Insignia NS-L37Q-10A No Picture No Sound

[jreb10]

This set was purchased in April 2009. Currently it appears to power up to some level, as the LED goes from red to blue as it should. There is no picture or sound from my satellite input or my antenna input.

In the dark I can see a faint backlight, but there is no trace of any image on the screen.

I did remove the back and look over the boards. All the capacitors seem to be rated for 105C. None look bad to my eye, nor can I see any component that appears suspect. Board pictures I have taken so far appear below.

I'm not sure how to proceed. I am guessing that I want to test the power board outputs, but I'm not sure exactly how so I am asking for advice. I can handle a multimeter. Thanks in advance for any suggestions.

[PlainBill]

Re: Insignia NS-L37Q-10A No Picture No Sound

This set was purchased in April 2009. Currently it appears to power up to some level, as the LED goes from red to blue as it should. There is no picture or sound from my satellite input or my antenna input.

In the dark I can see a faint backlight, but there is no trace of any image on the screen.

I did remove the back and look over the boards. All the capacitors seem to be rated for 105C. None look bad to my eye, nor can I see any component that appears suspect. Board pictures I have taken so far appear below.

I'm not sure how to proceed. I am guessing that I want to test the power board outputs, but I'm not sure exactly how so I am asking for advice. I can handle a multimeter. Thanks in advance for any suggestions.

You, sir are a genius. That touch of the final picture showing the pinout of CN902 is a very nice touch.

This is a slightly unusual power supply, but shouldn't present any difficulties. With AC power connected, but the TV off, check the voltages on CN902. You should be able to make contact through the top of the female connector. Use any of the GND pins for the black probe. In cases where two pins are labeled the same (ie, +5V), it isn't necessary to measure both. I would expect you would see voltages only on +5V and possibly PS_ON. Now turn the TV on and repeat. You should see voltages on all non-Gnd pins.

If these check out, it will be time to check the main board - I see several LDO regulators that should be checked.

PlainBill

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

AThank you for your complimentary response. I try.

Here are the voltage readings from CN902:


Pin Plugged In Powered Up
O/F 0 3.27
DIM 0 3.31
+12 0 12.27
+12 0 12.27
GND 0 0
GND 0 0
GND 0 0
+24 0 24.8
+24 0 24.8
PS_ON .10 4.69
+5 5.17 5.15
+5 5.17 5.15

Her are a couple more photos of the main board.

[PlainBill]

Re: Insignia NS-L37Q-10A No Picture No Sound

AThank you for your complimentary response. I try.

Here are the voltage readings from CN902:


Pin Plugged In Powered Up
O/F 0 3.27
DIM 0 3.31
+12 0 12.27
+12 0 12.27
GND 0 0
GND 0 0
GND 0 0
+24 0 24.8
+24 0 24.8
PS_ON .10 4.69
+5 5.17 5.15
+5 5.17 5.15

Her are a couple more photos of the main board.

Those numbers indicate a power supply that is working properly.

On the attached picture the orange circles indicate LDO regulators. What are the part numbers of these? Also, the pins are numbered (pin 2 is the tab), With power on, measure the voltage on each pin, and report it. I believe pin 1 is the input, pin 3 is the output, and the tab is ground.

The yellow circles indicate bucking regulators. What is the part number of the 8 pin ic?

PlainBill

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

Thank very much for your guidance.

The two bucking regulators have the same part number on the 8 pin IC, as follows:

SC4524B
0841
V34527

The LDO regulators have different part numbers. The "northern" one is:

L013
G1084-33

When I power up and do a voltage check, with the power supply GND as reference, I get the following:

Pin 1: 0
Pin 3: 5.11
Tab: 3.22

Here is the info for the "southern" one:

1084
-18PE
995H8R

Pin 1: 0
Pin 3: 3.27
Tab: 1.78

[tom66]

Re: Insignia NS-L37Q-10A No Picture No Sound

Some more things to check:

Confirm the part numbers of the 8-10 pin ICs circled in black.

