samsung 305t caps bad?

[fordry]

I have a samsung 305t monitor which I got real cheap from craigslist. I have noticed that the backlight flickers some and it also seems to cause cfl bulbs in my room and the hallway next to my room to flicker when it is on. I looked around here and decided to open it up and have a look at its capacitors.

I realize you can't always see problems but there are 2 rubycon yxg capacitors that look ok other than I can see the rubber at the bottom sticking out further than the coating(? don't know capacitor terminology but by coating i mean the shell on the side... lol). I don't see any other issues with them, no bulging at all and all the rest of the capacitors look ok anyway. I'm wondering if these are indeed bad. not sure I could get good pics, its pretty tight spacing and the light has to be perfect to see under the capacitors at all.

Guess i would also be curious if anyone knows what other issues would cause these symptoms.

[fordry]

Re: samsung 305t caps bad?

hmm, looks like those caps are made that way. basically looks like these and these are supposed to be brand new ones.

[retiredcaps]

Re: samsung 305t caps bad?

Guess i would also be curious if anyone knows what other issues would cause these symptoms.

1) Possibly dodgy solder joints near the AC plug? Or in the inverter transformer area?

2) If you are going to post pictures, please follow the sig file below exactly.

3) I think the correct term is "bung".

4) If you have a multimeter, see if the DC voltages are stable and not fluctuating.

[fordry]

Re: samsung 305t caps bad?

hmm, i'm not really an expert with electronics and a quick google search didn't answer this question. how do i test the dc voltage? what points am i testing exactly?

[retiredcaps]

Re: samsung 305t caps bad?

how do i test the dc voltage? what points am i testing exactly?

Post clear top down view pictures of all your boards (front and back). Follow my sig file instructions exactly and then we can point out test points. Please no inline pictures.

[pgi]

Re: samsung 305t caps bad?

Fordry,
I have the same monitor, same symptoms. I just replaced all of the caps, no change. There is an online poker site that was discussing the problem. Apparently the monitor was a favorite for the aforementioned hobby. If you google "calling all 305t" the site and threads come up. Mine is going to autopsy after failed recapping.

[severach]

Re: samsung 305t caps bad?

The Samsung 305t uses the same LTM300M1C8LV3.2 T-Con board as the Gateway XHD3000. Problems from this board manifest as flashing rectangles and bars of solid color or altered hue. In the early stages the fault can look just like a lightly flickering backlight. The fix is to reball the Altera HardCopy HC1S30F780NAE or replace the T-Con board. Any fix where long life is expected requires a fan mod. I used two 12v 80mm fans from bad ATX power supplies in my Gateway XHD3000.

A T-Con fault won't cause the hall light to flicker. For that we need a power supply problem and I see there is one that could fit the bill. No pics are posted yet so I can only guess that your power board is part number BN96-03938A.

Overclock.net: My 30" Samsung 305T just popped

The FSD211H ICS801S is affected by the Fairchild vs. Power Integrations patent lawsuit (pdf) so you won't be buying the chip if that's the problem.

Service manuals are available. Search Badcaps.

[jadawgis732]

Re: samsung 305t caps bad?

I am an owner of a Samsung 305T which is also having issues with a flickering display. I think it is a power supply issue, because it seems to be a common problem on this display, and because my hall lights are flickering too.

I've contacted Samsung about acquiring a replacement, but they replied that they did not produce the monitor anymore, and despite my warranty being good through 1/2014, I would need to contact the eBay seller (who is no longer on eBay) in order to get the information about the primary owner.

So, I've resolved to repair it myself. Here I have an image showing the PSU board. Can someone direct my attention to which caps (if any) are bad. I am handy (relatively speaking) with a soldering iron, but I'd still prefer not to have to replace every cap. Any and all help would be greatly appreciated.

Here is a large version: http://img843.*************/img843/8...09062large.jpg

[fordry]

Re: samsung 305t caps bad?

Thought I would come back and update what has happened with my monitor. I just let it go and it stayed the same for a while.

About a month ago it "died". It would output for a split second then go blank for several seconds then flash on again for a split second and on and on. Totally unusable. I kinda figured it was the power supply with the whole house light flickering issue and then a seemingly power related problem with the monitor.

Finally got to reading about the issues with the tcon board and the alterra chip solder problem. Saw in another post that a couple people had baked their tcon boards in the oven and successfully fixed flickering issues among other issues. Since I have actually successfully baked laptop motherboards with Nvidia graphics chips (they also had a big issue with some of the 7xxx and 8xxx series chips) with success it didn't seem like to bad of an idea to try.

