Samsung LED LCD UE32C5100 no power no stand-by

[R_J]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Have you replaced QM820? When the power ON/OFF is changed the voltage on point A changes, this should control the gate of QM820, I suspect QM820 is defective

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Thanks for the reply R__J.
I also think that the QM820 is defective just needed some confirmation.
Now the problem to find a spare around here... only a few shops that sell parts.
It is almost easier to get them online but the postage charges makes a 50c. part cost around 5$....
As soon i get the part i test and post back if it is working.

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Hello,
So after 4 months of waiting, I finally got the part i ordered (QM820).
I replaced it and now i have my PSU delivering all the voltages to the main board.... the bad news is the set is still dead... NO STAND-BY LED.... nothing.

Now i assume i may have a bad fuse on the main board caused by the failure of the QM820.
Any leads on where to start looking?
Since there is no stand-by LED, maybe if i go back in the circuit to where the LED supply should come from i find the issue.

Thanks!

[nomoresonys]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Now test the connector again with everything hooked up, see what voltages you have, number 3 below:

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Hello!
Thanks for the feedback.
I have checked all the voltages as you told me and everything is according to the voltages printed next to the connector.
So i started looking around in the main board, all the fuses where ok but i had no voltage supplying the ICs.
After searching i found out that my IC201 (9167A-33PB) was receiving the 5V supply but on the output i don't get the 3.3V that supply the logic ICs including the one that controls the stand-by LED.
When i measure the output pin my multi-meter sows zero and from time to time it gets up to 1V.

Is there a way to measure if i have a short on the 3.3V line? If i measure in Ohms between the GND and the 3.3V it shows open circuit. (----)

I don't have this part to replace have to order it... can i use something like resistors do go from 5v to 3.3V and safely see if the set starts?

Uploaded some pictures from the board and IC as well as the schematics page.

Thank you!

[dick_barton]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Pin 1 is at 5V and Pin 3 also needs to be connected to at 5V to operate. Output should be 3.3V If not then ......

Lift one end of BD215 and check the output voltage at pin 5

If there's no voltage then check C294 is not short circuit and if possible measure it's value.

Finally, replace IC201.

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

The technical doc from the (9167A-33PB) says that the voltage on pin 3 should be maximum 1.6V and not 5V. I have 5V on pin 1 and around 1.4v after the resistor for pin 3.
But i have no output on pin 5.

[dick_barton]

Re: Samsung LED LCD UE32C5100 no power no stand-by

The 1.6V refers to the minimum voltage required to enable the IC.

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Ok. Thanks for the info.
I just measured all the pins and it is like this:

Pin 1 - 5,2v
Pin 2 - 0v (gnd)
Pin 3 - 1,13v
Pin 4 - 0v
Pin 5 - 0,5v

Pin 4 should be high and between pin 3 and the 5v i only have a resistor with 4.7k

[Tdiamarelo]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Just got the set working. Replaced the 4.7k resistor whit one 4.7k across pin 1 and 3 removed the micro one plugged in and got stand by and the set started after power button push. Measured the micro resistor and got me 47k instead of 4.7k

Now the next issue solder a very thinly resistor whit and iron double size of it....
Thanks dick barton for your help!

[dick_barton]

Re: Samsung LED LCD UE32C5100 no power no stand-by

Glad you got there in the end. Good result.

[Fesmitronica]

Re: Samsung LED LCD UE32C5100 no power no stand-by

I have the same problem, the PSU already test and is ok.
have the voltages A5v1 , A3v3 , SA3v3 , SPI_EN , STB_EN also correct but
the standby led is off.
In the XTAL 24MHZ the measure is 700Hz
Anybody have the same problems and can resolved.
Thanks