Gateway FPD2485W - capacitor related?

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

The numbers are:
9985GM
645032
Is there a way to test for proper voltage or resistance, or do you just replace suspected bad items? What is it you see that makes you think they've gotten hot? Now that I'm looking closer, there does appear to be a little golder brown tint to them. Is that what you're going off of?

[seanc]

Re: Gateway FPD2485W - capacitor related?

We can test with a multimeter, the results could be affected by other components in circuit.

The datasheet can be found: http://www.alldatasheet.com/datashee.../AP9985GM.html

You can test as a diode.

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

seanc, I looked at the datasheet and to be honest I wasn't 100% sure what to check. I checked the resistance between pins each pin on opposite sides ie pin1 with pin 8, pin 5 and pin 4. I then reversed the polarity of the leads. From pins 1 and 8 there is 1.6 ohms, from pins 2 and 7 1.6 ohms and pin 3 and 6 had 1.6 ohms (all in both directions) when I tested pins 4 and 5 there was a difference in ohms when switching direction of leads and it as 1.84 in the 20K ohm range and 5.14 in the other direction. Now MOSFET Q1 was the exception. On pins 4 and 5 it read 11.6 ohms in both directions. Could this be the bad one? Or could they all be bad? I'm not sure if I even tested correctly. Thanks

[retiredcaps]

Re: Gateway FPD2485W - capacitor related?

I checked the resistance between pins each pin on opposite sides ie pin1 with pin 8, pin 5 and pin 4. I then reversed the polarity of the leads. From pins 1 and 8 there is 1.6 ohms, from pins 2 and 7 1.6 ohms and pin 3 and 6 had 1.6 ohms (all in both directions) when I tested pins 4 and 5 there was a difference in ohms when switching direction of leads and it as 1.84 in the 20K ohm range and 5.14 in the other direction.

I test FETs by using measuring ohms between S-G, G-D, S-D. Any ohms reading below 20 ohms suggests it may be shorted.

I say, "may be", because if it is tested "in circuit", other components surrounding the FET could be causing false readings.

Your readings and looking at the datasheet suggest the MOSFET may be shorted, but I cannot be 100% sure unless it is tested out of circuit.

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

I'm attempting to remove one of them to test out of circuit. I have a desoldering iron with the squeeze bulb and a regular soldering iron. Any tips on how to remove this without ruining anything else? The leads on the MOSFET are small and all close together.

[retiredcaps]

Re: Gateway FPD2485W - capacitor related?

I'm attempting to remove one of them to test out of circuit. I have a desoldering iron with the squeeze bulb and a regular soldering iron.

I don't have the skills or equipment to offer any advice on how to remove the mosfets. However, CuriousInventor on youtube has some excellent soldering videos.

http://www.youtube.com/user/CuriousInventor

Also, BEFORE you desolder the mosfet, wait to see if others concur that mosfet might be shorted. I hate for you to go through all that work if I'm wrong.

[Wrog]

Re: Gateway FPD2485W - capacitor related?

One problem I have is I don't know how this monitor behaves when it does work. Is there someone who is familiar with this monitor? Does it normally turn itself on, or at least play the music when it is first plugged in, or do you have to push the power button?

As soon as you plug in the monitor, you should get the audio chime, along with a Gateway splashscreen while it detects any available video signals. When you said you replaced the caps already, did you use what others did in this thread (Panasonic FC or FM)?

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

Hi Wrog, I used some Panasonic and some Nichicon depending on what was in stock. Some of the caps are the same part #'s as listed, and some are not. Like I said, I replaced every cap on all the boards but one, and I didn't see a list from anyone doing all caps before. I can give you the part #'s if that would help.

[Wrog]

Re: Gateway FPD2485W - capacitor related?

Hi Wrog, I used some Panasonic and some Nichicon depending on what was in stock. Some of the caps are the same part #'s as listed, and some are not. Like I said, I replaced every cap on all the boards but one, and I didn't see a list from anyone doing all caps before. I can give you the part #'s if that would help.

Replacing all of the caps as you did is good practice, so you don't have to re-open the monitor in 6 months. Do you recall which series you used on both the Panasonic and Nichicon (or part #'s if that's easier)? It's important that they are low ESR and can handle high ripple (at or higher than originals). Have you verified proper voltages coming out of the power supply to the inverter board (measured at the connector)?

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

Hi, I looked up the part#'s on digikey and the series vary. I wasn't aware that the series mattered provided the uF and voltage were correct. I tried to select the ones with the longest hour rating with the 105 deg. rating. Here are some of the series for Panasonic... KG, EB, PW and FM. For the Nichicon I have PW, TS, and TT. I have not verified proper voltages going to the inverter board because I don't know what they should be and what wires to test. There is one red wire and 7 black wires. I did discover that the fuse (F1) on the inverter board was blown. I have a temp fuse there now, but when I plug it in with the fuse, the monitor doesn't make the audio chime. I never have gotten anything to display. Do you think the caps I selected based on the series could be the problem?

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

In looking at 2 of the part #'s that I used which were successfully used by others - P13478-ND and 493-3288-ND they are EB and TS series, so perhaps that doesn't matter too much.

