Wharfedale LTF37K1CB Power Issue

[Atomical]

Hi,

I have a Wharfedale LTF37K1CB 37" LCD that has a power issue.... It wont turn on

The light is lit on the front of the unit and I have tested the power buttons ect and are fine. Remote is tested working too.

Ive opened her up and there are 4 boards on the back of the LCD panel.

I have taken pictures of the power board and main board..






I have checked for popped or bulging caps but cant see any. Anyone else had the same issue and can give me some pointers. I have a DMM and access to an ESR but cant get to that until next saturday as I am on a course during the week

Hopefully someone can show me some pointers or advice to get this thing going again..

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

I am getting 5v to the board so dont think its the power supply, Cant test 12v as I cant turn the set on..

Think it might be the main board thats goosed... Any pointers what to look for?

Its a MSD109CL V400 0091801398

[budm]

Re: Wharfedale LTF37K1CB Power Issue

OK, on the right hand side of the power supply board where the connectors with red and black wires are attached to, can you show closed up pictures of those connectors? There should be some voltage and pin function printed next to those connectors.
P/N of the power supply board, I can see the check box under the heat sink with some numbers next to it.

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue




The port to the left thats shadowed on the bottom picture is GND and +5V

[budm]

Re: Wharfedale LTF37K1CB Power Issue

The one with 4 pins seems to have the label 'ON/OFF' close to it but not sure if it is for the last pin of the 4-pin or the last pin of the connector to the right of the 4-pin connector. I cannot tell from the pictures.

[landyboy]

Re: Wharfedale LTF37K1CB Power Issue

Can you take a pic of the Capacitors from the side. The ones under the Heat sink. On the same end as the plugs you took the pictures of.

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

I will take pics of the sides when I get home later today, and thanks so far

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue





Heres some more pics as requested...

[budm]

Re: Wharfedale LTF37K1CB Power Issue

OK, I am trying to figure out the 4-pin connector (it has 3 wires atteched to it) on the power supply, where doe it go to? To the main board?

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

Yes. Ive colour coded and labeled everything I know.

The top connector on the main board has has gnd and 2 vcc (Purple mark).

[budm]

Re: Wharfedale LTF37K1CB Power Issue

OK, so on the main board, there are labels for those pins, can you post those labels?

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

On the main board....

From the pic labeled green..

[budm]

Re: Wharfedale LTF37K1CB Power Issue

OK, that's good. Set you meter to DC mode and, red probe on the 'PW-ON/OFF' pin when TV is off and when power switch is activated, black probe on the chassis and see what voltage you are getting.

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

I get 0.03 when the sets just plugged in and the same when I press the power button.

[budm]

Re: Wharfedale LTF37K1CB Power Issue

OK, that is why the main power supply is activated, only the standby power supply is working, the main board is not sending out the PWR-ON/OFF (PS_ON) to turn on the power supply. You will need to troubleshoot the main board next.

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

ok. What area do you suggest?

[budm]

Re: Wharfedale LTF37K1CB Power Issue

See the pictures of the regulators that need to be tested.
Please read this any report the results as retiredcaps format has indicates.
https://www.badcaps.net/forum/showth...999#post300999

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

Starting at the top right and working clockwise round.

)11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.14
pin 3 = 0.85


LD18 -> line 1 of the IC
Y437 -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.00
pin 3 = 0.14


L780SC2T -> line 1 of the IC
GK1BN VW -> line 2 of the IC
CHN 815 -> line 3 of the IC
pin 1 = 0.39
pin 2 = 0.00 Cut pin
pin 3 = 0.00


)11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.10
pin 3 = 0.85


AZ10845 -> line 1 of the IC
-3.3E1 -> line 2 of the IC
751K99 -> line 3 of the IC
pin 1 = 0.00
pin 2 = 3.30
pin 3 = 5.03


)11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 3.22
pin 3 = 5.03


)11 8CW -> line 1 of the IC
1117L -> line 2 of the IC
pin 1 = 0.70
pin 2 = 3.22
pin 3 = 5.03

[budm]

Re: Wharfedale LTF37K1CB Power Issue

3.3V regulator, right now the input voltage is too low for it to work
[B[/B])11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.14
pin 3 = 0.85

right now the input voltage is too low for it to work
LD18 -> line 1 of the IC
Y437 -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.00
pin 3 = 0.14

It is 7805 5v 780x series regulator, right now the input voltage is too low for it to work
L780SC2T -> line 1 of the IC
GK1BN VW -> line 2 of the IC
CHN 815 -> line 3 of the IC
pin 1 = 0.39
pin 2 = 0.00 Cut pin
pin 3 = 0.00

3.3v reg, right now the input voltage is too low for it to work
)11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 0.10
pin 3 = 0.85

3.3v reg, OK
AZ10845 -> line 1 of the IC
-3.3E1 -> line 2 of the IC
751K99 -> line 3 of the IC
pin 1 = 0.00
pin 2 = 3.30
pin 3 = 5.03

3.3v regulator, OK
)11 8CH -> line 1 of the IC
17-33L -> line 2 of the IC
pin 1 = 0.00
pin 2 = 3.22
pin 3 = 5.03

Variable regulator pin 1 voltage of 0.70V + 1.25V ref then the output should be 1.95v but you are getting 3.22V, so it is bad. Variable regulator pin 1 voltage of 0.70V + 1.25V ref then the output should be 1.95v but you are getting 3.22V, so it is bad. The voltage between pin 1 and pin 2 should always be 1.25V for 1117 series variable regulator.
)11 8CW -> line 1 of the IC
1117L -> line 2 of the IC
pin 1 = 0.70
pin 2 = 3.22
pin 3 = 5.03

[Atomical]

Re: Wharfedale LTF37K1CB Power Issue

Righty. I will get a new 1117 variable regulator tomorrow and swap the bottom bad one then check voltages again in all the other regulators.