Dell e171fpb monitor no power or LED lights

[miamiflorida]

Hello Guys,

My Dell e171fpb after a brief power outage won't power up at all, none of the LED lights on the front will lid, power button will not turn it on at all.

I have opened the monitor, it looks like all of the A/C section of the PSU is fine, checked all the capacitors and they seems to be OK, no visible crack, burns or anything obvious.

Now i can't get any voltage out on either of the two connectors going out of the power supply board.

See the attached pictures.

Please any help is greatly appreciated, Thank you...

[retiredcaps]

Originally Posted by miamiflorida

My Dell e171fpb after a brief power outage won't power up at all, none of the LED lights on the front will lid, power button will not turn it on at all.

See the attached pictures.

Things to check with there is no power or power LED.

With power off and LCD unplugged.

1) Fuse. A good fuse should be 0.3 ohms.
2) Bridge rectifier. You can measure this in circuit to see if it is shorted. Number your pins 1 to 4 and measure the resistance between 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4.

If these two test are okay, we can give more suggestions.

PS. Your pictures are a bit small and we can't make out all the details. You can post up to 2000x2000 resolution.

[miamiflorida]

Thank you,

There's only one fuse, and is good, I've read 125v, 0.3ohms across it as you stated.

I' ll check the "rectifier"

The pictures... (sight) that's almost the best I can get out this cheap camera.

Thank you again...

[miamiflorida]

Sorry about the double post above, anyways...

I'm getting O.L while reading between all 4 pins of "BD601" which I assume is the Bridge R.

FYI there's a 100uf capacitor right behind it and it is putting out 165vdc.

[PlainBill]

Originally Posted by miamiflorida

Sorry about the double post above, anyways...

I'm getting O.L while reading between all 4 pins of "BD601" which I assume is the Bridge R.

FYI there's a 100uf capacitor right behind it and it is putting out 165vdc.

You've made the most important test right there. If you've got 165 volts across the big cap the input fuse and bridge rectifier are good. By the way, be very careful around that cap. It will hold that charge for quite a while. While it probably won't be lethal, 165 volts can give you an attitude change.

Now you also indicted there was no power out of the output connectors. The logical place to look is the smps controller. It is the 8 pin IC in the lower right corner of the last picture. What is the part number?

I understand about cheap cameras. However, the help process is a lot like GIGO in computer programming. The better the information you give us, the better the help we can give you. At a very minimum retake the last picture in natural light without a flash. Glare is a killer - it always seems to be over the the area I am most interested in.

PlainBill

[retiredcaps]

Originally Posted by PlainBill

You've made the most important test right there. If you've got 165 volts across the big cap the input fuse and bridge rectifier are good. By the way, be very careful around that cap. It will hold that charge for quite a while. While it probably won't be lethal, 165 volts can give you an attitude change.

Testing across the big cap for voltage would have been my next suggestion, but I'm personally hestiant writing instructions when I'm tired near midnight.

Especially instructions that involve mains line voltage. And while the OP probably lives in Miami, Florida as the screen name suggests, I would hate to see anyone experince 240V * 1.4 if they should be from Europe.

[miamiflorida]

Originally Posted by PlainBill

You've made the most important test right there. If you've got 165 volts across the big cap the input fuse and bridge rectifier are good. By the way, be very careful around that cap. It will hold that charge for quite a while. While it probably won't be lethal, 165 volts can give you an attitude change.

Now you also indicted there was no power out of the output connectors. The logical place to look is the smps controller. It is the 8 pin IC in the lower right corner of the last picture. What is the part number?

I understand about cheap cameras. However, the help process is a lot like GIGO in computer programming. The better the information you give us, the better the help we can give you. At a very minimum retake the last picture in natural light without a flash. Glare is a killer - it always seems to be over the the area I am most interested in.

PlainBill

I tried, but unfortunately this camera above 640x480 becomes blurred.

This board is made by BENQ and the part number is; BENQ ETL-XPC-801.

How should I test the SMPS CONTROLLER as you suggested, that one is labeled IC601.

I thank you both for your patience and help

Don't worry about me getting shocked, I am an industrial electrician by trade and I have had received several.

[retiredcaps]

Originally Posted by miamiflorida

How should I test the SMPS CONTROLLER as you suggested, that one is labeled IC601.

IC601 is the PCB designation. PlainBill wants you to read the part number off that chip. There is no way we can read that number from those pics.

To get the best pictures, put your camera on macro mode and take the picture next to a window on a sunny day.

