Insignia NS-24E730 LCD tv no power

[suiramix]

Hi there,
This forum is an excellent place to start exploring and learning …
After reading and more reading I decided to go ahead and ask for your help:
So I tried to troubleshoot a (like-new) 24 inch LED-LCD Insignia tv with power problems: plug-in, the standby indicator was blinking red and stay red and sometimes goes off when try to power on.
Open the cabinet and inspected the power supply board and capacitors for bulging or leaking, nothing suspicious, measured voltage as follow:
BON=0V, PWM=0V, STB=5V, 5V-1=0V, PON=0V, 7V=0V, 12V=12.4V so the output voltage looks ok.
Did reset it (unplug for more than 10min, press and hold power button from tv for 1 min and plug-in again) and surprising the tv power up and ask for initial set-up.
But after few minutes, no standby indicator light, completely dead unit…try to reset, same results.
Open again, plug-in and re-measured the voltages:
BON=0V, PWM=0V, STB=5V, 5V-1=5V, PON=5V, 7V=0V, 12V= 12.4V so looks like something is on, but no standby indicator red/blue, no image or sound. Checked for jammed side buttons - nothing wrong.
Disconnected the mainboard from the power supply and measured again I got same voltage reading like first time: STB=5V, 12V= 12.4V (other outputs 0V).
At this point I am lost and your help will be appreciated.
Thanks!

[retiredcaps]

Re: Insignia NS-24E730 LCD tv no power

Did reset it (unplug for more than 10min, press and hold power button from tv for 1 min and plug-in again) and surprising the tv power up and ask for initial set-up.
But after few minutes, no standby indicator light, completely dead unit…try to reset, same results.

1) Post clear focused top down pictures of all your boards following my sig file below exactly. We want the picture compositions like so

https://www.badcaps.net/forum/showpo...94&postcount=1

2) Try pointing a fan to the back of the TV to see if the TV stays on longer. If it does, you could have a bad solder joint or some component is dying after too much heat.

[suiramix]

Re: Insignia NS-24E730 LCD tv no power

Hi retired,
Please find the attached photos.
At this point I am not able to power on the TV, so no standby light, just the voltage mention earlier (with and without main board connected)!

[retiredcaps]

Re: Insignia NS-24E730 LCD tv no power

Hookup everything.

The main board controls whether the TV comes or not. It usually needs steady and stable 5V DC voltage in order to work. One or more of the voltage regulators on the main board can be bad?

To test a voltage regulator (circled in red),

1) Set your multimeter (if manual range) to 20V DC.

2) Put your black probe on a ground screw (circled in black). Leave it there the entire time. This is your ground.

3) Put your red probe on each of the pins including the "cut" pin, but ignore the "fat" tab. The fat tab is "up" or "north". Number the pins left to right.

4) You should have 3 readings per regulator.

5) Report them like so along with the part number of the IC.

U100
AS1117-33
pin 1 = 0.0
pin 2 = 3.3
pin 3 = 5.0

edit: Manage attachments failing for some reason in both Opera and Chrome browsers, but the ones I can read are N602, N60, and N607.

[suiramix]

Re: Insignia NS-24E730 LCD tv no power

I just add the photo with regulators location and those are the voltage reading:

N603, AZ1117D
Pin 1= 0
Pin 2= 3.3
Pin 3= 5

N607, 1117
Pin 1= 1.3
Pin 2= 2.5
Pin 3= 5

N602, 1117
Pin 1= 2
Pin 2= 3.3
Pin 3= 5

N606, 1117
Pin 1= 0.6
Pin 2= 1.8
Pin 3= 3.3

N608, 1117
Pin 1= 3.8
Pin 2= 5
Pin 3= 8.8

N604 -MP1482-buck regulator for main IC pin 3 output 1.8V
N605 -MP1482-buck regulator pin 3 output 5V

[retiredcaps]

Re: Insignia NS-24E730 LCD tv no power

I just add the photo with regulators location and those are the voltage reading:

N603, AZ1117D
Pin 1= 0
Pin 2= 3.3
Pin 3= 5

N607, 1117
Pin 1= 1.3
Pin 2= 2.5
Pin 3= 5

N602, 1117
Pin 1= 2
Pin 2= 3.3
Pin 3= 5

N606, 1117
Pin 1= 0.6
Pin 2= 1.8
Pin 3= 3.3

N608, 1117
Pin 1= 3.8
Pin 2= 5
Pin 3= 8.8

The above readings look fine.

Do you have an analog multimeter? There isn't much resolution in your readings? That is, 5 = 5.00 or 5.04 or 5.0001?

N604 -MP1482-buck regulator for main IC pin 3 output 1.8V
N605 -MP1482-buck regulator pin 3 output 5V

What is the reading on pin 2 on N604 and N605?

[suiramix]

Re: Insignia NS-24E730 LCD tv no power

N603, AZ1117D-3.3
Pin 1= 0.01
Pin 2= 3.30
Pin 3= 5.07

N607, 1117
Pin 1= 1.30
Pin 2= 2.52
Pin 3= 5.07

N602, 1117
Pin 1= 2.04
Pin 2= 3.30
Pin 3= 5.07

N606, 1117
Pin 1= 0.60
Pin 2= 1.80
Pin 3= 3.30

N608, 1117
Pin 1= 3.82
Pin 2= 5.06
Pin 3= 8.80

N604 and N605 has pin 2 voltage (input) 12.47V .
I agree with you , all voltages look fine.
Also I measured the input voltage for eeprom chip (MX25L3206L) is 3.28V !! could be a sign of corrupted firmware ??

[retiredcaps]

Re: Insignia NS-24E730 LCD tv no power

Trace the PON pin on the main board. The main board should be responsible for toggling this pin high (i.e 5V) so the rest of the secondary voltages on the power board can start.

[suiramix]

Re: Insignia NS-24E730 LCD tv no power

I just want to confirm, my friend has the exact same model (rev. A, nov. 2011) and experienced same symptoms pattern as mine:
-phase 1- the TV will turn off randomly,
-phase 2- restart by itself after 10-20 sec of normal function (same as LG, Samsung models)
-phase 3- could not be turn on, the standby led is flashing (indicates a malfunction on power supply / main board) or stay solid red (goes off when try to power on) and finally no power at all!
Definitely, some component gradually is getting worse (maybe bad solder joint?)

[retiredcaps]

Re: Insignia NS-24E730 LCD tv no power

Definitely, some component gradually is getting worse (maybe bad solder joint?)

It could be a bad solder joint. Look at all the "big" components on the backside.

As I mentioned in post #2, try pointing a fan to see if it helps.