Samsung UE22ES5000 Led tv no standby

[datalore44]

Hi, I have limited knowledge of electronics and have no access to an oscilloscope. I am trying to fix my samsung tv, and would really appreciate any help I can get.
So the board I am having trouble with is the BN44-00505B Power board. I have between 1.8 to 2.3 volts at the 5v reference points. I have detected and changed a faulty diode (DM861). I have also replaced any bad capacitors and the IC (ice3br1065jf). I am getting 330v from the rectifier. The output header pins are as follows:
1-B13v
2-EPWM
3-B13v
4-NC
5-VAMP
6-B-ON
7-VAMP
8-GND
9-GND
10-GND
11-B5V
12-A5V 1.8 TO 2.3
13-B5V
14-P-ON

I am not getting any voltages from the pins except pin 12
The chip on the back is a MAP3204C which I think is a LED driver.
Any help would be very much appreciated.
Alan.

[nomoresonys]

Re: Samsung UE22ES5000 Led tv no standby

Wonder if you need RM859 resistor in place, did you have this tv working or did you receive it not working? you know history?

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Hi. This is my tv. It was working fine then just died.

[budm]

Re: Samsung UE22ES5000 Led tv no standby

"12-A5V 1.8 TO 2.3"
If you run the power supply board by itself and not connected to anything else, is A5V stable @5V?

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

No, it is exactly the same.

[nomoresonys]

Re: Samsung UE22ES5000 Led tv no standby

Check your diodes, go ahead and check m in circuit, if any don't check right, take it out of circiut and recheck it. https://www.youtube.com/watch?v=BXOS5czCb3Q

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Already checked all diodes and replaced 1 faulty one. Also checked and changed any faulty caps.

[nomoresonys]

Re: Samsung UE22ES5000 Led tv no standby

Oops my bad, I see you did it in first post. Did you check your mosfets?

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

I have checked the 3 mosfets on back of the board. I am confused by the small 3 pin packages marked ZDM, Q and QQ.

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Anyone else have any ideas? Also I cannot find a circuit diagram anywhere. Does anyone know where else I could find one please.

[R_J]

Re: Samsung UE22ES5000 Led tv no standby

Did you replace CM808 capacitor?
What number diode did you use to replace DM861?
Check that QM861 is not shorted

Also what is the voltage measured at the cathode of DM861

[budm]

Re: Samsung UE22ES5000 Led tv no standby

What dc Voltage do you get if you measure between cold side circuit ground and the Cathode of DM861, 852, 881?

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Did you replace CM808 capacitor?
What number diode did you use to replace DM861?
Check that QM861 is not shorted

Also what is the voltage measured at the cathode of DM861

Checked CM808 showing 50uf esr 0.14ohm vloss 0.8% I assume that is within tolerances.
The diode DM861 was a direct replacement SR320
There is no short at QM861 (seems to test ok)

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

What dc Voltage do you get if you measure between cold side circuit ground and the Cathode of DM861, 852, 881?

DM861 5.4 to 6v
DM852 1.6 to 2.3v
DM881 9.1 to 9.4v

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

Thank you all very much for your help.
There seems to be a lot of unstable voltages changes going on.

[R_J]

Re: Samsung UE22ES5000 Led tv no standby

If you remove one end of dm861, does your A5V come up? Was the original DM861 shorted (both directions)

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

If you remove one end of dm861, does your A5V come up? Was the original DM861 shorted (both directions)

Hi. If I remove the cathode end of the diode there is no voltage at the diode to ground. There is 1.18v on the pcb track where the diode connects and cold ground. The old diode was shorted in both directions.

[R_J]

Re: Samsung UE22ES5000 Led tv no standby

The voltage I wanted you to check with DM861 removed was the A5V (cathode of DM852) By removing DM861, that will eliminate anything after that diode, so the A5v should come up. If it does'nt there could also be a high load on one of the other secondary lines or the primary side is not operating properly.
have you checked RM803, DM802, ZDM803 & ZDM802? Also check JP831 0Ω near the cnm803 plug

[datalore44]

Re: Samsung UE22ES5000 Led tv no standby

The voltage I wanted you to check with DM861 removed was the A5V (cathode of DM852) By removing DM861, that will eliminate anything after that diode, so the A5v should come up. If it does'nt there could also be a high load on one of the other secondary lines or the primary side is not operating properly.
have you checked RM803, DM802, ZDM803 & ZDM802? Also check JP831 0Ω near the cnm803 plug

So checked the voltage with diode removed and it is stable at 5.22v.
0 ohm across the resistor jp831
all components seemed to check out ok. I assume ZDM803 and 802 are a zener diode?
Thank you for taking the time with this.

[R_J]

Re: Samsung UE22ES5000 Led tv no standby

Those zeners are likely ok, if the A5V standby is working with DM861 removed, then I suspect there is something loading the circuit After the DM861.
What is the resistance measured across CM864 and CM867?