[miamiflorida]

OK, don't know if this is of any help, but I checked for voltage across the IC601 and I'm getting 13.7vdc between pin-6 and all the other pins.

Just so you know I also check voltage on the Transformer (T601) and I'm reading 165vdc on all 4 pins on the bottom side and nothing on the upper side.

If you are able... see picture.

[miamiflorida]

Originally Posted by retiredcaps

IC601 is the PCB designation. PlainBill wants you to read the part number off that chip. There is no way we can read that number from those pics.

To get the best pictures, put your camera on macro mode and take the picture next to a window on a sunny day.

Oh ok, this what's printed on it;

CHIN
UC38428
K45323

[retiredcaps]

Originally Posted by miamiflorida

OK, don't know if this is of any help, but I checked for voltage across the IC601 and I'm getting 13.7vdc between pin-6 and all the other pins.

Just so you know I also check voltage on the Transformer (T601) and I'm reading 165vdc on all 4 pins on the bottom side and nothing on the upper side.

The datasheet for your SMPS is at

http://pdf1.alldatasheet.com/datashe...LD/UC3842.html

Just out of curiousity, is this a 1M or 2M camera phone?

edit: I'm not 100% sure here, but do you have a transformer ring tester?

[miamiflorida]

Originally Posted by retiredcaps

The datasheet for your SMPS is at

http://pdf1.alldatasheet.com/datashe...LD/UC3842.html

Just out of curiousity, is this a 1M or 2M camera phone?

edit: I'm not 100% sure here, but do you have a transformer ring tester?

No, is a little digital Canon 7m camera, but the zoom is only 4x.

[PlainBill]

Originally Posted by retiredcaps

Testing across the big cap for voltage would have been my next suggestion, but I'm personally hestiant writing instructions when I'm tired near midnight.

Especially instructions that involve mains line voltage. And while the OP probably lives in Miami, Florida as the screen name suggests, I would hate to see anyone experince 240V * 1.4 if they should be from Europe.

I'm more pragmatic. "Consider it evolution in action" 'Oath of Fealty' by Larry Niven and Jerry Pournelle.

PlainBill

[PlainBill]

Originally Posted by miamiflorida

No, is a little digital Canon 7m camera, but the zoom is only 4x.

Pin 5 on the UC3842 is ground. Pin 7 is Vcc. What is the voltage from pin 5 to pin 7?

PlainBill

[retiredcaps]

Originally Posted by miamiflorida

No, is a little digital Canon 7m camera, but the zoom is only 4x.

Wow, for a Canon, I expect much more unless it is physically damaged.

Humor me. Try this for future pictures. Set the Canon to its highest picture resolution. Put it on macro mode (usually a flower icon). Turn off flash. Turn off zoom (optical and digital).

Take the board next to the window on a sunny day. Press and hold the shutter halfway. It should tell you on the LCD what the shutter speed is. On a very good day, I can get 1/500 which produce crisp sharp pictures.

Anything above 1/125 should produce quality pics.

edit: The last pic of the backside with the yellow outline box is pretty good, but the resolution is low and it is hard to see all the lettering.

[miamiflorida]

Originally Posted by PlainBill

Pin 5 on the UC3842 is ground. Pin 7 is Vcc. What is the voltage from pin 5 to pin 7?

PlainBill

13.7vdc

[retiredcaps]

Originally Posted by PlainBill

"Consider it evolution in action" 'Oath of Fealty' by Larry Niven and Jerry Pournelle.

Jerry Pournelle. Wow, that is a name I haven't heard in probably 15+ years. I remember eagerly going to the library everyday looking for the latest issue of Byte magazine to read his column.

[miamiflorida]

You think the IC is bad ?

[PlainBill]

Originally Posted by miamiflorida

You think the IC is bad ?

Probably not. But 13.7 volts is below the startup voltage, but above the shutdown voltage. This MIGHT be due to a bad cap, resistor that has changed it's value, or the IC is working. With power on, CAREFULLY measure the voltage on the rest of the pins, using pin 5 as ground.

PlainBill

[miamiflorida]

Originally Posted by PlainBill

Probably not. But 13.7 volts is below the startup voltage, but above the shutdown voltage. This MIGHT be due to a bad cap, resistor that has changed it's value, or the IC is working. With power on, CAREFULLY measure the voltage on the rest of the pins, using pin 5 as ground.

PlainBill

Well, none of the others pins puts out anything.