Gateway FPD2185W not showing display

[yashua]

Re: Gateway FPD2185W not showing display

This is unfurtunate because I have an automatic meter... that beeps with continutiy.

[yashua]

Re: Gateway FPD2185W not showing display

On the backside are 4 mosfets. I can only make out one part number which is U304. The other 3 look like U304.

Testing a mosfet procedure at

https://www.badcaps.net/forum/showpo...4&postcount=19

Here is a better cose up shot

[budm]

Re: Gateway FPD2185W not showing display

http://s807.photobucket.com/albums/y...t=DSCF1563.jpg

The picture and the notes show the P/N and designators of the 4 MOSFET's.

[retiredcaps]

Re: Gateway FPD2185W not showing display

This is unfurtunate because I have an automatic meter... that beeps with continutiy.

Testing for shorts using the contunity feature instead ohms is a highly inaccurate. Some very cheap multimeters will "beep" if the ohms reading is less than 1800 ohms.

So if your pin combination reading is 1700 ohms, your multimeter is saying it is shorted when it is not.

I would say less than 1% of the people who use a multimeter actually know what the threshold of their continuity beeper is.

Use the ohms scale ALWAYS.

Now having said all that, it is highly likely your mosfets are bad.

[yashua]

Re: Gateway FPD2185W not showing display

Testing for shorts using the contunity feature instead ohms is a highly inaccurate. Some very cheap multimeters will "beep" if the ohms reading is less than 1800 ohms.

So if your pin combination reading is 1700 ohms, your multimeter is saying it is shorted when it is not.

I would say less than 1% of the people who use a multimeter actually know what the threshold of their continuity beeper is.

Use the ohms scale ALWAYS.

Now having said all that, it is highly likely your mosfets are bad.

umm not to be rude but my meter isnt cheap and I did not test it becuase that method is highly inacurate. That's why I stated it was unfourtunate that I don't have a selectable meter.
with that being said- I can bet good money it isn't these, but its what was asked of me to check... so I abliged in trying to check.

EDIT- Threshold: On at <25 Ω, off at >400 Ω... Just so you don't think I am your 1%.....

[budm]

Re: Gateway FPD2185W not showing display

I am sure your meter has auto-range, but I am sure you can select the Ohm mode or Continuity mode, $300 FLUKE in the Beeping mode will beep with any resistance less than 50 Ohms. I use Ohm mode to look for short.

[yashua]

Re: Gateway FPD2185W not showing display

Can we step away from the mosfets and try something else. I remember when you were saying that since my lights are half glowing it could be an undercurrent issue. Is there a way to confirm that... I am trying to find the problem before I have to put it all back together before I move then once moved in I will be able to dissaseamble and hopefuly at that time I will have the correct part and change it out.

[yashua]

Re: Gateway FPD2185W not showing display

$300 FLUKE in the Beeping mode will beep with any resistance less than 50 Ohms. I use Ohm mode to look for short.

Just to clarify that is an innacurate statement- here are the specs for my meter
Threshold: On at <25 Ω, off at >400 Ω

[yashua]

Re: Gateway FPD2185W not showing display

[QUOTE=budm;221401]I am sure your meter has auto-range, but I am sure you can select the Ohm mode or Continuity modeQUOTE]

I agree with you about that... Unfourntunatley there really arent a lot of buttons on my meter. It is completly auto and only has one button (hold) other than that I am not quite sure how to change modes if I even can

[retiredcaps]

Re: Gateway FPD2185W not showing display

umm not to be rude but my meter isnt cheap and I did not test it becuase that method is highly inacurate.

Look, I didn't say your Fluke was cheap. I'm just saying that using continuity for checking shorts is not accurate.

Just remember who is trying to help who.

[retiredcaps]

Re: Gateway FPD2185W not showing display

Now having said all that, it is highly likely your mosfets are bad.

And just to clarify my statement above, I thought you had already checked the mosfets by using the continuity feature and got beeping.

If you haven't tested the mosfets, then obviously we don't know if they are good or bad.

[budm]

Re: Gateway FPD2185W not showing display

What you can do for now is to leave the lamps out of the LCD panel assembly for now and put the panel in place that way you will have a way of testing the lamps, Inverter-power supply combo board after the repair is verified.I will not try to run the board untill you have Ohm out all the MOSFET's, we do not want to cause any more damages to the board. That is my suggestion. We would like to know the resistance reading not just the beep to verify the MOSFET's are good or not since the circuits may have low value resistors connected around the MOSFET's pins.

[retiredcaps]

Re: Gateway FPD2185W not showing display

It is completly auto and only has one button (hold) other than that I am not quite sure how to change modes if I even can

Here is a snapshot of the instruction sheet from

https://cdn.badcaps-static.com/pdfs/...660650b566.pdf

When the circuit is open, it shows 0L. When closed, it shows 0 ohms.

If the reading is less than 1000 ohms, it shows the reading. If it is less than 25 ohms, it beeps.

Now if the mosfet is shorted, it might read 35 ohms. The Fluke won't beep, but the display will show 35 ohms. This reading suggests the mosfet is shorted and should be desoldered and retested out of circuit.

If the Fluke shows 0L, then the reading is greater than 1000 ohms and suggests the mosfet is not shorted.

The resolution for the ohm scale is 1 ohm.

[yashua]

Re: Gateway FPD2185W not showing display

all I get is 1 and a beep on all 4 mosfets.
I am not sure of the order of pins to check so I checked all of them and the one in the middle and on the opposite side of the chip are what gave me a reading of 1 on all 4

[yashua]

Re: Gateway FPD2185W not showing display

Look, I didn't say your Fluke was cheap. I'm just saying that using continuity for checking shorts is not accurate.

That I definetly agree with

[retiredcaps]

Re: Gateway FPD2185W not showing display

all I get is 1 and a beep on all 4 mosfets.
I am not sure of the order of pins to check so I checked all of them and the one in the middle and on the opposite side of the chip are what gave me a reading of 1 on all 4

Checking a 3 pin mosfet is done like this.

Number the "bottom" pins 1, 2, and 3. Ignore the top fat tab.

Measure the resistance between pins 1-2, 1-3, and 2-3.

PS. The fat tab and the opposite pin (middle pin) are electricaly connected so it show 1 ohm.

[retiredcaps]

Re: Gateway FPD2185W not showing display

That I definetly agree with

Look I have 3 Flukes and I bought them all used and they still cost more than the average multimeter. I'm trying to explain concepts to you and whoever else might be following along or reading this in the future.

[yashua]

Re: Gateway FPD2185W not showing display

Look I have 3 Flukes and I bought them all used and they still cost more than the average multimeter. I'm trying to explain concepts to you and whoever else might be following along or reading this in the future.

I am not sure why you went all commando, I was agreeing with you... I am kinda puzzled? I appreciate your help and have already put your suggestions to use, so umm... Thanks Again!