emachines e19t6w inverter powersupply help

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

Okay, I did the measurements and the rectifier is good, and the voltage is like you said, 1.4 from the input.

Also, I checked the voltage VCC5V / VCC5V / GND / GND and there's no voltage there. (on the cable that connects to the video board)

Okay, so we know we have main power and no secondary voltage. The 5V is what powers the logic board to turn on the monitor.

Test the FET on the heatsink for shorts (ohms, power off). The FET is above the big cap. It is marked S G D.
Any reading under 100 ohms is suspicious.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

Okay, so we know we have main power and no secondary voltage. The 5V is what powers the logic board to turn on the monitor.

Test the FET on the heatsink for shorts (ohms, power off). The FET is above the big cap. It is marked S G D.
Any reading under 100 ohms is suspicious.

Done,
with multimeter at 2k scale, no short at all.
at 20k I have some values but are very high (normal)

Good way of troubleshooting!

Tks! let's keep moving forward.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

On the back side of the board, there is a chip right next to the connectors (right below the connector - upper right hand corner on the backside photo). I can't make out the designation, but it looks like a 5 legged chip.

What is the part number or writing on that chip?

BTW, can you get a focused picture of the backside? Take the board on a sunny day (which shouldn't be hard in Brazil), put your camera on macro mode and flash off.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

Done,
with multimeter at 2k scale, no short at all.
at 20k I have some values but are very high (normal)

It is close to midnight and I'm off to bed. We can continue this tomorrow.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

It is close to midnight and I'm off to bed. We can continue this tomorrow.

NCP1337
It's a 7 pin IC

I have replaced it, because it was cracked (very easy to identify).

I will post the pictures. I got those.

Yeap, here is almost 3am.

tks for your help.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

NCP1337
It's a 7 pin IC

I have replaced it, because it was cracked (very easy to identify).

1) The datasheet for NCP1337 is at

http://pdf1.alldatasheet.com/datashe...NCP1337PG.html

You will need to download that and refer to it for voltage measurements. Pin 4 is your ground. Please list voltages for all pins.

2) Did you replace NCP1337 before you posted here or after? It matters to know when you replaced it.

3) Was the original IC that was cracked also a NCP1337?

4) What is the value of the capacitor just above the transformer (SPW-055 Rohs)? Who makes it?

5) There is a yellow "jeanbean" fuse next to the 79070140 number. Please measure that fuse and make sure it is 0.3 ohms.

6) If possible, can you check for 5V DC with the logic card disconnected from the power/inverter board? I have one LCD where the 5V DC and 19V DC secondary voltages are stable and present ONLY IF the logic card is disconnected (implying a short somewhere).

[jselvatici]

Re: emachines e19t6w inverter powersupply help

1) The datasheet for NCP1337 is at

http://pdf1.alldatasheet.com/datashe...NCP1337PG.html


You will need to download that and refer to it for voltage measurements. Pin 4 is your ground. Please list voltages for all pins.


2) Did you replace NCP1337 before you posted here or after? It matters to know when you replaced it.

3) Was the original IC that was cracked also a NCP1337?

4) What is the value of the capacitor just above the transformer (SPW-055 Rohs)? Who makes it?

5) There is a yellow "jeanbean" fuse next to the 79070140 number. Please measure that fuse and make sure it is 0.3 ohms.

6) If possible, can you check for 5V DC with the logic card disconnected from the power/inverter board? I have one LCD where the 5V DC and 19V DC secondary voltages are stable and present ONLY IF the logic card is disconnected (implying a short somewhere).

1) The datasheet for NCP1337 is at
You will need to download that and refer to it for voltage measurements. Pin 4 is your ground. Please list voltages for all pins.
-> Taking the Pin 4 as ground, the voltage is Pin 1= 0VDC Pin 2= 0VDC Pin 3= 0VDC Pin 5= 11VDC Pin 6= 0VDC and Pin 8= 275VDC

2) Did you replace NCP1337 before you posted here or after? It matters to know when you replaced it.
-> I replace it after the problem. The only thing is, the previous component was SMD and I couldn't found SMD, so I installed a normal one.

3) Was the original IC that was cracked also a NCP1337?
-> Yeap, part of it was off.

