Samsung 910t

[joshuashsong]

Re: Samsung 910t

Attached are the IP board with original capacitor. (DSCN4863.jpg)

After replaced with 4X Low ESR Suntan CD286 1000uF 25V, for 2X Samxon GF series 1000uF 25V & 2X Samxon GF series 1000uF 16V capacitor. Also replaced 1X Low ESR Suntan CD286 470uF 25V for the Samxon GF series 470uF 25V. (DSCN4885.jpg)

The following is the voltage measurements on the CN600

Pin 1 - 12.3V wrt pin 5
Pin 2 - 12.3V wrt pin 5
pin 3 - 0V
pin 4 - 0V
pin 5
pin 6 - 5.02V wrt pin 5
pin 7 - 5.02V wrt pin 5
pin 8 - 1V wrt pin 5
pin 9 - 3.36V wrt pin 5

The problem still remained the same, it goes to sleep mode (blank screen) when detected input signal on both Analog or Digital.

Attached is the Signal processing board. (DSCN4888.jpg) Just wondering whether I should try the following suggestion: attached a 50 ohm resistor across pin 5 & 6 for Novatek NT68F63LG IC?

[Wizard]

Re: Samsung 910t

Try a new serial EEPROM (8 pin) that is next to blue VGA connector on left. I cured a generic LCD monitor this way. Use exact same part number but not have to be same brand. like 24C16 for 24C16 for example, what is the marking on yours?

Cheers, Wizard

[Bobdee]

Re: Samsung 910t

Try a new serial EEPROM (8 pin) that is next to blue VGA connector on left. I cured a generic LCD monitor this way. Use exact same part number but not have to be same brand. like 24C16 for 24C16 for example, what is the marking on yours?

Cheers, Wizard

Wizard
Your da man
You are a Magician
I read your post and it makes sense
This thread that is a diffrent Samsung model
https://www.badcaps.net/forum/showth...ung+syncmaster
and another diffrent model again that I have and
also a SAMTRON that I have (that I am sure that is a Samsung under a diff name
We all have the same Mainboard but not exactly the same symptoms
But one symptom that we all got is that when we connect to comp we get black screen
I have also found that by process of elimination that when I short AVG pin 10 to monitor housing that I recreate the same symptoms as if I had connected a VGA to comp =(blank screen)
Also I have measured for voltage from pin 10 to housing and got 4.64v Dc that I suspect is about right
(I cannot give my model numbers right now as my 2 grandaughters are sleeping over the top of them)
??? Does any of this make sense to you ???

[Wizard]

Re: Samsung 910t

I don't advise the voltage hack, it hide the dying chip.

Either the microcontroller (the 44 pin square) or the EEPROM (this serves to hold customer settings.). I had to replace the microcontroller on Samsung LCD I have, since had sold it to my friend who is happily using it.

Give me exact model CODE from the sticker and I can look it up for part number on this microcontroller. Re the eeprom, change it with a blank one and see how it goes.

Cheers, Wizard

[joshuashsong]

Re: Samsung 910t

Try a new serial EEPROM (8 pin) that is next to blue VGA connector on left. I cured a generic LCD monitor this way. Use exact same part number but not have to be same brand. like 24C16 for 24C16 for example, what is the marking on yours?

Cheers, Wizard

It's either A81SD Q503 or A81SC Q503. Cannot differentiate properly as the printing is fading.

Thanks.

[Wizard]

Re: Samsung 910t

That's not a IC. The samsung marking on the PCB by that 8 pin IC is ICxxx or Uxxx.

It is left of this blue VGA connector, 8 pin SMD. I expect to be 24Cxx on that 8 pin because this is near the 44pin microcontroller IC.

[Wizard]

Re: Samsung 910t

Yes this is serial EEPROM. IC201

full part number is KS24A81SC, I have to cross reference this to standard 24Cxx later.

Cheers, Wizard

[Bobdee]

Re: Samsung 910t

Yes this is serial EEPROM. IC201

full part number is KS24A81SC, I have to cross reference this to standard 24Cxx later.

Cheers, Wizard

I dug them out from under bed eventually, 2 monitors
SAMSUNG + SAMTRON (I am convinced the samtron is a samsung)

SAMSUNG..........model 710m s
.......................type No gh17ms
.......................model code gs17msss/edc
.......IC200
.......A81SC
........ C411
.............................................................................

SAMTRON............model 73v c
.........................type No gh17ls
.........................model code gs17vtss/edc
.......IC201
.......A81SC
........ Q501

Same as joshuashsong
Thanks

[Wizard]

Re: Samsung 910t

To both guys with (910T) 19" and 17" of this model, use 24C08. Find a junker board (any, don't have to be exact board, just the one that use 24C08 with this chip and try it. Otherwise try 24C16 instead. Just computer will not address all of it. This C08 is 1K byte while C16 is 2K, sufficient space for user settings.

Cheers, Wizard

[Kevin O'Henly]

Re: Samsung 910t

I am trying to repair a samsung 920N that also uses the MJ19BS smps/inverter.

