Gateway FPD2185W

[Wrog]

Hi again everyone! Finally got around to cracking open the dead (no power light at all) Gateway, and recapped all of the 220uF and 470uF SamXons. It still doesn't fire up -- there are no 5V or 12V outputs. When measured, it fluctuates between 0.5VDC and 1.2VDC or so on both lines.

Measured input voltage, steady 119.5VAC. The big boys (68uF 450V) measure 165VDC. Measured IC101 (identified as 200A6) pin 6 measures at 8VDC and pin 8 at 150-160VDC, which brings me to the power supply caps C103 (47uF 25V) and C113 (10uF 50V). These were not replaced in the first round, but parts are on order and should be here in a few days.

Are there any other tests that will help diagnose in the meantime? U301, U302, U304, U305 on the bottom side (identified as AOD405 and AOD408, two each) have scorched the PCB pretty good, but not sure if there's damage. What's the best way to test these? Thanks!

[PlainBill]

Re: Gateway FPD2185W

Hi again everyone! Finally got around to cracking open the dead (no power light at all) Gateway, and recapped all of the 220uF and 470uF SamXons. It still doesn't fire up -- there are no 5V or 12V outputs. When measured, it fluctuates between 0.5VDC and 1.2VDC or so on both lines.

Measured input voltage, steady 119.5VAC. The big boys (68uF 450V) measure 165VDC. Measured IC101 (identified as 200A6) pin 6 measures at 8VDC and pin 8 at 150-160VDC, which brings me to the power supply caps C103 (47uF 25V) and C113 (10uF 50V). These were not replaced in the first round, but parts are on order and should be here in a few days.

Are there any other tests that will help diagnose in the meantime? U301, U302, U304, U305 on the bottom side (identified as AOD405 and AOD408, two each) have scorched the PCB pretty good, but not sure if there's damage. What's the best way to test these? Thanks!

Thanks for providing the documentation. That makes it easier.

That fluctuation can be caused by two things. The most likely is a defective cap on the Vcc pin if the SMPS controller (pin 6). This is particularly likely because it appears they may have used a tertiary winding on the SMPS transformer to provide power for the SMPS controller. The other possibility is excessive load on one of the outputs. A simple ohmmeter test is the best way to check for that. Oh, a reversed cap would also do it.

As far as the inverter driver transistors, check them for shorts between all three terminals of each device. This can be done in circuit.

PlainBill

[Wrog]

Re: Gateway FPD2185W

Thanks PlainBill. I'm assuming the cap you are referring to on the Vcc pin would be either C103 or C113 (the ones that I am replacing)? I'll have to wait until the replacements arrive to test that aspect.

I saw in another posting (same monitor) where you were giving instructions on testing the inverter driver transistors. I will fill out the table for both continuity and bad junctions and report back later (wish I could bring this stuff in to work!).

I also neglected to mention that I have the main board disconnected at this point since it doesn't seem to respond to the power button. Should I reconnect it for any tests requiring voltage measurement? I seem to remember a discussion in another thread about some power supplies needing a load in order to start up.

Thanks again for all of the help, I'm learning more than I ever could imagine and having fun doing it!

[anno]

Re: Gateway FPD2185W

no need to connect mainboard. Maybe there is a short in the output diodes (on the heatsinks) . check them for short circuit.

[PlainBill]

Re: Gateway FPD2185W

Thanks PlainBill. I'm assuming the cap you are referring to on the Vcc pin would be either C103 or C113 (the ones that I am replacing)? I'll have to wait until the replacements arrive to test that aspect.

I saw in another posting (same monitor) where you were giving instructions on testing the inverter driver transistors. I will fill out the table for both continuity and bad junctions and report back later (wish I could bring this stuff in to work!).

I also neglected to mention that I have the main board disconnected at this point since it doesn't seem to respond to the power button. Should I reconnect it for any tests requiring voltage measurement? I seem to remember a discussion in another thread about some power supplies needing a load in order to start up.

Thanks again for all of the help, I'm learning more than I ever could imagine and having fun doing it!

It's always a good idea to have some sort of a load hooked up. In general a SMPS requires a load of at least a 10% of rated capacity to be stable.

In spite of other's opinions, shorted diodes on the output of these power supplies are quite rare. Bad caps are much more likely. A shorted diode would result in one output not even twitching. I don't think it's the inverter transistors, but they are easy to check.

PlainBill

[Wrog]

Re: Gateway FPD2185W

Update: Inverter transistor measurements.

