Insignia NS-LCD47HD-09 Stuck in Stand by

[culcuhain]

Ok. I have now come into my possession an Insignia (yeah yeah, cheap brand) 47" TV that, when working, will be on the outside covered patio.
Got it in unknown working condition.
Plugged her in. LED goes purple (Blue and Red at same time) for a split second, 5 red flashes and then solid Red. Power button on side does not affect the tv. Checked all the buttons, they are all open until pressed then I have continuity. No burn marks or smells of burnt electronics. Caps aren't swollen (not always accurate).
I do not have a remote for her.
I have uploaded pics of the boards and board layouts.
I think there is an issue with the Power board and here is why:
CN903 (left plug in pic) volt readings
Pin 1 on/off: --
Pin 2 DIM: --
Pin 3 12v: 12.5v then quickly falls to under 1v.
Pin 4 12v: 12.5v then quickly falls to under 1v.
Pin 5-7 GND: --
Pin 8 24v: 24.5v then quickly falls to under 1v.
Pin 9 24v: 24.5v then quickly falls to under 1v.
Pin 10 PS On: --
Pin 11 5v: 4.95v (steady)
Pin 12 5v: 4.95v (steady)

CN904 Right Plug Top, connected to bottom plug via trace on underside)
Pin 1 -5 24v: 24.5v then quickly falls to under 1v
Pin 6-10 GND: --
Pin 11 Enable: --
Pin 12 On/Off: --
Pin 13 Dim: --

This to me is telling me at first glance that the power board has some issues with voltage regulation. I attached the service manual. Let's see what I can find out about the 12 and 24v falling to under 1v..... I will entertain all ideas and troubleshooting.... It is my night to watch the kiddo so I couldn't devote too much time troubleshooting. Tomorrow night the wife has to watch the kiddo so I get more time. Thanks!!

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Pin 1 on/off: --
Pin 2 DIM: --
Pin 10 PS On: --
Well if the power supply board is not getting the command signals that stay there then those Voltages will drop out.
So disconnect the Inverter board from the power supply board, then turn on the TV, then you should see those 3 signals which should swing from <1VDC to >2.5VDC and stay at that level, no command signals no switched Voltages.
You should read Basic LCD TV and Monitor troubleshooting guides.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Thank you. I put -- where I did not take a measurement. I will do that when I get home. Mow after some sleep and rereading your guide I think I have a better understanding....
It looks like my powerboard has the 5v standby and is awaiting the main board to send the signal to pin 10 on cn903. Once the power board receives the signal it knows to switch on the 5v switched, 12v and 24v. Without this signal they don't have the wakeup call. So the issue may lie in the main board if i get the voltages as you state after disconnecting the inverter boards?

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Ok Pin 10, PS_ON is about 55mv. So no power.
I jumpered the 5v standby to the PS_ON and the 12V and 24V hit 12.6 and 24.4. Ok. It looks like the power supply is leaning towards being good. Time to track that circuit.... more to come.

[CapLeaker]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

bad main board.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

bad main board.

Thank you. That is what I was thinking. Now the question becomes is the main fixable or just replace it?

[CapLeaker]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

That depends on what main board, how expensive a new one is, if you have smd rework tools and how comfortable you are working on that main board.

If you feel comfortable trying to repair it, I would suggest you post another high resolution, straight shot from the main board and remove that large tin shield, so we can see inside there. I also would try to find the EEPROM on the main board and freeze it with a can of air upside down, then turn the TV on.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

I have no smd reworks tools right now. I decided to order a new board. Will be here end of the week. Will report back then.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Update. The new Main Board showed up. Installed her. Same issue. Time to do some more digging.
I have found one of the culprits.
I have uploaded the pic of the connector on the main board from the keyboard and IR.
Pin Voltage
GND 0.00
5V 3.3
IR 3.3
B bouncing. .171mv--.4v
R 1.75
GND 0.00
PS 3.3
CH+ 3.3
CH- 3.3
VOL+ .50mv
VOL- 3.3
Menu 3.3
Sel 3.3

Hmm... I disconnected the keyboard connector and vol+ goes to 3.3v.
Since I don't have a remote for this tv I quickly jumpered the PS to the GND and low and behold I get a beautiful blue light but no back lights. The same happens with the old Main board. So it looks like the vol + switch on the Keyboard is wonky. Looks like the old main board, might have been good... back to testing the voltages from the main post.

