T-con Samsung identifying problem

[wilson_campbell]

Have a samsung 320AB02CP2LV0.3 t-con that is not working. Ordered up a second hand one but it was faulty also. Trying to compare the voltage points from both to see if I can salvage/make one work.

T-con original (fuse used to blow due to power board issue, now fixed): Only shows vertical coloured strips now.

Power at f1: 9v
c1: 3v
c2: 8.6v
L2: 3v
L1: 9v
SD2: 3,0
SD1: 9,9
QDI: 2.6, 1.2, 3.3
CIN1 - CIN4 : 9v

Bad recieved T-con (worked for about 2 minutes before compete loss of picture)

Power at f1: 11v
c1: 3v
c2: 1-2v
L2: 3v
L1: 1-2v
SD2: 3,0
SD1: 0-2,0-1.9
QDI: 2.6, 1.2, 3.3
CIN1 - CIN4 : 11v

On the second hand one seems to be more bad voltage areas that vary in voltage ranges.

Original seems to be more consistent but only pulling 9v into the board.

Anyone got any ideas

[diif]

Re: T-con Samsung identifying problem

Is the 11v at f1 both sides ?

[wilson_campbell]

Re: T-con Samsung identifying problem

Yes on the new board it is 11v on each side. On the original it is 9v on each side.

[wilson_campbell]

Re: T-con Samsung identifying problem

Is the 11v at f1 both sides ?

Yes on the new board it is 11v on each side. On the original it is 9v on each side.

[fzabkar]

Re: T-con Samsung identifying problem

Can you tell us the markings on QDI, ICD2, ICD1?

SD1, L1 and ICD1 appear to constitute a boost converter. Therefore I would expect a much higher voltage at the AVDD test point (cathode of SD1).

ICD2 appears to be switching Vin, or perhaps it's an LDO regulator.

There appears to be a +3.3V test point to the right of L2, so that would suggest that L2 and SD2 constitute the Vio supply for ICT1 and its peripheral chips.

There is a 1.2V test point to the right of QDI, so that would suggest that QDI is the pass transistor for the Vcore supply for ICT1.

[wilson_campbell]

Re: T-con Samsung identifying problem

Can you tell us the markings on QDI, ICD2, ICD1?

SD1, L1 and ICD1 appear to constitute a boost converter. Therefore I would expect a much higher voltage at the AVDD test point (cathode of SD1).

ICD2 appears to be switching Vin, or perhaps it's an LDO regulator.

There appears to be a +3.3V test point to the right of L2, so that would suggest that L2 and SD2 constitute the Vio supply for ICT1 and its peripheral chips.

There is a 1.2V test point to the right of QDI, so that would suggest that QDI is the pass transistor for the Vcore supply for ICT1.

ICD1: TPS 65167A TI 88W Z916G4
ICD1: 442\
QDI: k A1718 Y 848

For both boards the 1.2v and 3.3v measurements match OK.

[fzabkar]

Re: T-con Samsung identifying problem

Fig 34, page 33 of the following datasheet (for ICD1) appears to have an application circuit that is similar to your own.

TPS65167A, Texas Instruments, Compact LCD Bias Supply for TFT-LCD TV Panels:
https://cdn.badcaps-static.com/pdfs/...6c316493a3.pdf

There should be a voltage of around 15V at the AVDD test point at the cathode of SD1.

I can see VOFF and VSS test points above L2 on your board.

ICD1 also has VGL (-8V) and VGH (+24V) outputs (according to the datasheet).

QD1 is a 2SA1718 PNP transistor for the Vcore supply (+1.2V).

2SA1718, PNP, -100V, -5A, Darlington:



I can't make sense of the part marking on ICD2.

There are also VON and VOFF test points at the bottom left corner of the T-Con PCB.

[Ltank]

Re: T-con Samsung identifying problem

I thought if the Tcon fuse was blown there was a problem withe the Pannel? Surges don't affect the Tcon it''s almost always the Power Supply or Main Board. Is the Pannel loading the Power to the Tcon and lowering the voltage?

[fzabkar]

Re: T-con Samsung identifying problem

ISTM that the panel may be loading the AVDD supply.

The T-Con PCB with the higher input voltage (11V) appears to have a failed AVDD regulator whereas the T-Con that is loading the input appears to have a working AVDD supply. Assuming that the AVDD rail powers the panel, this would point to the AVDD rail and/or the panel as the culprit.

I would measure the resistance between AVDD and ground, with and without the panel connected.

[wilson_campbell]

Re: T-con Samsung identifying problem

I thought if the Tcon fuse was blown there was a problem withe the Pannel? Surges don't affect the Tcon it''s almost always the Power Supply or Main Board. Is the Pannel loading the Power to the Tcon and lowering the voltage?

Hi

The original problem was with a shorted PNP transistor on the power board. The glue on it was causing it to short and then blow the T-conn fuse f1. See thread: https://www.badcaps.net/forum/showthread.php?t=48472

[wilson_campbell]

Re: T-con Samsung identifying problem

ISTM that the panel may be loading the AVDD supply.

The T-Con PCB with the higher input voltage (11V) appears to have a failed AVDD regulator whereas the T-Con that is loading the input appears to have a working AVDD supply. Assuming that the AVDD rail powers the panel, this would point to the AVDD rail and/or the panel as the culprit.