[Wrog]

Re: Gateway FPD2485W - capacitor related?

Hi, I looked up the part#'s on digikey and the series vary. I wasn't aware that the series mattered provided the uF and voltage were correct. I tried to select the ones with the longest hour rating with the 105 deg. rating. Here are some of the series for Panasonic... KG, EB, PW and FM. For the Nichicon I have PW, TS, and TT. I have not verified proper voltages going to the inverter board because I don't know what they should be and what wires to test. There is one red wire and 7 black wires. I did discover that the fuse (F1) on the inverter board was blown. I have a temp fuse there now, but when I plug it in with the fuse, the monitor doesn't make the audio chime. I never have gotten anything to display. Do you think the caps I selected based on the series could be the problem?

The Panasonic FM is an excellent choice, along with the Nichicon PW. The others I'm not so sure about. Mismatched spec caps can cause what you are seeing. I would post a list of what you've purchased so someone more experienced than I can tell you which should be replaced with something more suitable. A lot of folks recommend Panasonic FC or FM series for this application.

As for the voltages on the inverter connector, measure the red against ground (use a screw hole on the pcb, or the black wires on the same connector). This should be done using VDC setting on your DMM. Proper voltage reading is probably between 12VDC - 24VDC, so set an appropriate range if your DMM is not automatic.

In looking at 2 of the part #'s that I used which were successfully used by others - P13478-ND and 493-3288-ND they are EB and TS series, so perhaps that doesn't matter too much.

The Nichicon TS looks suitable, but the Panasonic EB does not.

[PlainBill]

Re: Gateway FPD2485W - capacitor related?

I'm attempting to remove one of them to test out of circuit. I have a desoldering iron with the squeeze bulb and a regular soldering iron. Any tips on how to remove this without ruining anything else? The leads on the MOSFET are small and all close together.

Far and away the best way to remove these is with a hot air SMD rework station such as the KADA 852D. Second best, and a lot cheaper is a product called Chip-Quik. It's a low melt alloy (Woods metal) that mixes with the solder and lowers the melting point. I recommend solder wick to clean up the residue, although I have done acceptable work with a soldering iron and a solder sucker.

PlainBill

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

Attached is the order sheet for the parts I installed. Even though the EB series may not be ideal, the part P13478-ND was listed from someone else as being used and fixing the monitor, so I would assume it would be ok for mine. After removing one of the power mosfet (Q1) I tested from S-G, G-D and S-D as suggested and they were all less than 11 ohms, so it appears to be bad. The other 3 still on the board don't do this, so they may be ok.

[Wrog]

Re: Gateway FPD2485W - capacitor related?

The Nichicon PW and HE are great, the Panasonic FM is great, the EB are questionable. One that concerns me is the Panasonic KG (P910-ND), the ripple is low (47mA) and the ESR is high (10 ohms). The Nichicon PW (493-1767-ND) would be much better here. I honestly don't know about the Nichicon TS and TT series, hopefully someone will chime in about those. It looks like you've confirmed a problem elsewhere with a FET, hopefully that will turn out to be the problem source.

[retiredcaps]

Re: Gateway FPD2485W - capacitor related?

After removing one of the power mosfet (Q1) I tested from S-G, G-D and S-D as suggested and they were all less than 11 ohms, so it appears to be bad.

This auction has ended, but this seller has them

http://cgi.ebay.ph/LOT-4-AP9985GM-99...-/200436930981

I believe the seller, ecking767, has a good reputation on this forum for selling geniune caps (not fakes).

You can always send the seller an email to see if he will relist. Depending on your soldering skills, you might want to get 2? Since this is a 24 inch monitor, I would personally spend the money to get it fixed.

edit: findchips.com can't find AP9985GM through any of the usual suppliers

[king_raptor]

Re: Gateway FPD2485W - capacitor related?

I emailed him and he says they are on order and should be available next month. Do you think there is a way to find a different part, say from digikey that essentially does the same thing? Even if I had to replace all 4, that might be the way to go.

[retiredcaps]

Re: Gateway FPD2485W - capacitor related?

Do you think there is a way to find a different part, say from digikey that essentially does the same thing?

I suggest emailing digikey and asking them if they can suggest a replacement for the AP9985GM.

I don't have the expertise to understand all the specifications and nuances of the chip to suggest a replacement.

[djfourmoney]

Re: Gateway FPD2485W - capacitor related?

I got the back off and took some pictures but they look like the others on page #3 there's no visible damage. No puffy Caps or any burn marks.

Where is the inverter located? Is it the other PCB board located under the alum sheet with two signal plugs coming from it?

I will post some pictures tomorrow during football, I have another race to watch at 7am. (FIA GT1)

[djfourmoney]

Re: Gateway FPD2485W - capacitor related?

I got the back off and took some pictures but they look like the others on page #3 there's no visible damage. No puffy Caps or any burn marks.

Where is the inverter located? Is it the other PCB board located under the alum sheet with two signal plugs coming from it?

I will post some pictures tomorrow during football, I have another race to watch at 7am. (FIA GT1)

Here the pic -

Raiders!