Samsung Syncmaster 305t

[BairamMese]

I've had this monitor couple years. Then suddenly one day, screen just suddenly turned black. Backlight was on, but nothing else. Sometime it came back to life for couple minutes after I computer boot, but always went back to black after awhile.

I searched for the cause, and found the "oven-guide". Decided to try it, disassembled the monitor, took the tcon board out, wrapped it in folio and cooked for 7 minutes, then put everything back together, and now it's working almost perfectly again.

While disassembling the monitor, I managed to break the 15-pin data cable connector connecting to tcon board, so while assembling it back together I had to plug some of the wires in "manually". So not sure if everything is connected perfectly there. I tried to search ebay for replacement for that cable, but couldn't find any. What is that cable actually called? Any idea where I can buy a new one?

Now the monitor starts and works fine, but 1/4 of the leftmost screen is now blueish color. Is this caused by "baking", or could it be faulty connection somewhere?

Thanks in advance.

[selldoor]

Re: Samsung Syncmaster 305t

Please post pictures using manage attachments so that they stay with the thread - I have added it EVEN THOUGH IT IS NOT YOUR BOARD.
If you consider one quarter of the screen is in error and there are four
ribbon cables at the bottom of the picture. It could be that one of these is just seated incorrectly or may be damaged or the socket may be damaged.
I would check that out first and post a good clear picture of bothe the
socket and cable on YOUR machine

[BairamMese]

Re: Samsung Syncmaster 305t

Thanks for your reply.

I'll check the ribbon cables connections and take some pictures of the boards tomorrow when I open the monitor again.

Any info about that 15-pin cable, where can I buy one?

[bluesc]

Re: Samsung Syncmaster 305t

Is it a solid blue, or does it slightly "flicker"? If it is solid blue, it would rather expect a completely disconnected cable, otherwise your baking operation might not have been fully sucessful. But overall both flicker/solid cases could be badly connected cable or badly connected BGA solder joints.

My Baking Temperature Advices, based on Altera recommendations:

I read some baking advices using a normal oven in other threads which were not really detailed. When looking at reflow profiles from Altera for lead-free solder (not sure which of the many are the exact correct ones though), they require at least 217°C up to a maximum of 245-260°C (and "pre-heat" of 150-200°C). So for you US people, this is a minimum of 423°F required for at least 60 seconds.

For more details you can check the Altera SMT Board Assembly Process Recommendations:

So from that, I would do the following with only a normal oven available:
- Test oven how long it takes from 150->200->220+ °C and note down
Then after the oven has cooled down:
1. Dial to 150-200°C so the time from it until 220 will be in the range of 60-120 seconds (depending on the times noted down earlier!)
2. Wait until oven is on temperature
3. Apply liquid flux around the BGA just before putting into the oven
4. Put PCB inside and dial to something around 220-240°C if possible, look at the clock
5. It should stay 60-150 seconds above 220°C, but keep no longer inside than 8 minutes
6. Maybe let it cool down with half-open oven door, it should not cool down faster than 6°C/second according to altera guide

Of course, if the oven temperatures are not as it claims, it can be a hard time getting it right, I would try to choose slightly higher temperatures always.

I will still need to do all this soon myself, as my SM305T plus has the green lines issue

I piggybacked on this thread because there are just TOO MANY SM305T threads. Why do people always start new ones?

[bluesc]

Re: Samsung Syncmaster 305t

Correction / Additional Information:
The Preheat-Temperature usually considers preheating the board itself and not the oven.
But as we don't want to completely (de-)solder all the components, it might not be ideal to do that.
Maybe a good idea would be to pack most of the board into tin-foil, then pre-heat the altera asic with hot air as a preheating measure.

On the other hand, it might be not a too good idea to put the board (which will be room temperature) in a >150C preheated oven, as it will put thermal stress on most components....

So none is ideal to do. But as some people got it "fixed" by normal baking oven, it might not be so critical after all.

[knoxrebel]

Re: Samsung Syncmaster 305t

I'm having jitter issues with this monitor which makes the picture fuzzy. Other than this no issues. Does this sound like a scaler issue?