Can that be handled here or should I open another subject?

The IP601 hybread may be at fault. How would I know for sure and where could a replacement be found.

Thankyou; you folks are the best!

rgs,
Kevin

[daiwapro]

Re: Samsung 910t

I replace KS24A81SC but still no display.

[sceva]

Re: Samsung 910t

Yes this is serial EEPROM. IC201

full part number is KS24A81SC, I have to cross reference this to standard 24Cxx later.

I have a 710t with same symptoms as original post, with the same board, and found a A81SC off another board. After swapping them out I get "Digital" showing on the screen and then "Analog", and then goes black. It is a little weird since the 710 does not have a digital input.

[voithian]

Re: Samsung 910t

Hello to everybody,

as you might notice, I'm not a native speaker of English (I'm German) and this is the first time that I participate in an English-speaking forum. So please bear with me, if something isn't expressed clearly or if I do something wrong.

But nevertheless, I have a problem with my Samsung 910T and any help would be greatly appreciated.

After switching on with the power button, the backlight comes on for about 100 or 200 milliseconds and you can perfectly see the Windows desktop. After that, the screen goes totally black and nothing can be seen anymore. The green power LED is continously on (not blinking).

If I switch the display off and then on again, the behavior is the same. No matter, if I use the digital or the analog or no input signal at all, it's all the same.

After searching this forum, I have already used my DMM to check the voltages on connector CN600 and I have found the following values:

PIN 1+2: +14V
PIN 3,4,5: 0V
PIN 6+7: +5V
PIN 8 (ADJ_BL): +2,94V
PIN 9 (BL_EN): 4,2V (when on, 0V when off)

I couldn't manages to replace the capacitors on the inverter board so far, since I have to buy or order them first. But at least, the 5V and 14V seem to be perfectly OK. Can a bad capacitor cause a malfunction of the backlight even when the 5V and 14V outputs are OK?

I don't know if the blank screen has to do with a missing supply voltage for the backlight, or, on the other hand, if there is sufficient voltage from the inverter but the screen is forced blank through pin ADJ_BL. In the latter case, replacement of the capacitors shouldn't be necessary. Or am I wrong?

So, now I have a few questions:
Is there a possibility to check the backlight supply voltage coming from the inverter? The DMM is a CAT III device (max. 1000V input voltage). Is the voltage from the inverter DC or AC? OK, I know that there is high voltage, but I have survived color TVs with 25kV...

Is it possible to check, if the supply voltage is OK, but the backlight is forced dark by an external signal (e.g. ADJ_BL) instead? As I understand, you can set the brightness of the backlight with ADJ_BL, right? What does +2,94V (see above) mean? Dark? Bright? Something in between?

Someone mentioned checking a fuse, but this shouldn't be the cause for the problem, since the backlight comes on for 100 milliseconds, when switching on.

It would be great, if someone could give me some hints what to check before I try to order the replacement capacitors.

Thanks in advance.
Wolfgang

[retiredcaps]

Re: Samsung 910t

I'm not a native speaker of English (I'm German) and this is the first time that I participate in an English-speaking forum.

Your written english and grammar is WAY BETTER than most people who were born in North America.

You can look at this thread to give you some ideas (2 seconds to black),

https://www.badcaps.net/forum/showthread.php?t=10419

but this more recent one where the little upside down card might be more relevant

https://www.badcaps.net/forum/showth...ht=samsung+zd1

Also, post clear focused pictures of all your boards (top down view - both sides) after reading

https://www.badcaps.net/forum/showthread.php?t=1868

[voithian]

Re: Samsung 910t

You can look at this thread to give you some ideas (2 seconds to black),
https://www.badcaps.net/forum/showthread.php?t=10419

Thank you for your quick response. I'll go into that thread and see if it helps to solve the problem.

but this more recent one where the little upside down card might be more relevant
https://www.badcaps.net/forum/showth...ht=samsung+zd1

I'm afraid this doesn't help. My board doesn't have this upside down card.

Also, post clear focused pictures of all your boards (top down view - both sides) after reading

I'll take some photos tomorrow morning (it's almost time to go to bed in Germany) and post them here.

[voithian]

Re: Samsung 910t

You can look at this thread to give you some ideas (2 seconds to black),
https://www.badcaps.net/forum/showthread.php?t=10419

I've read your troubleshooting guide, but unfortunately, I don't have spare CCFLs to check them one after the other.
And to be honest, I don't like the idea of desoldering components like diodes, transistors, capacitors, etc. and measure their values.
One additional problem is the fact that I have to know, which of the components is involved in generating the voltage for the backlight.
By the way, I haven't got any circuit diagrams for the power supply and inverter board on the internet. They are not in the service manual.

I wish someone could say: From my experience, with Samsung 910T and black screen after 100 milliseconds, the problem is normally caused
by that or that or that and you should first do that and then that and that to find out what is responsible for the malfunction.