CN903 volt readings after jumping PS and GND
Pin 1 on/off: 1.4v then falls to .50mv
Pin 2 DIM: 1.4v then falls to .50mv
Pin 3 12v: 11.4
Pin 4 12v: 11.4
Pin 5-7 GND: 0.00
Pin 8 24v: 24.6
Pin 9 24v: 24.6
Pin 10 PS On: 3.5
Pin 11 5v: 4.95v
Pin 12 5v: 4.95v

CN904 Right Plug Top, connected to bottom plug via trace on underside)
Pin 1 -5 24v: 24.5v
Pin 6-10 GND: 0.00
Pin 11 Enable: 2.5
Pin 12 On/Off: 1.4v then falls to .50mv
Pin 13 Dim: 1.4v then falls to .50mv

So now it looks like there is an issue with the Inverter part of the PSU/Main Board. Looking at the service manual I have a lot of parts to test on the inverter side. That will be another night.

Anybody see anything I might have missed?

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Pin 12 On/Off: 1.4v then falls to .50mv. This is the BL-ON signal
Pin 13 Dim: 1.4v then falls to .50mv
Those two signals which are generated by the main board should not drop out.

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

BTW: "CN903 volt readings after jumping PS and GND" Which pin did you jump to GND.
You have PS-ON of 3.5V present so that is why you are getting the 24 for the inverter and 12V for the audio circuit.

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

You can force on the power supply and the Inverter circuit by using 2 1K resistors, but you MUST disconnect the cable between the main board and the power supply board first, then connect the resistor between the 5VSTBY and the PS-ON, and another resistor between the ON/OFF and the 5VSTBY.
If the backlighs still does not come on then you will need another resistor between DIM and 5VSTBY.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

BTW: "CN903 volt readings after jumping PS and GND" Which pin did you jump to GND.
You have PS-ON of 3.5V present so that is why you are getting the 24 for the inverter and 12V for the audio circuit.

So once I momentarily jumped the PS to GND on the keyboard connector. I get the blue light. PS_ON voltage shows up on the PSU Board. the 12V and 24V show up on the PSU board. the On/Off and DIM hit 1.4V then falls to 50mw.
This looks like it by passes the Vol+ switch being stuck. The Red Led on the front goes to Blue. It leads me to believe the keyboard is bad and the VOL+ button is stuck not allowing the Power On Button signal to hit the main board. I disconnect the keyboard and the voltage on the main board for Vol+ goes from 50mv to 3.3v. This is just one of the problems.

Now I am rambling.

You can force on the power supply and the Inverter circuit by using 2 1K resistors, but you MUST disconnect the cable between the main board and the power supply board first, then connect the resistor between the 5VSTBY and the PS-ON, and another resistor between the ON/OFF and the 5VSTBY.
If the backlighs still does not come on then you will need another resistor between DIM and 5VSTBY.

I will try this tomorrow after work. It looks like the issue is with getting the DIM signal from the main board telling the backlights to fire and we will trick the PSU into thinking she is getting the signal?

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

From poSt 1:Checked all the buttons, they are all open until pressed then I have continuity.
So now do they still check out OK?
what resistances are you getting between the two open contacts on each switches?

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

Looks like 18.4K ohm across all except vol+. Vol+ shows 0.6K Ohms.
Did the checks from p24 of the manual except for IC901 and IC903 and the transformer T902. Not sure how to test those ICs. All others tested fine with no shorts. I think it is time to crash and regroup tomorrow. thank you for your help.

[budm]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

The resistance between the two terminals of the normally open switch should show open circuit, the VOL+ is bad for sure.
You did remove the cable to the board first, right.

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

My bad. It was still connected. I disconnected it. All show OL except for Vol+ is it showing 0.6K ohms. So bad switch. Time for bed. 445 cones quick.

[CapLeaker]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

is it possible that you got a bad main board? Did you purchase it from a seller with good reputation?

[culcuhain]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

I will try the resistor trick tomorrow night as well as checking the other board again and see if the BL_ON is doing the same thing. I wont get anything done tonight... too tired and that is where I make mistakes. I will update everyone over the weekend!

[CapLeaker]

Re: Insignia NS-LCD47HD-09 Stuck in Stand by

PSon, BLon and DIM signals are coming from the main board.