Continuity test (200 ohm setting)

Transistor  G – D D – S G – S
U301 (AOD405) OL  OL  OL
U302 (AOD408) OL  OL  OL
U304 (AOD405) 32.9 0.04 33.0
U305 (AOD408) 5.3  0.9  4.9

Bad junctions (diode test setting, black on first lead, red on second)

Transistor G – D G – S D – G D – S S – G S – D
U301    OL   OL   1.303 0.571 0.970 0.628
U302    1.331 0.938 1.794 0.565 1.715 0.629
U304    0.033 0.033 0.033 0.000 0.033 0.000
U305    0.005 0.005 0.005 0.005 0.005 0.001

[Wrog]

Re: Gateway FPD2185W

Either I've forgotten everything about basic electronics, or this board is totally hosed (or both!). Measuring the diodes on the board results in the following:

Diode measurements (diode test setting, one measurement each direction):

D101: ∞, 0.590
D102: 1.825, 0.623
D103: ∞, 0.686
D104: 0.051, 0.051
D208: ∞, 0.687
D301: 0.075, 0.077
D302: 0.149, 0.149
D303: 0.074, 0.074
D304: 0.149, 0.149
D312: ∞, 0.685
D408: ∞, 0.683
D410: ∞, 0.693
ZD101: ∞, 0.915
ZD202: ∞, 0.854
ZD301: 1.171, 0.917
ZD302: ∞, 0.905
ZD303: 0.105, 0.105

If the output diodes are D205, D207 (both MBR10150CT) and D211, D212 (both SBL1060CT), they give strange readings also:

D205, D207 measure close to 0 (around 0.001) in all directions. D211 measures 0.407 across legs 1/2 and 0.123 in the other direction (then reversed for 2/3). These readings are repeated for D212.

[anno]

Re: Gateway FPD2185W

i mean the diodes on the heatsink. check with ohm meter/multimeter . the outer pins should show 0 ohm, they are usually connected to each other, the middle pin and outer pin should not show a short (around 0 ohm). but shoud give 03.04.05 or whatever in one direction. sorry if i don`t explain it very well.

[Wrog]

Re: Gateway FPD2185W

Update: Replaced the last two remaining caps C103 (47uF 25V) and C113 (10uF 50V), and no change on the 5V and 12V outputs. They both still fluctuate (0.2 - 1.4VDC).

PlainBill, can you describe the test you mentioned earlier about excessive load on one of the outputs? It looks like 5V and 12V goes to the mainboard and 5V goes to the USB hub.

Anno, I've checked D205, D207, D211 and D212 and here are the results. D205 and D207 measured the same, and D211/D212 also measured the same. These are measured with the tab away, pin 1 left, pin 2 center, pin 3 right:

D205/D207 (200 ohm scale, first pin black, second red):
1-2: 1.1
2-3: 1.2
1-3: 0.2
2-1: 1.2
3-2: 1.2
3-1: 0.2

D211/D212 (2k ohm scale, first pin black, second red):
1-2: 0.401
2-3: 0.266
1-3: 0.000
2-1: 0.266
3-2: 0.401
3-1: 0.000

Any additional troubleshooting direction would be appreciated!

[axxam enni]

Re: Gateway FPD2185W

I have the same monitor with exactly the same problem as yours. After dismantling and visual check, I came to the conclusion that unlike problems reported by many who successfully repaired their PS by changing the bad caps, mine was too damaged by heat to salvage. In fact, careful inspection reveals some delamination of the first board layer. It is really cooked. So I am looking for a replacement power supply either used or new. Or maybe one from a soul who does not care about repairing theirs. If you see any, I'd like to know. Else, if I discover something, I'd share with you.

[kc8adu]

Re: Gateway FPD2185W

u304 and 305 are shorted!

[Wrog]

Re: Gateway FPD2185W

I have the same monitor with exactly the same problem as yours. After dismantling and visual check, I came to the conclusion that unlike problems reported by many who successfully repaired their PS by changing the bad caps, mine was too damaged by heat to salvage. In fact, careful inspection reveals some delamination of the first board layer. It is really cooked. So I am looking for a replacement power supply either used or new. Or maybe one from a soul who does not care about repairing theirs. If you see any, I'd like to know. Else, if I discover something, I'd share with you.

Axxam, post pics of your power/inverter pcb (top and bottom using macro mode if your camera supports it). You never know, the collection of experts around here are quite adept at very helpful advice to diagnose and help repair! I've learned much more than I expected and hopefully will have another success story soon...

What are the steps you've taken so far to troubleshoot? I can help with some of the basic points of measurement since we have the same monitor; hopefully some of the experts can assist with the advanced stuff. I'll post an update on where I am in a separate reply.

[Wrog]

Re: Gateway FPD2185W

u304 and 305 are shorted!

