retiredcaps]

Re: Neovo F-419 no power.

I might have done this wrong, but this is what I did.

Okay, let me add more detail and try again.

1) Put multimeter to 20V DC if manual.
2) Disconnect all boards. We are just going to test the power board alone. Put back all screws on the power board.
3) Put your black probe on the ground screw. Use the ground screw next to cap C848 (upper left hand corner in your picture). This will be your secondary ground.
4) Put your red probe on each pin on connector P803.
5) Report measurements for each pin.

If you still get 0V DC for all the pins, then measure the DC voltage across capacitor C810 (green small one next to the largest one). Put your black probe on the negative side of the cap and red probe on the positive side.

Report and note if the voltage is steady or fluctuating. C810 plays an important part of the startup process for the SMPS. The SMPS generates the secondary voltages that go to P803.

[PlainBill]

Re: Neovo F-419 no power.

Hopefully, you read the link I provided. If U7 has failed, it prevents the power supply from starting up, which results in zero ouput from the power supply.

Not quite correct.

U7 is the reset controller for the processor on the signal card. If it is bad the processor will not start, and the power LED will not come on. You WILL still have the normal voltages out of the power supply.

PlainBill

[jetadm123]

Re: Neovo F-419 no power.

Not quite correct.

U7 is the reset controller for the processor on the signal card. If it is bad the processor will not start, and the power LED will not come on. You WILL still have the normal voltages out of the power supply.

PlainBill

Ah, thanks PlainBill for sending me on the path to enlightenment.

[playman]

Re: Neovo F-419 no power.

Okay, let me add more detail and try again.

1) Put multimeter to 20V DC if manual.
2) Disconnect all boards. We are just going to test the power board alone. Put back all screws on the power board.
3) Put your black probe on the ground screw. Use the ground screw next to cap C848 (upper left hand corner in your picture). This will be your secondary ground.
4) Put your red probe on each pin on connector P803.
5) Report measurements for each pin.

If you still get 0V DC for all the pins, then measure the DC voltage across capacitor C810 (green small one next to the largest one). Put your black probe on the negative side of the cap and red probe on the positive side.

Report and note if the voltage is steady or fluctuating. C810 plays an important part of the startup process for the SMPS. The SMPS generates the secondary voltages that go to P803.

I still got 0 reading from the pins.
The green one is C809 and then brown circle is C810 ( I belive)
anyway I checked the C810 and got 0 reading but for a split second I got the - sign on the DMM.
Some one unknown came to me, and thought it would be funny to startle me,
while I was testing it, so I accedentily touched the big cap, wich created some sparks, but I checked it afterwards and it gave me 321volts.
So I hope I did not do any damage to it. having a double heartattack is not funn

[playman]

Re: Neovo F-419 no power.

Not quite correct.

U7 is the reset controller for the processor on the signal card. If it is bad the processor will not start, and the power LED will not come on. You WILL still have the normal voltages out of the power supply.

PlainBill

That was exactly what I thought.
Yay +1 for the newbie

[retiredcaps]

Re: Neovo F-419 no power.

The green one is C809

Sorry, check the green one. I can't see C809 from the angle of the picture.

Put your red probe on the positive leg of the small green cap C809 cap. Put your black probe on the negative leg of the small green cap.

[playman]

Re: Neovo F-419 no power.

Sorry, check the green one. I can't see C809 from the angle of the picture.

No no the fault is mine, since I took the shot slightly tilted.

Put your red probe on the positive leg of the small green cap C809 cap. Put your black probe on the negative leg of the small green cap.

I've allready done that.

anyway I checked the C810 and got 0 reading but for a split second I got the - sign on the DMM.

And if I'm not mistaken, the black part of the circle on the PCB means negative, right?