Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Do you mean ground screw on the metal base of the monitor (kind of AC ground, yellow-green wire) or ground of each voltage regulator?

Example of ground screw on each board circled in light blue.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

The voltage regulators (in yellow) will have to be tested to see if they output the correct voltage. Even though they are not shorted (which is good), they need to output the correct voltage.

With power on and lcd plugged in, use a ground screw for your black proble. Put your multimeter on 20V DC. Then put your red probe on each pin of the voltage regulator. Report all voltages.

Do you mean ground screw on the metal base of the monitor (kind of AC ground, yellow-green wire) or ground of each voltage regulator?

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Also, why two different meters shows different numbers?

For diode testing, some multimeters use OL or "1" to indicate out of range. As long as the diode doesn't show the same reading in both directions, it is likely to be good.

On this board, the diodes could be in "parallel" so the multimeter diode test threshold may not be enough to trigger the "0L" on the Meterman.

I had a Meterman 15XP, but I gave it away to a relative for business use so I'm familiar with the Meterman brand. I have used an autoranging Canadian Tire multimeter.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

4. If J033 is voltage regulator then it's OK, no short.
5. If J023 and J032 are voltage regulators then they are good, no shorts.

The voltage regulators (in yellow) will have to be tested to see if they output the correct voltage. Even though they are not shorted (which is good), they need to output the correct voltage.

With power on and lcd plugged in, use a ground screw for your black proble. Put your multimeter on 20V DC. Then put your red probe on each pin of the voltage regulator. Report all voltages.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Diode | Meterman read1 | Meterman read2 | Mastecraft read1 | Mastercraft read2
FD7/8 |   0.141V  |   0.737V*  |    122    |   1085*

* means that with red lead to cathode it shows 1085, than I removed one lead and put it back and the next reading is 1020. Remove a lead and put it back - it shows 780..800. That's weird.

FD7/8 could be bad. Let's note that they could be bad and leave the soldered in for now. You may have to desolder them and test them out of circuit to verify at a later point.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

4. If J033 is voltage regulator then it's OK, no short.
5. If J023 and J032 are voltage regulators then they are good, no shorts.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

OK, here are some results about question 3.

I used 2 multimeters: my personal Mastercraft 52-0060-2 (cheap one, from Canadian Tire for 20$ bundled) and the office one Meterman 37XR.
Mastercraft does not show eng units during diode test and the scale is weird. Anyway, here are the results:

Diode | Meterman read1 | Meterman read2 | Mastecraft read1 | Mastercraft read2
FD1/2 |   0.145V  |   1.329V  |    122    |   Overrange
FD3/4 |   0.143V  |   1.256V  |    120    |   Overrange
FD5/6 |   0.142V  |   1.543V  |    119    |   Overrange
FD7/8 |   0.141V  |   0.737V*  |    122    |   1085*

* means that with red lead to cathode it shows 1085, than I removed one lead and put it back and the next reading is 1020. Remove a lead and put it back - it shows 780..800. That's weird.

4. 4 transistors J598 are good, no shorts between 1-2-3.
6. 5 fuses on USB board are good (F1-F4, F19).

Where are voltage regulators on 4. and 5.?
Any ideas? Also, why two different meters shows different numbers?
I will post next readings soon.
Thanks

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Here (http://www.elexp.com/t_test.htm) it's said that to test "in circuit" I will need to unsolder one end.

Thanks.

No you don't have to unsolder anything. Measure everything as is first. If the readings are suspicious, then unsolder one leg.

Yes, all those circled are diodes. To test a diode in circuit,

a) put your multimeter in diode test mode
b) put your black lead on one side and the red lead on the other - record reading
c) reverse the leads - recording reading

A good diode should read 0.3V to 0.7V in one direction and 0L in the other. If you get a reading in both directions, you will have to desolder one leg and retest to verify.

Report all your measurements.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Hi Retired,

Here (http://www.elexp.com/t_test.htm) it's said that to test "in circuit" I will need to unsolder one end. I will try tomorrow again.
Just to confirm you were talking about the diodes I selected with red ovals in attachment?

Thanks.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Do I need to unsolder one end of each diode for this test?

All tests can be done "in circuit". If the readings are suspicious, then you want to desolder one end and retest "out of circuit".

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Hi retired,
I have a question about 3. Do I need to unsolder one end of each diode for this test?
Thanks.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Voltages should all be stable and around 19V DC. This could indicate a problem with the caps on the power board being bad. For now, proceed to steps 3-6.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Update 1: I just checked the voltage again - all unsteady voltages are 18.84-18.88 now.
Update 2: Turned off - Turned on the monitor - unsteady voltages are back.
Update 3: After some time while power was on the voltages became steady.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

I am back.

Here are first results.

1. On CN702 connector everything is:
CN contact - Noname contact - 18.84V
CN contact - TP713 - 18.84V
CN contact - TP714 - 18.09-18.84V (unsteady)
CN contact - TP716 - 18.84V

See the first attachment.

2. U shape connectors, 12 contacts:
TP31 - TP32 - 18.88V
TP31 - TP33 - 18.84V
TP31 - TP34 - 17.07-18.84V (unsteady)
TP31 - TP35 - 15.55V
TP31 - TP36 - 14.70-18.00V (unsteady)
TP31 - TP37 - 17.32V
TP31 - TP38 - 18.88V

See the second atachment

I think the voltage should not be unsteady there. Is there anything I can check at this point or just to keep going to number 3?

Thanks a lot.

[dobber]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Not that it is the same, but I had a 17 in dell that did that, and it was bad caps on the Logic board.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Whoops typo for 4) above.

For the USB board, there is 1 voltage regulator and 4 transistors (J598). Check both for shorts.

6) There are 5 fuses on the USB board. Check them all. A good fuse should measure under 1.0 ohms.

So lots of things to check. Take your time and work carefully not to short out any of the components when power is ON.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Thanks, Retired. I will try to do that tomorrow (the monitor is at work).

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Okay, on the power board, there is connector CN702 which connects to the logic board.

1) Measure and report all the DC voltages for each pin/color.

2) On the logic board to the USB board, there is a 12 pin U shaped connector. Measure and report all the DC voltages for each pin. Careful not to short out anything here.

3) On the USB board, there are a number of diodes (I count 8). With power off and lcd unplugged, test them "in circuit" to see if they are bad with the diode test function.

4) There are 4 voltage regulators on the USB board. With power off and lcd unplugged, test to see if pins 1-2, 1-3, and 2-3 are shorted. Any ohms reading under 30 suggests a short.

5) There are 2 voltage regulators on the logic board. With power off and lcd unplugged, see if they are shorted.

[tboxxx]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Yes, do you have a multimeter? Do you know how to use it to measure resistance and DC voltage? If not, we can provide instructions.

Yes, I can find multimeter in the office. And I know how to measure both.
Thanks for the reply.

[retiredcaps]

Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

Any ideas what can be wrong or what should I check first?

Yes, do you have a multimeter? Do you know how to use it to measure resistance and DC voltage? If not, we can provide instructions.