Gateway FPD1976w / LE1936 Problem

[bigtex2712]

Re: Gateway FPD1976w / LE1936 Problem

So you figure if I just replace that one the problem will be solved?

[retiredcaps]

Re: Gateway FPD1976w / LE1936 Problem

So you figure if I just replace that one the problem will be solved?

The logic board requires 5V DC. It then uses the voltage regulators to convert that to other voltages (like 1.8, 2.5, 3.3V DC) to feed the other components. So if 3.3V is required and the components are only getting 1.42V, then quite a bit of the circuitry is not going to come on and work at all.

These voltage regulators are called jelly bean parts because they are found everyone and made by a lot of people. If you have junk boards, you may be able to reuse an old one as a test (assuming the used one is good).

[bigtex2712]

Re: Gateway FPD1976w / LE1936 Problem

Actually, I just came across something. I went to go retest the AS1117L-33 prong 2 and initial when I plugged power into it, the reading was a 3.2V but after about 2 minutes it dropped down to 1.4V again. I would have to assume that this definitely means the component is bad.

[retiredcaps]

Re: Gateway FPD1976w / LE1936 Problem

Actually, I just came across something. I went to go retest the AS1117L-33 prong 2 and initial when I plugged power into it, the reading was a 3.2V but after about 2 minutes it dropped down to 1.4V again. I would have to assume that this definitely means the component is bad.

Voltage regulators are spec'd to +/- 1%. So

3.3 x 1.01 = 3.333
3.3 x 0.99 = 3.267

This is why it is so important to have an accurate multimeter with fresh batteries (as previous posts).

So if 3.2 means 3.20V, that is still out spec.

[bigtex2712]

Re: Gateway FPD1976w / LE1936 Problem

Well yes I understand that, but the thing is the voltage drops after about 2 minutes from that normal output down to 1.42V.

[cadillacman]

Re: Gateway FPD1976w / LE1936 Problem

I just got one of these. Plugged in, blue power lamp just flashes. press power, still just flashes, with an input still jut flashes the lght.

THese have some " su'scon" caps (haha) and i have two obiously bad ones. c509 is a 220uf/35v that is bulged, and c818 is a 1000uf/10v that is bulged. I believe i will recap this and post the results.

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

I found one of these monitors in the recycle box plugged it in and nothing. No LED or picture. I opened it up and found two bulged caps. Replaced all caps & put the boards back on the display and hooked up both power and VGA.

Gateway splash screen shows up followed by a bar with red green and blue sections. Then the monitor goes blank. The blue LED lights up and stays solid until the screen blanks at which time the LED turns orange. The on/off button will turn the monitor off and on and I get a repeat of the description above.

Before putting the power board back together with the video board and screen I checked the two fuses which were good and the voltage on the large cap (173v) and the bridge rectifier also (173vac) I tried checking voltage at the connector between the PB and Video board. I could not get a reading on the two 5v pin or on/off pin or the other pin (brightness) (6 total) last one is ground all read in the mv range and those readings were bouncing around.

Any ideas on what I should look for next?

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

I took the LCD screen off and plugged in the power board and video board to AC. The connector between the two boards now reads:
VCC5v = 5.13v
VCC5v = 5.13v
Grnd
Brightness = 3.29v
On/Off = 3.23v when on
Grnd.

On video board Voltage Regulators
U103
AS1117L-33
Leg 1 = 0.0v
Leg 2 = 3.3v
Leg 3 = 5.13v

U104
AS1117L-18
Leg 1 = 0.0v
Leg 2 = 1.80v
Leg 3 = 5.13v

U103/104 appear to be ok, is that right?

Any ideas as to what to look for next?

[budm]

Re: Gateway FPD1976w / LE1936 Problem

OK, the inverter backlights circuit since it is getting the correct voltages for BL_ON and the Dimming from the logic board so the backlights should stay on.
The inverter transformer has 2 pins on the output side, what resistance do get at those 2 pins (use 2K Ohm scale)?

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

OK, the inverter backlights circuit since it is getting the correct voltages for BL_ON and the Dimming from the logic board so the backlights should stay on.
The inverter transformer has 2 pins on the output side, what resistance do get at those 2 pins (use 2K Ohm scale)?

