Neovo F-419 no power.

[playman]

Re: Neovo F-419 no power.

I'm assuming that when you see "0" on your resistance readings, that means zero ohms? If yes, it means you have a short. Regardless, you should replace D801 because it's the wrong part.

I'll get to that ASAP
when I say 0 all I get on the screen is

"1    . "

Like i'm not probing anything.

Remove Q801 from the board and repeat test to verify your initial readings.

I did the same testing as earlyer and have the same readings.

black on pin 2 red on pin 3 gave me some 20-60 for a split second. (changes every time I check it)(made a tipo in earlyer thread, black was on pin 2 not 1)
I tested like this,
Black pin1 Red pin 2 and 3
Black pin2 Red pin 3

R800 seems a bit high, but other parts could be affecting your reading. Remove it from the board and repeat test.

It mesures about 5 then rapidly drops to 1.1 but after few secs it then drops to 1.0


PS.
My DMM is a cheap one.
when put on 200ohm setting I get 0.8 ohms when shorting pins.

[jetadm123]

Re: Neovo F-419 no power.

I'm assuming that when you see "0" on your resistance readings, that means zero ohms? If yes, it means you have a short. Regardless, you should replace D801 because it's the wrong part.

Remove Q801 from the board and repeat test to verify your initial readings.

R800 seems a bit high, but other parts could be affecting your reading. Remove it from the board and repeat test.

[playman]

Re: Neovo F-419 no power.

C809 is the 10uf 25V startup cap, which read 0 volts when you measured across it. Correct?

Actually it's 10uf 100V, but yes it measured 0v

With power off do the following:

1) check the fusible resistor, R800, .2ohms 1W, to see if it's open.

2) check R807, D802 and Q801 for shorts.

R800= 1.1 @ 200ohm on DMM
R807= 15.6 @ 200ohm on DMM
D801= 78.1 @ 200ohm on DMM it reads 78 for a split second then 0
D802= 17.6 @ 200ohm on DMM

Q801= 0
black on pin 1 red on pin 3 gave me some 70 for a split second.
I tested like this,
Black pin1 Red pin 2 and 3
Black pin2 Red pin 3

Additional info: you mentioned that you replaced D801,PS1010R, with a RGP10D. The PS1010R is rated 1000V@1A. The RGP10 is rated 200V@1A. Add checking D801 for a short to your list.

I think it's broken, but I was so sure that I had equalent replacement part.
Oh well, that teaches me to pay more attention.

[jetadm123]

Re: Neovo F-419 no power.

Additional info: you mentioned that you replaced D801,PS1010R, with a RGP10D. The PS1010R is rated 1000V@1A. The RGP10 is rated 200V@1A. Add checking D801 for a short to your list.

[jetadm123]

Re: Neovo F-419 no power.

C809 is the 10uf 25V startup cap, which read 0 volts when you measured across it. Correct?

With power off do the following:

1) check the fusible resistor, R800, .2ohms 1W, to see if it's open.

2) check R807, D802 and Q801 for shorts.

[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?

[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.

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

[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

[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.

[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

[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.

[sabre504]

Re: Neovo F-419 no power.

U7 on pic

[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.

[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.

[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.

[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.

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.

[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.

[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.