Samsung Model 731N No Display

[ffvito]

Re: Samsung Model 731N No Display

Just to make you feel worse, you could live in the middle of Manhattan and the shipping costs from China would be the same.

PlainBill

Pon una resistencia de 47 Ohms entre las patas 5 y 6 del NT68F63 y problema solucionado.

[PlainBill]

Re: Samsung Model 731N No Display

When I say secondary monitor I mean plugged into the monitor port on my laptop and configured as a second monitor, configured as the primary monitor, and configured just to display/copy my laptop screen. However I also tried plugging it into a test desktop and still had the same issue.

I think I will buy the logic card from china. I figure the monitor working is worth around $100, so I should be able to go up to $60 to attempt and repair it. Between the voltage reg with shipping and the logic card with shipping I will have sent $42. Well worth the attempt so far. You remove shipping costs and I will have sent $13 Oh the joy of living in the middle of nowhere.

Just to make you feel worse, you could live in the middle of Manhattan and the shipping costs from China would be the same.

PlainBill

[browork]

Re: Samsung Model 731N No Display

When I say secondary monitor I mean plugged into the monitor port on my laptop and configured as a second monitor, configured as the primary monitor, and configured just to display/copy my laptop screen. However I also tried plugging it into a test desktop and still had the same issue.

I think I will buy the logic card from china. I figure the monitor working is worth around $100, so I should be able to go up to $60 to attempt and repair it. Between the voltage reg with shipping and the logic card with shipping I will have sent $42. Well worth the attempt so far. You remove shipping costs and I will have sent $13 Oh the joy of living in the middle of nowhere.

[MDOC]

Re: Samsung Model 731N No Display

Now that I've seen it, it appears likely that the monitor is expecting a signal, and seeing none, complains about it. My monitor does that. When you set this up as a second monitor, did you see an image display from the computer (not the error message)? If not, set it up as a sole monitor and see if it displays an image.

[browork]

Re: Samsung Model 731N No Display

Here is all the manual tells you about my error. The manual can be downloaded from the Samsung website here. The manual is in PDF format. The picture is taken from this manual on page 32 and I give Samsung full credit for it. I just wish it was more helpful. I am still looking for a schematic.

[MDOC]

Re: Samsung Model 731N No Display

How can I be out of range or whatever generates that message without a computer plugged in to send a signal to the monitor. Something is messed up and I figure it is one of the IC chips (if that's the right term).

Yes, you're right, there. I'm not familiar enough to know which chip to probe without a schematic.

[browork]

Re: Samsung Model 731N No Display

Hmmm...

Still the same message. I will say the monitor blanks and I guess restarts when I do this. The power and screen go off for a second than the power comes back on. It is doing something, but not fixing my issue and getting rid of the optimization message.

I'm with severach there, I think the over voltage damaged the video chip or something else on that board. I get the message the second the monitor comes on, with nothing (no computer) plugged in. How can I be out of range or whatever generates that message without a computer plugged in to send a signal to the monitor. Something is messed up and I figure it is one of the IC chips (if that's the right term).

As a side note, The guy from china emailed me back. He was willing to send me the whole logic board. I am still thinking about whether to order from him or not though.

[MDOC]

Re: Samsung Model 731N No Display

I just read up on this. Try this:

"..push the menu button and then the one with the arrow on it (4 from the left) and hold that one down for like 20 seconds. It seemed to work..."

this came from solution #2 here:
http://www.fixya.com/support/t318888...uto_adjustment

[browork]

Re: Samsung Model 731N No Display

Looks like you want me to hold down the menu key for 5 seconds. I tried that three times with no success

Have any other ideas?

[PlainBill]

Re: Samsung Model 731N No Display

Well it looks like my victory was not as short lived as severach it was shorter.

Digikey shipped the part the same day I ordered it, and I received it today. Once I replaced the voltage regulator I do actually get a screen... It reads "Not Optimum Mode Recommended Mode: 1280 x 1024 60 Hz." No computer is plugged into the monitor.

Just to make sure, I plugged a computer into the monitor and nothing changed, no matter the resolution or frequency I set it too (set up as a second monitor).

Therefore I guess this means I will need to replace the logic board if I want this monitor to work.

Unfortunately the only place I can find that sells it is in China. Now my Chinese is a little rusty (since I know next to none) and I am not sure how I would pay for the part (or if i should trust giving them my information in the first place). Here is a link to the site if your interested.

Does anyone else have any thoughts?

The part number is 490611300100R
Best I can tell the same board is in both the 720N and 731N models.

I've suggested this a lot lately. Google 'reset 731n monitor'. IF the problem is corrupted used EEPROM, this may allow you to reset it.

PlainBill

[browork]

Re: Samsung Model 731N No Display

Well it looks like my victory was not as short lived as severach it was shorter.

Digikey shipped the part the same day I ordered it, and I received it today. Once I replaced the voltage regulator I do actually get a screen... It reads "Not Optimum Mode Recommended Mode: 1280 x 1024 60 Hz." No computer is plugged into the monitor.

Just to make sure, I plugged a computer into the monitor and nothing changed, no matter the resolution or frequency I set it too (set up as a second monitor).