Any further hints would be greatly appreciated.
Wolfgang

[PlainBill]

Re: Samsung 910t

I've read your troubleshooting guide, but unfortunately, I don't have spare CCFLs to check them one after the other.
And to be honest, I don't like the idea of desoldering components like diodes, transistors, capacitors, etc. and measure their values.
One additional problem is the fact that I have to know, which of the components is involved in generating the voltage for the backlight.
By the way, I haven't got any circuit diagrams for the power supply and inverter board on the internet. They are not in the service manual.

I wish someone could say: From my experience, with Samsung 910T and black screen after 100 milliseconds, the problem is normally caused
by that or that or that and you should first do that and then that and that to find out what is responsible for the malfunction.

Any further hints would be greatly appreciated.
Wolfgang

True story: Several decades ago my Mother came for a visit. When it came time to take her to catch her flight back I was having problems with my car. It was idling rough, lacked power, etc. Still, I was able to get Mom to the airport in time in spite of a constant stream of advice. My brother had a similar problem on his car and it turned out to be a cracked gasket on the intake manifold; Mom insisted this must be the problem with my car.

After seeing Mom off, I took a few minutes to examine th engine, then stopped off at an auto parts store, picked up the part I suspected, and replaced it. Problem solved. It was a cracked distributor cap.

The moral: Similar symptoms can have different causes. Blindly replacing parts because 'Tom fixed it with an intake manifold gasket' is useful only if the causes are the same.

There are several common faults with Samsung monitors. Bad capacitors are common. Their video processing chips are notorious for failing. And the inverter transformers are prone to shorts. In the case of this failure the prime suspect is one of the two inverter transformers.

However, that information is not absolute. One of the transformers could be open. Or you could have a bad CCFL. Capacitors whose ESR has risen have been known to trigger the shutdown. Defective (cracked, leaky) resistors, capacitors, and diodes on the return path can cause the problem. Since you refuse to troubleshoot the problem it will be necessary to use other means to fix this monitor.

Look at he picture of the back of the power supply / inverter board. About halfway down the left side is a mounting hole. Starting at that hole, draw a straight line across the board, and back around the top of the board. If the problem isn't the CCFLs or the power supply capacitors, the defective component is in the area 'below' the line. Good luck.

PlainBill

[retiredcaps]

Re: Samsung 910t

And to be honest, I don't like the idea of desoldering components like diodes, transistors, capacitors, etc. and measure their values.

In a future revision, I will write that all the tests are done in circuit (which is what I do).

And explain that IF the measurements look suspicious, you will have to remove the component to ensure the measurement is valid and not affected by the circuit design or nearby components.

[voithian]

Re: Samsung 910t

And the inverter transformers are prone to shorts. In the case of this failure the prime suspect is one of the two inverter transformers.
However, that information is not absolute. One of the transformers could be open.

OK, shouldn't be a problem to check. I'll unsolder the transformers and measure their values. Luckily, I have two them to compare...

Or you could have a bad CCFL.

Not easy to check. I don't have a spare CCFL. Can I unplug one of the 4 connectors and see if the backlight works with the remaining 3 CCFLs. Does anyone know if the OZ960 circuit detects that one CCFL is disconnected?

Capacitors whose ESR has risen have been known to trigger the shutdown. Defective (cracked, leaky) resistors, capacitors, and diodes on the return path can cause the problem. Since you refuse to troubleshoot the problem it will be necessary to use other means to fix this monitor.

Maybe this a misunderstanding. I am willing to troubleshoot the problem, but I think there is no sensible way to check 100 or even more capacitors, resistors, diodes, transistors and ICs in such a complex circuit like the inverter is. Almost all of the components are SMD and I can't easily unsolder one leg. Without a circuit diagram it is very difficult to determine if a value is correct or not. Furthermore, with SMDs it's often nearly impossible recognize the nominal value of a component because you can't read it.

Any suggestions how to proceed?

[PlainBill]

Re: Samsung 910t

OK, shouldn't be a problem to check. I'll unsolder the transformers and measure their values. Luckily, I have two them to compare...


Not easy to check. I don't have a spare CCFL. Can I unplug one of the 4 connectors and see if the backlight works with the remaining 3 CCFLs. Does anyone know if the OZ960 circuit detects that one CCFL is disconnected?

Maybe this a misunderstanding. I am willing to troubleshoot the problem, but I think there is no sensible way to check 100 or even more capacitors, resistors, diodes, transistors and ICs in such a complex circuit like the inverter is. Almost all of the components are SMD and I can't easily unsolder one leg. Without a circuit diagram it is very difficult to determine if a value is correct or not. Furthermore, with SMDs it's often nearly impossible recognize the nominal value of a component because you can't read it.

Any suggestions how to proceed?

Troubleshooting IS tedious, but is possible even without a circuit diagram. Removal of components is optional in most cases.

Disconnecting a lamp won't tell you much. The OZ960 controller shuts down if the output of any transformer exceeds a certain level. This is known as over voltage protection, or open lamp protection. Disconnecting three lamps and watching for a flash from the fourth will give a clue, but the flash may not be bright enough to see. A simple jumper will disable OVP, but if a lamp is open the high voltage may damage a transformer.

PlainBill