4) What is the value of the capacitor just above the transformer (SPW-055 Rohs)? Who makes it?
-> The blue one says "JN222M 440~X1250 400~Y 17DC
-> The "electrolitic" says 47uF 25v.

5) There is a yellow "jeanbean" fuse next to the 79070140 number. Please measure that fuse and make sure it is 0.3 ohms.
-> It has 0.3 ohms.


6) If possible, can you check for 5V DC with the logic card disconnected from the power/inverter board? I have one LCD where the 5V DC and 19V DC secondary voltages are stable and present ONLY IF the logic card is disconnected (implying a short somewhere).
-> I did this measure before and there's no 5V there.

Now I have another problem. During the measurements one resistor blows out. And this was replaced before because it was open, so something is in short and is blowing the resistor. It's the last picture.
After it blows, I turn off the power. Should I power on again?

It's getting very intersting this Troubleshoot.

Tks!

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

Now I have another problem. During the measurements one resistor blows out. And this was replaced before because it was open, so something is in short and is blowing the resistor. It's the last picture.
After it blows, I turn off the power. Should I power on again?

1) Okay, please disclose everything else that you found BEFORE you posted. Letting us know about the bad NCP and open resistor is something we need to know. Was anything else replaced or found wrong?

2) I'm assuming you are talking about the big red resistor just above the main filter cap that is blown/open?

3) Still waiting for clear focused pictures (especially the backside). You will have to trace the big red resistor pins on the back side to see where they connect to. If they connect to a diode or FET or transistor, test those in circuit for shorts. For diodes, use the diode test on your multimeter.

Here is an example of someone (without schematics) can trace out a circuit.

https://www.badcaps.net/forum/attach...6&d=1281189035

Notice how clear and focused his photo is.

4) Do not power on anymore until we find the cause of the resistor going open.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

1) Okay, please disclose everything else that you found BEFORE you posted. Letting us know about the bad NCP and open resistor is something we need to know. Was anything else replaced or found wrong?

2) I'm assuming you are talking about the big red resistor just above the main filter cap that is blown/open?

3) Still waiting for clear focused pictures (especially the backside). You will have to trace the big red resistor pins on the back side to see where they connect to. If they connect to a diode or FET or transistor, test those in circuit for shorts. For diodes, use the diode test on your multimeter.

Here is an example of someone (without schematics) can trace out a circuit.

https://www.badcaps.net/forum/attach...6&d=1281189035

Notice how clear and focused his photo is.

4) Do not power on anymore until we find the cause of the resistor going open.

Okay,
I'm going to work now, and as soon I'm back home, I can do those actions.

Please wait few hours.

Tks!

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

6) If possible, can you check for 5V DC with the logic card disconnected from the power/inverter board? I have one LCD where the 5V DC and 19V DC secondary voltages are stable and present ONLY IF the logic card is disconnected (implying a short somewhere).
-> I did this measure before and there's no 5V there.

Was that 5V DC measurement with or without the logic board connected though?

[jselvatici]

Re: emachines e19t6w inverter powersupply help

Was that 5V DC measurement with or without the logic board connected though?

Without the logic board connected.

tks!

[jselvatici]

Re: emachines e19t6w inverter powersupply help

Hi, I'm back... I could not wait until get home to still working on this, let move...

1) Okay, please disclose everything else that you found BEFORE you posted. Letting us know about the bad NCP and open resistor is something we need to know. Was anything else replaced or found wrong?
-> yes, since the problem begins, I replaced the NCP1337, the resistor (R805)(looks like a fuse-resistor), the FET that is marked with S G D, and 2 SMD's resistor (R807) and (R831).

2) I'm assuming you are talking about the big red resistor just above the main filter cap that is blown/open?
-> Exactly! The original one was a very low resistance, I don't remember now the value. Also, the FET that I installed now is an alternative of the original. (I don't remember the FET code now).

3) Still waiting for clear focused pictures (especially the backside). You will have to trace the big red resistor pins on the back side to see where they connect to. If they connect to a diode or FET or transistor, test those in circuit for shorts. For diodes, use the diode test on your multimeter.
-> well, now I have my FET all shorted. The resistor that you talk about goes from the negative right after the rectifier to the "S" of the FET.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

-> well, now I have my FET all shorted. The resistor that you talk about goes from the negative right after the rectifier to the "S" of the FET.

I think we should start from square 1 since we have a number of things possibly bad.