Absolutely right -- probably obvious to most everyone here (but me) based on those measurements, but it took several weeks of poking and probing (and asking an expert privately). Once these two inverter transistor leads were clipped (U304, U305), voltages stabilized to the main board at 5V and 12V. So PlainBill was right waaay back in post #2 about the excessive load (transistor short) shutting down the DC voltage.

Just in case anyone else runs into this with theirs, all four transistors were replaced as follows:

U301, U304 (AOD405) -> AOD417; Digikey P/N 785-1106-1-ND
U302, U305 (AOD408) -> AOD484; Digikey P/N 785-1114-1-ND

[Wrog]

Re: Gateway FPD2185W

The latest progress with this monitor...

After all caps and inverter transistors replaced, the power/inverter board tests fine with the logic board and panel from another monitor! When I put mine back together, I get the Gateway logo for about 1 second, then black. The power LED stays blue for about 5 seconds, then orange (sleep). If I hook up a video source, the power LED remains blue.

From reading some of the other threads here about similar problems, it seems to be a bad CCFL bulb... so I disassembled the panel, and found that many of the return wires on them had disintegrated insulation at the ends (4 of the 6), probably due to heat?

My question now is... what is the most effective/efficient way to test individual CCFL bulbs? I thought I read in another thread here that some prefer to use an inexpensive CCFL mod kit (like from eBay) but I don't know if the specs match up between the two types of CCFLs (12VDC in, 680VAC out?). Are there any other simple ways? Also, I don't suppose anyone has the measurements of these CCFLs? I've tried to google it since I don't have a micrometer, but no luck.

If multiple CCFLs are bad, it's going to start getting expensive to repair... maybe Axxam will skip repairing his and have some for sale. On the other hand, if I can't get the proper CCFLs for mine, maybe I'll have a power/inverter board for sale!

[Wrog]

Re: Gateway FPD2185W

Well, after 6 weeks, we have another success story... it's alive! Replacing all 6 CCFLs did the trick after the previous fixes (total recap on the power/inverter board, replaced four inverter transistors). I didn't know how to test each CCFL individually; maybe that's an exercise for another day. A couple of points of information in case anyone is searching for info on this model:

- The panel is a Samsung LTM210M2-L02, with CCFLs that are 2.6mm diameter at a length of 460mm. A good place to buy them is from ccflwarehouse.com, but don't order from their website (@$11.95 ea). The same company has an ebay auction up (search for "460mm ccfl" and you can get them for $8 ea, probably other sizes too).

- The return wire is 28 AWG. ccflwarehouse.com can also supply this, though its very expensive in small quantities ($1 / ft).

I wasn't able to re-use the endcaps on the return wire end because they pretty much fell apart during disassembly. ccflwarehouse.com can supply either generic (single) or fitted (multi-bulb) silicone endcaps for like $1 ea. They actually included four triple endcaps that almost fit the CCFL channel; I had to trim it down slightly to fit.

Thanks to everyone who puts in their time here to help educate, I really appreciate it -- particularly PlainBill. I think I've read every single one of your posts at least twice!

[smason]

Re: Gateway FPD2185W

Well, after 6 weeks, we have another success story... it's alive!

Awesome! Glad you persevered, it's always rewarding once done.

Thanks to everyone who puts in their time here to help educate, I really appreciate it -- particularly PlainBill. I think I've read every single one of your posts at least twice!

No chit! Dude deserves a medal, and a few cases of beer! mmm beeeer

[PlainBill]

Re: Gateway FPD2185W

Aww, guys, I'm blushing. I appreciate the kind words.

PlainBill

[krubil]

Re: Gateway FPD2185W

[QUOTE= Replacing all 6 CCFLs did the trick after the previous fixes (total recap on the power/inverter board, replaced four inverter transistors). I didn't know how to test each CCFL individually; maybe that's an exercise for another day. A couple of points of information in case anyone is searching for info on this model:
[/QUOTE]

I found FPD2185 in recycle bin today.Brought it home,Looks like shorted outputs.Power LED blinks for very short time,First I have to open the damn thing.I'll let you guys know how I make out.Monitor does look very slick,didn't think I would find it in Recycle Bin.

[krubil]

Re: Gateway FPD2185W

Guys,
Replaced 8- 470ufd,25V(SAMXON) with XICON Caps and that was it.Cost of STARBUCKS Venti and hour of Soldering and Desoldering.By the way XICON Caps can be procured at ALL Electronics (excellent source of surplus).

Krubil

[bluto]

Re: Gateway FPD2185W

I just got a another one of these from a colleague to work on. Only two of the 470uf caps are bulged. None of the 4 driver transistors are burnt/shorted. The symptoms were that the monitor was shutting down after a short time. I went ahead and ordered all 12 caps for the power supply. I just hope its not the CCFLs.