Therefore I guess this means I will need to replace the logic board if I want this monitor to work.

Unfortunately the only place I can find that sells it is in China. Now my Chinese is a little rusty (since I know next to none) and I am not sure how I would pay for the part (or if i should trust giving them my information in the first place). Here is a link to the site if your interested.

Does anyone else have any thoughts?

The part number is 490611300100R
Best I can tell the same board is in both the 720N and 731N models.

[MDOC]

Re: Samsung Model 731N No Display

So number 1 is bad and number 2 is good?

Correct.

[browork]

Re: Samsung Model 731N No Display

497-6868-1-ND IC REG LDO POS 800MA 1.8V SOT223 has been ordered...

Hopefully my victory is NOT as short lived as his was. After all, finding the bad voltage reg makes me pray my PSU is fine, where his was not.

Edit: I also have not noticed any excess heat of the video chip. We can pray.

[browork]

Re: Samsung Model 731N No Display

So number 1 is bad and number 2 is good?

[PlainBill]

Re: Samsung Model 731N No Display

As for the two voltage regulators.

Lets call the upper right one Number 1 and lower left one Number 2.

Number 1
Labeled
Line 1 A1
Line 2 AS1117L-18
Line 3 B0552

Voltages
Pin 1 0V
Pin 2 4.02V (unlabeled)
Pin 3 5.06V
Pin 4 4.02V


Number 2
Labeled
Line 1 A1
Line 2 AS1117L-33
Line 3 B0637 38

Voltages
Pin 1 0V
Pin 2 3.28V (unlabeled)
Pin 3 5.07V
Pin 4 3.28V

All voltages were measured to ground, in the lower left on the Monitor plug.

What's next....

Bad news. The AS1117L-xx chips are voltage regulators, supplying critical voltages to components on the logic board. The xx in the part number indicates the output voltage. -33 indicates 3.3 volts, -18 indicates 1.8 volts. Severach had encountered a similar problem in this thread. Note in that case the overvoltage had fried the video chip on his monitor. At this point I wouldn't bother replacing the caps. If a voltage regulator becomes available, I'd try it before replacing the caps. An equivalent part by STMicroelectronics (497-6868-1-ND) is available from Digikey (497-6868-1-ND) for $.75 each.

PlainBill

[browork]

Re: Samsung Model 731N No Display

All of those but two are XICON. The other two are nichicon (two of the 47uF 35V).

Are they any good quality? They have probably been in storage since I left the military. I have some monster caps too with screw terminals. No clue what I would ever do with them, but I am a little bit of a pack rat. You never know when I might use something, so if it is new or good I keep it.

For the smaller ones I also have some elgen, rubycon, jamicon and others. When I say I found a box, I mean I found about 300 small caps in several models and sizes.

Edit: And they all should fit fine. The biggest one is the 1000uF 35V, which is the exact same size as the 1000uF 25V that it is replacing. The one with the only size difference is the 1000uF 10V, but it sits next to the 1000uF 25V so it should not be any issue.

[MDOC]

Re: Samsung Model 731N No Display

Quick question...


I have...

2x 1000uF 35V
2x 470uF 35V
4x 47uF 35V

Would those work as replacements...
They are all the same size as the others (except the 1000uF 10V is smaller then the replacement 1000uF 35V).

Yep. Except the bigger cap for the 1000uF 10V might not fit, but if it does, then no problem.

Edit: Who's the manufacturer of those caps?

[browork]

Re: Samsung Model 731N No Display

4.8 volts is a little low. That could be an indication of bad caps. There are a couple of additional things to check, also. I've circled two voltage regulators on the logic card. Measure the voltage on each of the pins to ground (I've identified a point in the lower right corner of the board). Also, what are the part numbers of these regulators?

PlainBill

As a side note I am reading 5.07V on those pins today. Not sure why it's different.

[browork]

Re: Samsung Model 731N No Display

As for the two voltage regulators.

Lets call the upper right one Number 1 and lower left one Number 2.

Number 1
Labeled
Line 1 A1
Line 2 AS1117L-18
Line 3 B0552

Voltages
Pin 1 0V
Pin 2 4.02V (unlabeled)
Pin 3 5.06V
Pin 4 4.02V


Number 2
Labeled
Line 1 A1
Line 2 AS1117L-33
Line 3 B0637 38

Voltages
Pin 1 0V
Pin 2 3.28V (unlabeled)
Pin 3 5.07V
Pin 4 3.28V

All voltages were measured to ground, in the lower left on the Monitor plug.

What's next....

[browork]

Re: Samsung Model 731N No Display

Quick question...

While digging for my caliper I found a box of caps...

What is on the PSU is...

4x 47uF 25V
2x 470uF 25V
1x 1000uF 10V
1x 1000uF 25V

I have...

2x 1000uF 35V
2x 470uF 35V
4x 47uF 35V

Would those work as replacements...
They are all the same size as the others (except the 1000uF 10V is smaller then the replacement 1000uF 35V).

BTW, I found my caliper, but it is digital and needs batteries so I'll run back into town this afternoon and pick some up.