Gateway FPD1530 works for a second then dark

[freakytiki4u]

I have a Gateway FPD1530 Flat Panel LCD Monitor. When turned on it lights up and you can see the picture perfectly for about 1 second then the screen go's dark. Flashlight test reveals the picture is still there, its just dark. Power light stays solid green. Pictures of the Logic Board are attached. I cant see any bad caps or dry solder joints. Any ideas will be greatly appreciated.

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

Also, does anyone know of a device to test Capacitors in circuit?

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

I have a Gateway FPD1530 Flat Panel LCD Monitor. When turned on it lights up and you can see the picture perfectly for about 1 second then the screen go's dark. Flashlight test reveals the picture is still there, its just dark. Power light stays solid green. Pictures of the Logic Board are attached. I cant see any bad caps or dry solder joints. Any ideas will be greatly appreciated.

This is a classic description of the 'two seconds to black' symptom. I've marked up the top picture. Try measuring the AC voltage from point A to Gnd and from point B to Gnd while the backlights are on. Also check the inverter transformers for bad solder joints.

By the way, this is a picture of the inverter / power supply, not the Logic Board. (Pictures of the right board, you just gave it the wrong name.)

PlainBill

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

A gets near 10 volts AC for a split second and B gets near 6 volts AC for a split second. I have to turn the monitor on and off to make that happen while holding meter leads to proper spots. I will resolder transformer joints just to be sure. Next Sir ?

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

Resoldered joints on both small transformers, still does the same thing. Would bad caps cause this? They dont appear to be bad (not swollen).

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

Resoldered joints on both small transformers, still does the same thing. Would bad caps cause this? They dont appear to be bad (not swollen).

No, it's unlikely bad caps would cause this. You are measuring the voltage on the return line, which is proportional to the current. If you tried several times to read the voltage and got consistent results, the only conclusion I can come to is one CCFL is carrying more current than the other.

NOW, we have to figure out why. If you look at the top of the board near each of the connectors for the CCFLs you will see the transformers. If you look at the underside you will see the transformer pins are numbered 1-6 (primary side) and 7 & 8 on the secondary side. With power off, measure the resistance of each secondary.

PlainBill

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

How do I measure resistance? (I know, Im a doofus) I have a multimeter.

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

How do I measure resistance? (I know, Im a doofus) I have a multimeter.

(Well, as long as you know.) Disconnect the power supply / inverter board from the rest of the monitor turn it face down in the same position as the picture. Set the DMM to the 2K ohms range. In the lower left corner of the board you will see two points labeled 7 and 8, with the 8 above the 7. Put one probe on the pin labeled 7 and the other on the pin labeled 8. Write down the reading. Now look at the lower right corner of the board. You will see two more pins, but this time the 8 is to the left of the 7. Measure the resistance between the two points.

PlainBill

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

lol, my wife is usually first to admit Im a doofus and I runa close second.

ok, my MM only has 1K Ohm and 10 Ohm Setting so I used !k Ohm Setting.
I will post 4 pictures.
The 1st one shows my MM at rest.
The 2nd one show my MM with leads touching so you can see what it reads.
The 3rd shows the secondaries reading closest to the power plug.
The 4th shows the secondaries reading farthest away from the power plug.

I await your directions and Im sorry to be such a pain.

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

lol, my wife is usually first to admit Im a doofus and I runa close second.

ok, my MM only has 1K Ohm and 10 Ohm Setting so I used !k Ohm Setting.
I will post 4 pictures.
The 1st one shows my MM at rest.
The 2nd one show my MM with leads touching so you can see what it reads.
The 3rd shows the secondaries reading closest to the power plug.
The 4th shows the secondaries reading farthest away from the power plug.

I await your directions and Im sorry to be such a pain.

Try it again on the X10ohm scale. That should give you a reading closer to mid scale. We are looking at what might be very small differences in resistance.

PlainBill

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

ok on the 10 Ohm scale I get a consistent reading on both secondaries of 60 ohms resistance. See attached Pic of reading

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

ok on the 10 Ohm scale I get a consistent reading on both secondaries of 60 ohms resistance. See attached Pic of reading

By any chance is there enough slack in the wires so you can repeat the original test, but swapping wires to the opposite connectors?

PlainBill

[freakytiki4u]

Re: Gateway FPD1530 works for a second then dark

Do you mean test the secondaries by swapping the meter leads around? If so, Yes, and reversing the wires gives the same 60 Ohm result on each secondary.

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

Do you mean test the secondaries by swapping the meter leads around? If so, Yes, and reversing the wires gives the same 60 Ohm result on each secondary.

No, let me explain what I meant. Review posts 3 and 4. In those steps you measured the return voltages and discovered there was a difference between the two sides. The latest test indicates there is no difference between the secondaries of the two transformers. That presents a problem - ordinarily the next step would be to measure the output voltage of each transformer. However, that could easily fry your VOM (been there, done that with 5000 volts, didn't get a tee shirt, and don't want to see it done again). And we still have a problem. Is the 'B' return current lower because the 'B' transformer is not putting out high enough of a voltage, or because there is a problem with the 'B' CCFL or it's wiring OR because the 'A' CCFL is drawing too much current?

The test I am proposing is to plug the 'A' CCFL into the 'B' socket, and the 'B' CCFL into the 'A' socket. If the return voltage at the 'A' socket is still higher, that tells us the problem lies in the inverter. If the 'B' voltage is now higher, that tells us the problem lies in the CCFLs and associated wiring.

PlainBill

[elbtax]

Re: Gateway FPD1530 works for a second then dark

Just repaire an Viewsonic Optiquest Q7 displaying same problem. Removed the inverter and none of the six caps were bulging. Checked all problems PlainBill suggested above and transistors. All good. The caps were Elite so they were suspect right away. Replaced 2, 220uf-25v with Nichicon same values RZ(M) series. Replaced 2, 680uf-16v with Nichicon 1000uf, 16v.(All i had) PB(M) series. Left the high voltage cap alone and a small 50v cap.
Put back together and has been burning in with a beatiful screen since 3pm EST. So, just cause caps aren't bulging does not mean they are not bad. Hope this helps...

[mcfischer]

Re: Gateway FPD1530 works for a second then dark

I fixed many of these by replacing the 2 1Uf caps at the top edge of the board (between the bulb sockets)
Mike

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

I fixed many of these by replacing the 2 1Uf caps at the top edge of the board (between the bulb sockets)
Mike

Are you referring to the two electrolytic caps?

For what it's worth, I'm trying to put together a systematic approach to the 'Two Seconds to black' problem. That is one cause I hadn't encountered yet.

PlainBill

[mcfischer]

Re: Gateway FPD1530 works for a second then dark

Bill,
Yes the two electrolytics. I replace them with 2.2 uF just to feel better. Been doing this stuff a long time and I think it may help in the long run.
I have fixed more than 50 this past 2 years, same caps....
Mike

[rokkaholik]

Re: Gateway FPD1530 works for a second then dark

I also have this same monitor with the same problem. Which caps on which are you referring to mcfischer? Possible pics?

[PlainBill]

Re: Gateway FPD1530 works for a second then dark

I also have this same monitor with the same problem. Which caps on which are you referring to mcfischer? Possible pics?

How about this? You're the one with the monitor, you provide the picture of the inverter. If mcfischer isn't around to answer you, I'm pretty sure I can supply the identification.

PlainBill