Samsung 910t

[IRShifty]

Re: Samsung 910t

Can we have detail again?

What capacitors are used to replace and did this PSU get complete do-over with electrolytic capacitors? Little ones too.

Cheers, Wizard

Capacitors haven't been changed at all, replacements are in the mail.

Also: Can I use bipolar capacitors instead of general purpose ones?

[EGuevarae]

Re: Samsung 910t

Capacitors haven't been changed at all, replacements are in the mail.

Also: Can I use bipolar capacitors instead of general purpose ones?

You can not use GP caps on this kind of application (I mean, you can, but you should not). As for bipolar, I don't know.
Post something like this also : with (-) probe of DMM on pin 5 (either way, it is GND from top to bottom or bottom to top, is the middle one )
1.-
2.-
3.-
4.-
--
6.-
7.-
8.-
9.-

Tha would help.

[PlainBill]

Re: Samsung 910t

Capacitors haven't been changed at all, replacements are in the mail.

Also: Can I use bipolar capacitors instead of general purpose ones?

There are several reasons for not using bipolar caps. They would be larger, more expensive, less likely to be available in low esr ratings, etc, etc. I won't go into the implications of having a schizophrenic power supply, a monitor with manic - depressive tendencies, or the other bad jokes possible.

PlainBill

[IRShifty]

Re: Samsung 910t

12v
12v
gnd
gnd
gnd
5v
5v
0v
-100v

[PlainBill]

Re: Samsung 910t

12v
12v
gnd
gnd
gnd
5v
5v
0v
-100v

Something is wrong here!! Operator error?

PlainBill

[IRShifty]

Re: Samsung 910t

That is what i was confused on. Checking the voltage the same as i did the rest of the pins, This one went negative and kept changing to different readings all around -100. I am confused as well.

[kikkoman]

Re: Samsung 910t

service manual:



just opening didn't work for me, you have to 'save as...'

[EGuevarae]

Re: Samsung 910t

12v
12v
gnd
gnd
gnd
5v
5v
0v
-100v

That pin, in my case, is/was the BLON signal. It has voltage only when connected to a VBoard and with valid signal. The pin before it (the one you put 0v) was varying, so I guess it is/was the dimmer.
The PSU was connected to the VBoard or not?

[IRShifty]

Re: Samsung 910t

No it was not, i can get new voltages with the vboard in a little bit.

[EGuevarae]

Re: Samsung 910t

See page 9-1 (page 45) on the mentioned service manual. There's the connector pinout with the voltages that are/must be present.

[IRShifty]

Re: Samsung 910t

[IRShifty]

Re: Samsung 910t

With the vboard i am getting:

12V
12V
gnd
gnd
gnd
5V
5V
47mV
8mV

[kikkoman]

Re: Samsung 910t

pin 9 (BL_EN) should read 5V if switched on... but hey, it doesn't matter at all since your backlight works anyway.

pin 1 and 2 should be more like 13 or 14V according to the manual but i doubt that's the issue.

have you checked with both analog and DVI inputs?
if you have a scope, you could follow the manual (no input signal).

[Wizard]

Re: Samsung 910t

Dimming voltage (adj_BL) should be around 2.5 to 3.xV, The BL_EN is backlight enable pin which should go up to appox 2.5V ~ 5V (positive). I'm sure.

Cheers, Wizard

[EGuevarae]

Re: Samsung 910t

With the vboard i am getting:

12V
12V
gnd
gnd
gnd
5V
5V
47mV
8mV

The manuals says 14v,, however I too measured 12v on that pins.
The last pin, the BL_ON line, showed 5v with valid signal attached.

That goes on for about 10 sec and then it goes black and then the screen is populated with colored vertical lines

I've seen a similar behavior, but the screen ended completely white. That was caused by a short that left the BLON signal always on. If you turned off that unit, it would do that.
If you connect valid signal to it, it must display something. The unit I had that used to shut down itself after a valid signal was applied, was fixed by changing only one cap, the (1) in my crappy schematic/drawing, as per PCBONEZ instructions.