T501
Pin 7&8
0.605

T502
Pin 7&8
0.607

My DMM is Auto Ranging

[budm]

Re: Gateway FPD1976w / LE1936 Problem

OK, they are fine, so need to look at the drive circuits next.
What DC voltage do you have at the two legs of C817?

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

OK, they are fine, so need to look at the drive circuits next.
What DC voltage do you have at the two legs of C817?

The reading was 14.79 vdc.

[budm]

Re: Gateway FPD1976w / LE1936 Problem

OK, you are getting B+ to the inverter section, next we need to look further in the inverter section, I will need to trace out the connections on the bottom side of the board.
BTW, can you read the P/N on those two 8-PIN MOSFET's, we will need to check the Source and Drain resistance.

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

OK, you are getting B+ to the inverter section, next we need to look further in the inverter section, I will need to trace out the connections on the bottom side of the board.
BTW, can you read the P/N on those two 8-PIN MOSFET's, we will need to check the Source and Drain resistance.

Ok I will get them to you tomorrow.

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

OK, you are getting B+ to the inverter section, next we need to look further in the inverter section, I will need to trace out the connections on the bottom side of the board.
BTW, can you read the P/N on those two 8-PIN MOSFET's, we will need to check the Source and Drain resistance.

This is the link to the datasheet on the Mosfets: http://pdf1.alldatasheet.com/datashe.../AP9971GD.html

Which pins do you want me to check for resistance?

[Davi.p]

Re: Gateway FPD1976w / LE1936 Problem

Budm you are trying to troubleshoot a 2 sec. to black problem but he said "Gateway splash screen shows up followed by a bar with red green and blue sections", i don't think this behavior is normal, Killian: can you watch in a dark room with a torch pointed at the screen and mon. switched on and hooked to a running pc if you see a dark picture? Use black and white pic or high contrast.

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

Budm you are trying to troubleshoot a 2 sec. to black problem but he said "Gateway splash screen shows up followed by a bar with red green and blue sections", i don't think this behavior is normal, Killian: can you watch in a dark room with a torch pointed at the screen and mon. switched on and hooked to a running pc if you see a dark picture? Use black and white pic or high contrast.

Currently I have it apart testing components for Bud. I will put it all back together and check to see if I have anything on the display screen.

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

OK, you are getting B+ to the inverter section, next we need to look further in the inverter section, I will need to trace out the connections on the bottom side of the board.
BTW, can you read the P/N on those two 8-PIN MOSFET's, we will need to check the Source and Drain resistance.

Bud,
I took a resistance reading On U501 S1-D1 = 1.80 Kohms
On U502 same pins = 7.95 Kohms

Do want any other pins checked?

[budm]

Re: Gateway FPD1976w / LE1936 Problem

"Gateway splash screen shows up followed by a bar with red green and blue sections. Then the monitor goes blank" The word BLANK means black screen with no backligts or backlights on but no image on the screen, it sounds to me the backlights go out.
"The blue LED lights up and stays solid until the screen blanks at which time the LED turns orange" This one sounds like the monitor goes into standby made due to lack of signals from running PC. Please clarify.
The MOSFET's readings, since they are dual MOSFET's what are the readings of S2-D2?

[killian6pk]

Re: Gateway FPD1976w / LE1936 Problem

"Gateway splash screen shows up followed by a bar with red green and blue sections. Then the monitor goes blank" The word BLANK means black screen with no backligts or backlights on but no image on the screen, it sounds to me the backlights go out.
"The blue LED lights up and stays solid until the screen blanks at which time the LED turns orange" This one sounds like the monitor goes into standby made due to lack of signals from running PC. Please clarify.
The MOSFET's readings, since they are dual MOSFET's what are the readings of S2-D2?

U501 Pin S2 - D2 = 7.92 Kohms
U502 Pin S2 - D2 = 7.89 Kohms

Bud,
What I said in Post #47 is what is happening. I have not checked yet for video without backlights, because I have had the boards seperated to check for what you wanted.
EDIT: Bud I realize now that what you are saying is that I have described two seperate problems. As I said above I did not check for a picture without backlights, but I will put the boards and screen back together and check to see if I have a picture.