Samsung UN46C6400RFXZA audio but no picture (pics incl).

[GLInick]

It turns on, and the welcome chime plays. The LEDs light up, there is a glow on the screen, but no picture is shown.

There is a ticking sound from a large component on the power board that is a coil of some type (easier to see on the back side). It has a white plastic cover with markings -- see pics.

Power board:
I inspected all electrolytic caps and none looks obviously burnt.
I measured the voltages at connector CNL801 (goes to the LEDs, and according to the chart on the PCB they are LED1 +/- and LED2 +/-, with some pins marked N.C). The voltage fluctuates quite a lot between 2v-7v (I could be off, it changes quite fast)
I measured voltages at connector CNM801 (goes to main board), and based on the chart printed on the PCB, here is what I measured (all voltages wrt ground, i.e., black lead to chassis):
PIN#-Measured Indicated_on_chart
----------------------------------
Pin1-12.6 12V
Pin2- N.C
Pin3-12.6 12V
Pin4- 4.83 BL_ON
Pin5-12.6 12V
Pin6-0.47 P_DIM
Pin7- GND
Pin8-0.30 H_SYNC
Pin10- GND
Pin11-5.2 5.3V
Pin12- GND
Pin13-5.2 5.3V
Pin14-5.2 5.3V
Pin15-17.24 Vamp
Pin16-5.21 STBY
Pin17-17.27 Vamp
Pin18-1.53 PS_ON

Main board (HDMI and antenna inputs, ethernet port):
On the main board, there are a lot of test points on the underside, but I don't know what to test for.

T-CON board:
I tested both sides of the T-CON board fuse (white, with gold tips, and it measures 12.46 Volts

I am hoping the buzzing sound of the component on the power board is an indication that the fault is there.

Pics are here: https://photos.app.goo.gl/nfR6V7KXUCJWHT3K9

Any pointers would be really appreciated.

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Please upload good clear pictures here.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I wasn't able to see the full-featured editor with the "manage attachments" feature when I posted originally.

- Power supply board
- Main board
- TCON
- component on power supply board that makes ticking noise.

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Samsung BN44-00356A power supply/LED driver board.
That is power transformer for the LED driver and for 12V, Vamp, and switched 5V.
Try having the ribbon cable between the T-con and the LCD panel connected one at a time to see what you get on the screen.
What is the history of the TV?

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

History: we don't use it very much but it stopped working one day.

What do those ribbon cables from the TCON to the panel map to, horizontal/vertical or left/right? Curious to know what I should expect to see if one or the other gets disconnected.

also, on that power transformer, is the ticking normal? Any voltage tests I can do?

Should I have any inputs connected? I don't currently, I just try to bring up the system menu.

P.s. can you point me to the moderator please. I'd like to edit the OP for better formatting now that I have full wysiwyg.

[nomoresonys]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

" Curious to know what I should expect to see if one or the other gets disconnected": You should see a good picture on half the screen if working correctly.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I don't get picture on either half when I unplug each of the two T-CON cables on the bottom.

The backlight/glow will become brighter as I cycle through the input sources (but it is unclear what the current input source is).

What is next, anything else to try?

[budwich]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I think that a "picture outcome" is the "optimum"... you are likely looking for a change. Lots of sets display a white screen for the disconnected side. You have checked voltages at the PS but there are also voltage points labeled on the tcon that may help.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I'll check the test points on the T-CON then. Is there some writeup on it somewhere?

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I am pasting the voltage measurements I posted originally for the Power Supply, formatted for easy reference.

Voltages at connector CNM801 (goes to main board, all voltages wrt ground, i.e., black lead to chassis):

[U]PIN#	Measured	Indication on PCB chart[/U]
Pin1	12.6		12V
Pin2			N.C
Pin3	12.6		12V
Pin4	 4.83		BL_ON
Pin5	12.6		12V
Pin6	0.47		P_DIM
Pin7			GND
Pin8	0.30		H_SYNC
Pin10			GND
Pin11	5.2		5.3V
Pin12			GND
Pin13	5.2		5.3V
Pin14	5.2		5.3V
Pin15	17.24		Vamp
Pin16	5.21		STBY
Pin17	17.27		Vamp
Pin18	1.53		PS_ON

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

The T-CON board, both sides.