Measure the BLON line with valid signal attached.

[IRShifty]

Re: Samsung 910t

With a valid analog signal attached but the back lights detached, I receive 3.7V from the BL_ON pin. Once the monitor stops searching for signal the power LED is still green and the voltage drops to 8mV. A few seconds later the monitor is still on but the power LED goes out.

[EGuevarae]

Re: Samsung 910t

With a valid analog signal attached but the back lights detached, I receive 3.7V from the BL_ON pin. Once the monitor stops searching for signal the power LED is still green and the voltage drops to 8mV. A few seconds later the monitor is still on but the power LED goes out.

Someone on a VP201b thread took a video of teh unit's behavior and uploaded it to youtube and posted the link. Can you connect all together, apply valid VGA signal and do teh same? I'm really confused.... (both with signal and without signal applied if possible) ...I ran out of suggestions.

[joshuashsong]

Re: Samsung 910t

My Samsung 910T with MJ19BS IP Board is having the following problem:
Once power on, the monitor will show a small screen on the upper left corner showing "Digital/Analog", after a while, it will display "check signal cable" - analog / digital depending on the source selected. If the VGA 15pins or DVI-D cable is connected, the monitor will goes drak & blank, & switch to sleep mode. When press the "Menu" button, it will show "Test Good".

I have follow your suggestion & measure the voltages on the CN600 when the signal cable is not connected. The screen show "Check signal cable"

Pin 1 - 12.3V wrt to pin 5
Pin 2 - 12.3V wrt to pin 5
pin 3 - 0V
pin 4 - 0V
pin 5
pin 6 - 5.02V
pin 7 - 5.02V
pin 8 - 50mV
pin 9 - 3.36V

If the signal cable is connected & the monitor goes into sleep mode, CN600 voltages are:

Pin 1 - 12.3V wrt to pin 5
Pin 2 - 12.3V wrt to pin 5
pin 3 - 0V
pin 4 - 0V
pin 5
pin 6 - 5.02V
pin 7 - 5.02V
pin 8 - 50mV
pin 9 - 0V

I have tried replacing the 470uF 25V capacitor on the IP board as per your previous response, the problem still remained unchanged. Please help.

[EGuevarae]

Re: Samsung 910t

My Samsung 910T with MJ19BS IP Board is having the following problem:
Once power on, the monitor will show a small screen on the upper left corner showing "Digital/Analog", after a while, it will display "check signal cable" - analog / digital depending on the source selected. If the VGA 15pins or DVI-D cable is connected, the monitor will goes drak & blank, & switch to sleep mode. When press the "Menu" button, it will show "Test Good".

I have follow your suggestion & measure the voltages on the CN600 when the signal cable is not connected. The screen show "Check signal cable"

Pin 1 - 12.3V wrt to pin 5
Pin 2 - 12.3V wrt to pin 5
pin 3 - 0V
pin 4 - 0V
pin 5
pin 6 - 5.02V
pin 7 - 5.02V
pin 8 - 50mV
pin 9 - 3.36V

If the signal cable is connected & the monitor goes into sleep mode, CN600 voltages are:

Pin 1 - 12.3V wrt to pin 5
Pin 2 - 12.3V wrt to pin 5
pin 3 - 0V
pin 4 - 0V
pin 5
pin 6 - 5.02V
pin 7 - 5.02V
pin 8 - 50mV
pin 9 - 0V

I have tried replacing the 470uF 25V capacitor on the IP board as per your previous response, the problem still remained unchanged. Please help.

Post pics and cap info.

[lucky13]

Re: Samsung 910t

If you can see the message box, then your backlights are working and the problem is likely not the power+inverter board. The problem would likely be the main/signal board (where your VGA connects to). There maybe a couple of voltage regulator ICs on it dying... post some pix of it here.