1) I would start at D801 and test it in circuit with ohms to make sure there are no shorts since D801 feeds right into R805.

2) Test R805 out of circuit to ensure it meets the proper ohms value to the color code.

3) Retest NCP 1337 for short.

4) Test D802 diode.

5) Test R804 out of circuit ensure it meets the proper ohms value to the color code.

6) Test the SMD resistors in circuit to make sure they match their markings.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

Forgot to add test D804.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

I think we should start from square 1 since we have a number of things possibly bad.

1) I would start at D801 and test it in circuit with ohms to make sure there are no shorts since D801 feeds right into R805.

2) Test R805 out of circuit to ensure it meets the proper ohms value to the color code.

3) Retest NCP 1337 for short.

4) Test D802 diode.

5) Test R804 out of circuit ensure it meets the proper ohms value to the color code.

6) Test the SMD resistors in circuit to make sure they match their markings.

Here is:

1) I would start at D801 and test it in circuit with ohms to make sure there are no shorts since D801 feeds right into R805.
-> D801 (the rectifier) is okay, it only goes in the direction to convert AC to DC and the values are 631ohms.

2) Test R805 out of circuit to ensure it meets the proper ohms value to the color code.
-> I dont know if I can trust on reading because part of it came off, so it reads 1k5ohms. Picture available


3) Retest NCP 1337 for short.
-> testing the NCP1337, using Pin 4 as a reference I got to Pin1= open Pin2= open Pin3= 2kohms Pin5= 2ohms Pin6= 205ohms Pin8= open

4) Test D802 diode.
-> D802 is okay about 600ohms in the diode multimeter scale.

5) Test R804 out of circuit ensure it meets the proper ohms value to the color code.
-> 67kohms (by color is 68k)


6) Test the SMD resistors in circuit to make sure they match their markings.
-> The SMF's are okay, they match.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

This is the FET that I changed because it was all shorted.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

2) Test R805 out of circuit to ensure it meets the proper ohms value to the color code.
-> I dont know if I can trust on reading because part of it came off, so it reads 1k5ohms. Picture available

Yes, that resistor looks dodgy. I would probably replace it.

3) Retest NCP 1337 for short.
-> testing the NCP1337, using Pin 4 as a reference I got to Pin1= open Pin2= open Pin3= 2kohms Pin5= 2ohms Pin6= 205ohms Pin8= open

Sorry, I made a mistake here. I don't see anyway to properly test this PWM. I'm helping 5 or 6 people at once and I got confused with another thread. Too much sun yesterday!

Let's assume the PWM is okay for now.

The good thing about your board is that there are very few components on the top side. If you can test every component in that section, it shouldn't take more than 10 or 15 minutes to measure the diodes, resistors, and FETs.

One other thing to do is to "backtrace" the two 5V rails to see what the path looks like. That way, you know what to measure for secondary voltages.

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

-> The "electrolitic" says 47uF 25v.

Sorry, I forgot to write this yesterday.

If you haven't replaced this cap, please do so with a low ESR one like Panasonic FM or Rubycon MCZ series.

This cap might be used to help the SMPS power supply start up to provide 5V DC.

[jselvatici]

Re: emachines e19t6w inverter powersupply help

Yes, that resistor looks dodgy. I would probably replace it.



Sorry, I made a mistake here. I don't see anyway to properly test this PWM. I'm helping 5 or 6 people at once and I got confused with another thread. Too much sun yesterday!

Let's assume the PWM is okay for now.

The good thing about your board is that there are very few components on the top side. If you can test every component in that section, it shouldn't take more than 10 or 15 minutes to measure the diodes, resistors, and FETs.

One other thing to do is to "backtrace" the two 5V rails to see what the path looks like. That way, you know what to measure for secondary voltages.

I measured some components and looks good, the only thing now is the Main fuse is open, I have to wait to buy one like that... may be tomorrow I can power up the board again. (I already replace the resistor and the FET)

Tks!

[retiredcaps]

Re: emachines e19t6w inverter powersupply help

I have to wait to buy one like that.

IF the parts are inexpensive, maybe get 2 fuses? At some point, this board may be unrepairable if it was damaged by the storm (power surge?). There may be PCB or internal board damage that is not fixable.

PS. Don't forget about the 47uF cap.