Also, test the diodes circled in red. To test: Turn TV off. Set your meter to diode mode. (If it doesn't have a diode mode, set it to the 2kohm range.) Place one black lead on one terminal and red lead on other terminal. Record reading. Reverse the leads; record the reading.

If the diode is good, you should get around 200 - 800 one way, and infinity the other way.

[PlainBill]

Re: Insignia NS-L37Q-10A No Picture No Sound

Thank very much for your guidance.

The two bucking regulators have the same part number on the 8 pin IC, as follows:

SC4524B
0841
V34527

The LDO regulators have different part numbers. The "northern" one is:

L013
G1084-33

When I power up and do a voltage check, with the power supply GND as reference, I get the following:

Pin 1: 0
Pin 3: 5.11
Tab: 3.22

Here is the info for the "southern" one:

1084
-18PE
995H8R

Pin 1: 0
Pin 3: 3.27
Tab: 1.78

There are four LDO regulators. Are these the readings of the two between the tuner and the edge of the board, or the two closer to the middle of the board?

Also, it's obvious I was wrong about the pinout.

PlainBill

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

To PlainBill,

Sorry for the oversight on my part. I fixated on the two near the middle of the board, and gave you those readings.

For the two near the edge of the board:

North One
K431
G9084
Pin 1: 6.94
Pin 3: 12.27
Tab: 8.17

South One
AZ1117D
-5.OE1
9902K77
Pin 1: 0
Pin 3: 8.17
Tab: 4.95

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

For tom66:

Thank you for helping me.

The "north" IC number is:
4449
BA811A

The "south" IC number is:
194B
0838
Z963


I tested the diodes with the diode setting on the multimeter. Both the diodes have the same numbers on them, as follows:

0695
SM340A

"North" diode readings: .098/.089

"South" diode readings: .039/.051

These don't look too good to me.

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

I worked up the courage to unscrew the main board and flip it over for inspection. I found what looks like a solder bridge.

This lies underneath the large heat sink in the other photo.

Should I conclude that I am in the market for a new main board?

[tom66]

Re: Insignia NS-L37Q-10A No Picture No Sound

For tom66:

Thank you for helping me.

The "north" IC number is:
4449
BA811A

The "south" IC number is:
194B
0838
Z963


I tested the diodes with the diode setting on the multimeter. Both the diodes have the same numbers on them, as follows:

0695
SM340A

"North" diode readings: .098/.089

"South" diode readings: .039/.051

These don't look too good to me.

South IC datasheet:

No idea on the North IC. Are you sure on that part number?

Those diodes might still be good, but the circuit is interfering with them. Unfortunately, you'll have to lift one leg to measure them, and this is tricky.

A simpler approach. Measure the voltages across all the highlighted components while TV is on. For the big electrolytic capacitors, you may have to do it with the main board flipped over. Place red on one side, black on other. Don't worry about polarity.

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

Thanks for the reply tom66.

I am sure of the number on the north IC, in fact it was the easier of the two to read.

I see 4 components that you squared in red. I hope I did not miss any others.

For the capacitors, the big one on the left measured 24.5, the one on the right measured 5.1.

For the two remaining components, the one on the left measured 5.12, the one on the right measured 3.27.

[tom66]

Re: Insignia NS-L37Q-10A No Picture No Sound

I see 4 components that you squared in red. I hope I did not miss any others.

For the capacitors, the big one on the left measured 24.5, the one on the right measured 5.1.

For the two remaining components, the one on the left measured 5.12, the one on the right measured 3.27.

Yep only 4, those voltages seem okay.

I was using MS Paint on an office computer - and couldn't figure out how to make the boxes bigger.

At the very least, the 10pin converter is okay, and the 8pin one *probably* is.

Is there any chance of you getting the cover off the shield on the main board. There's probably a processor under there.

[jreb10]

Re: Insignia NS-L37Q-10A No Picture No Sound

I took the cover off on the main board. Here are a couple of photos.

[ryghigh]

Re: Insignia NS-L37Q-10A No Picture No Sound

Did you get this resolved? I'm having the same issue.

Thanks,
Ryan