I would measure the resistance between AVDD and ground, with and without the panel connected.

will measure it tonight when I get back + other test points

[wilson_campbell]

Re: T-con Samsung identifying problem

ISTM that the panel may be loading the AVDD supply.

The T-Con PCB with the higher input voltage (11V) appears to have a failed AVDD regulator whereas the T-Con that is loading the input appears to have a working AVDD supply. Assuming that the AVDD rail powers the panel, this would point to the AVDD rail and/or the panel as the culprit.

I would measure the resistance between AVDD and ground, with and without the panel connected.

Original board readings:
Resist with panel cable connected: 4.65 Resist without panel cable: 7.5
AVDO: 9v
VOFF: -7.5
VSS: -7.5
VON: 7.7
VOFF: 0.7
VDD: 3.3

Second hand board:
Original board readings:
Resist with panel cable connected: 4.69 Resist without panel cable: 7.6
AVDO: moving from 0.5 to 1.9
VOFF: moving from -0.2 to -2.14
VSS: moving from -0.2 to -2.14
VON: moving from 0.17 to 3.0
VOFF: moving from -2.5 to +0.4
VDD: 3.3

I am assuming I did the resistance check correctly. Black to frame for ground, red to AVDD test point. Resistance setting on multimeter set to 20K to get a reading.

[wilson_campbell]

Re: T-con Samsung identifying problem

ISTM that the panel may be loading the AVDD supply.

The T-Con PCB with the higher input voltage (11V) appears to have a failed AVDD regulator whereas the T-Con that is loading the input appears to have a working AVDD supply. Assuming that the AVDD rail powers the panel, this would point to the AVDD rail and/or the panel as the culprit.

I would measure the resistance between AVDD and ground, with and without the panel connected.

Any ideas about the readings

[fzabkar]

Re: T-con Samsung identifying problem

Sorry, I'm stumped.

ISTM that 11V is an odd input voltage. I have little experience with flat panel TVs, but AFAICT 12V is the nominal supply voltage for most sets. Are you sure that your PSU has been correctly repaired?

AIUI, your static load resistances on the AVDD supply are 4.6K with the panel connected and 7.5K with the panel disconnected. Obviously the panel must be presenting a much lower resistance when it is powered up, so these readings are inconclusive. Assuming it is safe to run the set with the panel disconnected, I would see how the voltages behave when the set is powered up without the panel.

Your second set of readings are a little confusing. You now measure 9V at AVDD, yet in your first post you measured 9V at F1 and 9.9V at SD1. Note that you should get different voltages on either side of SD1. It is not clear where you are measuring these voltages. Also, if the booster is working, then the voltage at AVDD should be a lot higher than the voltage at F1.

The readings for the "second hand board" are also confusing. If AVDD is sitting at 0.5V - 1.9V, then this would suggest that SD1 is shorted or leaky.

[budm]

Re: T-con Samsung identifying problem

What is the LCD panel model number?

[wilson_campbell]

Re: T-con Samsung identifying problem

What is the LCD panel model number?

Hi,

The tv is an LE32A457C1D

[vinceroger69]

Re: T-con Samsung identifying problem

budm i think means what is the actual number of the lcd panel used in the set this is usually on a white sticker on the metal chassis on the back of the tv.

[wilson_campbell]

Re: T-con Samsung identifying problem

Sorry, I'm stumped.

ISTM that 11V is an odd input voltage. I have little experience with flat panel TVs, but AFAICT 12V is the nominal supply voltage for most sets. Are you sure that your PSU has been correctly repaired?

AIUI, your static load resistances on the AVDD supply are 4.6K with the panel connected and 7.5K with the panel disconnected. Obviously the panel must be presenting a much lower resistance when it is powered up, so these readings are inconclusive. Assuming it is safe to run the set with the panel disconnected, I would see how the voltages behave when the set is powered up without the panel.

Your second set of readings are a little confusing. You now measure 9V at AVDD, yet in your first post you measured 9V at F1 and 9.9V at SD1. Note that you should get different voltages on either side of SD1. It is not clear where you are measuring these voltages. Also, if the booster is working, then the voltage at AVDD should be a lot higher than the voltage at F1.

The readings for the "second hand board" are also confusing. If AVDD is sitting at 0.5V - 1.9V, then this would suggest that SD1 is shorted or leaky.

If I remove the fuse at f1 the voltage measurement coming into the the unit is 12v. Once the fuse is in place it then drops. I am therefore assuming that the voltage being delivered to the t-con is correct but the t-cons are then somehow effecting it and not drawing the same power down from the PSU. Also for the second hand t-conn board it did work for about 2 minutes and then I am assuming when it started to heat up a component failed (failed soak test).

I will try the voltage readings without the panel and post them to see if it helps

[wilson_campbell]

Re: T-con Samsung identifying problem

budm i think means what is the actual number of the lcd panel used in the set this is usually on a white sticker on the metal chassis on the back of the tv.

thanks for tip:

only other number I see is the model code:

LE32A457C1DXXU

[vinceroger69]

Re: T-con Samsung identifying problem

no neither of them are it basically if we can find what the lcd panel is we can look what voltages etc the tcon needs hence budm asking for it