So I baked the tcon board in the oven at 375F for 8 minutes. When I hooked it back up and tested it out, it wasn't flashing on and off, but it was showing full screen lines for everything, similar to some of the issues people have talked about with the alterra chip problem in other places, so I baked it again for another 8 minutes. That did it, its working great.

I also decided after seeing the fan and heatsink mods to go ahead and go that route myself since I had a 120mm fan and several heatsinks laying around, hooked up the fan to a usb wire and plugged it into the computer. It is staying very cool on the back now where it used to get very very hot and the flickering it used to do, including the flickering of house lights in the same room and hallway where it is used, is not existent.

Hope this helps anyone else looking for information on problems with these monitors.

[sj4x4]

Re: samsung 305t caps bad?

Hello Fordry, sorry my bad english, i hope u understand me.
i have same ur problem with 305t.
If i understand good, i must put my LTM300M1 in elettric oven for 8 minutes at 375°F?????? but so all weld melt !!!

Thanks

[jerdobi]

Fixed a fast screen flicker

I had the flicker problem with a 305T and of course started with the replacing the electrolytic capacitors hoping for the quick and easy fix. That didn't work so I proceeded to the next fix to reheat the Altera Hardcopy chip and to my surprise it worked like a charm.

Process:

1). Remove the T-Con board that has the Altera chip on it. Be careful removing the connectors as one of the was even glued on.
2). Purchase some KESTER 186 ROSIN on EBay. The same stuff used to reflow an Xbox 360 or PS3.
3). Have access to a heat gun that has a low speed and a FLUKE multi-meter with a temperature probe.
4). Slowly use the heat gun to heat up the center of the board to 80-90 degrees Celsius.
5). Use some tin foil and cut out a hole just a 1/4 inch bigger than the chip to protect the other components from the heat.
6). Position the probe tip to be just on top of the chip within 1mm (closer the better).
7). Add a lot of the KESTER 186 ROSIN (it's like water) to around the Altera chip so it flows completely under the chip.
8). Put the heat gun on low speed and position about 3 inches from the chip and heat it up till the flux starts boiling. Then I put it down within 1 inch and heated the chip to about 265 Celsius for about 2 minutes. My heat gun would not get the chip any hotter than 265 C.
9). Remove heat and let T-Con board cold down without touching it until back to room temperature.
10). Re-install T-Con board.

When I examined the chip on the T-con board before the reheat the chip was standing up and the solder balls could be seen under the chip and were like balls. After the reheat the chip settled down on the board closer and flattened out quite a bit.

[jerdobi]

Fixed a fast screen flicker

I had the flicker problem with a 305T and of course started with the replacing the electrolytic capacitors hoping for the quick and easy fix. That didn't work so I proceeded to the next fix to reheat the Altera Hardcopy chip and to my surprise it worked like a charm.

Process:

1). Remove the T-Con board that has the Altera chip on it. Be careful removing the connectors as one of the was even glued on.
2). Purchase some KESTER 186 ROSIN on EBay. The same stuff used to reflow an Xbox 360 or PS3.
3). Have access to a heat gun that has a low speed and a FLUKE multi-meter with a temperature probe.
4). Slowly use the heat gun to heat up the center of the board to 80-90 degrees Celsius.
5). Use some tin foil and cut out a hole just a 1/4 inch bigger than the chip to protect the other components from the heat.
6). Position the probe tip to be just on top of the chip within 1mm (closer the better).
7). Add a lot of the KESTER 186 ROSIN (it's like water) to around the Altera chip so it flows completely under the chip.
8). Put the heat gun on low speed and position about 3 inches from the chip and heat it up till the flux starts boiling. Then I put it down within 1 inch and heated the chip to about 265 Celsius for about 2 minutes. My heat gun would not get the chip any hotter than 265 C.
9). Remove heat and let T-Con board cold down without touching it until back to room temperature.
10). Re-install T-Con board.

When I examined the chip on the T-con board before the reheat the chip was standing up and the solder balls could be seen under the chip and were like balls. After the reheat the chip settled down on the board closer and flattened out quite a bit.

[GnatGoSplat]

Re: samsung 305t caps bad?

I have a 305T which I suspect has the same problem. I do have a hot air rework gun, but not much experience using it. Anyone have any suggestions on what temperature I should use, how far away from the Altera chip I should point it, and for how long?