Any pointers to where to check voltages would be appreciated.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Also, I noticed there is a schematic posted by budm. Is this applicable to the T-CON I have?

See:
https://www.badcaps.net/forum/showpo...&postcount=401

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Start checking Voltage at the test points, I can see:
VCC12
VCC33
AVDD
VCOMxxx
VOFFE
.......

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I am attaching an updated image of the T-CON board with a grid for easy reference.

Here are the values I have measured with TV on, and no input sources.

Please let me know what other values I will need to check.

A big thank you for all this help. I'd lie to save this from becoming e-waste.

[B][U]LOC	TEST_POINT	MEASURED (to chassis, in DC VOLTS)[/U][/B]
		
[B]CON1 connector	[/B]	
J14	VIN		12.65
J14	GND

[B]RIGHT of CON1 connector[/B]		
J18	AVDD		0.5-0.9
		
E16	VCC12		1.21
F15	VCC33		3.25 - 3.27
H22	VOFFE		-2.x - 1.x
		
F19	VSS		-2.x - 0.x
E20	VONE		0
		
[B]LEFT of CON1 connector[/B]		
L3	VR		0
K9	SDA		0.33 - 1.46
K9	SCL		1.6 - 3.10
K8	WP		3.26
JK6	SDA_EXT		3.26
JK6	SCL_EXT		3.26
J7	SDA_I		3.26
I7	SLC_I		3.26
		
[B]LEFT OF MAIN CHIP	[/B]	
G7	RST		0.5 - 3.25
G8	B_INT		0
F9	SYNC_OSCB	0.17
E6	STV0		0
E8	DEO		0.46 - 2.75
D8	T_RDY		0.00 - 0.12
D7	CPV1		0
D7	CPV2		0
D7	CPV3		0
D6	STV		0

[B]RIGHT OF MAIN CHIP	[/B]	
F13	KB		0.27 - 1.75
F13	HSYNC_0		0.00 - 0.07
F13	VSYNC_0		0.00 - 0.06
F13	S_STT		0
F13	S_DATA		0
F13	S_CLK0		0
G13	SYNC_DEO	0
		
[B]FPC_LEFT connector	[/B]	
C8	VDDMHL_1	0.04 - 0.10
C8	VCOMS2		0.06 - 0.25
C7	VCOMS1		0.06 - 0.25
C7.9	F_VCOML		0.07 - 0.26
C7.25	AP_SYNC		0.03 - 1.2x

C4	VCOMG1		0.08 - 0.26
C4	VCOMG2L		0.06 - 0.25
		
[B]FPC_RIGHT connector	[/B]	
C21	VDOMHL_2	0.05 - 0.10
C21	VCOMG3		0.06 - 0.26
C21	VCOMG2R		0.05 - 0.25
C20	VST2		0.05 - 0.25

C16	VCOMS3		-0.07 - 0.25
C16	VCOMS4		-0.05 - 0.25

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

It looks like ICD1 is not running. P/N of that IC? I can see MX17?????
Try not having both ribbon cables between the T-CON and the LCD panel disconnected and see if the AVDD will be present or not, if not then check the resistance between AVDD test point and GND to see what kind of resistance you have.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Here is the image without the grid lines.

ICD1 is
MAXIM
MAX17122
ETL 013
ITXBZB0

I will follow up with the measurements and tests shortly.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

Try not having both ribbon cables between the T-CON and the LCD panel disconnected

Just to be clear, all of the measurements I posted above were taken with everything connected, so both of the ribbon cables from the LCD were in circuit.

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

So try disconnecting the two cables between T-CON and the panel to see what you will get on AVDD.

[GLInick]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

I get the following results regardless of whether any or both ribbon cables are connected:

• voltage fluctuates between 0.5 - 1.02 V

• resistance between AVDD and ground is about 7.9x KOhm

[budm]

Re: Samsung UN46C6400RFXZA audio but no picture (pics incl).

AVDD should be around 15 ~ 20VDC so there is malfunction in that section of the ICD1.
See the application circuit of the IC.
MAX17122: https://www.maximintegrated.com/en/p.../MAX17122.html