Insignia NS-LCD32-09 keeps turning off and on again

[jcg]

I figured it was the power supply board so I bought one online but the problem is the same regardless of if I use the original power supply board or the one I just bought.

Turn the TV and then after a bit it will turn off, then awhile later it's back on again. I unplugged the cable off the top of the power supply board (when looking at it from the back of the TV) that goes off to the left into the center of another board (maybe the backlight board). Same problem.

There is also a cable coming off the top of the main board that goes up to the top of the TV in the center which I'm guessing is what drives the LCD panel. Disconnecting that also makes no difference.

So the only thing left is the main board. Can disconnect the cable that goes to it as obviously nothing works then. Is there anything on the main board that someone could point me at the would cause this type of issue?

jcg

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

We need to see the pictures of the whole back side of the TV so we can see how all the boards are connected together and understand all those boards you connected and disconnected.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

Sorry it took awhile to get back on this but here is the picture of the back of the TV that shows the cables I was talking about.

jcg

We need to see the pictures of the whole back side of the TV so we can see how all the boards are connected together and understand all those boards you connected and disconnected.

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK, the top right connector of the power supply that goes to the main board on the right of the power supply, does that connector on the power supply have any label for each pins to tell us what they are? We will need the DCV of the PS-ON pin, 5VSTBY (if it uses 5V for standby Voltage).

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

Yes the connector (going from left to right) has 1 green wire (can't read the signal name), 1 blue wire (signal name ends in "DIM", 2 red wires (12V), 3 black wires (Gnd), 2 orange wire (24V), 1 white wire (PS), and 2 yellow wires (5V).

I measured the voltage and the 5V is always on, and the PS signal goes away when the TV turns off, the 24V signal slowly goes to 0 when the TV turns off, and 12V immediately goes to 0 when the TV turns off. This is the same regardless of whether I install the new Power supply board I bought.

So what next?

jcg

OK, the top right connector of the power supply that goes to the main board on the right of the power supply, does that connector on the power supply have any label for each pins to tell us what they are? We will need the DCV of the PS-ON pin, 5VSTBY (if it uses 5V for standby Voltage).

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

So the PS-ON command from the main board is there then disappear, it is generated by the main board to turn on the 12V (for sound) and the 24V for the inverter board.
You will have to do visual inspection of the main board next, look at top and bottom side of the board to see if it has any bad solder joints, burnt parts, and etc.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

Does anyone have a schematic for the main board? There are thousands of discretes on the top/bottom, so this will be like finding a needle in a haystack. There are no obvious burnt parts that I can see. I'll have to bring the board into work and look under a microscope to see if I can spot any bad solder joints, unless someone can point me to specific parts??

I could also cut the PS ON wire and tie it directly to 5V wire to see if the TV stays on in that scenario.

jcg

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

So is there any chance someone has a schematic for this or knows what part drives the PS_ON signal? I looked at the board under a microscope today and didn't see any obvious bad solder joints.

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

You can try force on with 500~1K resistor between PS-ON and the 5VSTBY after disconnecting the PS-ON wire going back to the main board, if everything else on the main board is OK then you should see the backlights, the image on the screen, the sound, if not then you have more than just PS-ON signal problem.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK, so I cut the PS_ON wire to the Power supply and tied it directly to 5V and the TV works again. I can still turn it off and on with the power button, so I guess this is a kludge fix.

I would still like to find what is wrong on the main board in the circuit that is driving the PS_ON circuit. Anyone know how to get a schematic for the main board? Or anyone know what resistor / cap I can check that drives this signal. It must be some part that is going bad as it heats up and then cools off and starts working again (since the the TV goes from the on to off to on state at some random time interval).

jcg

Does anyone have a schematic for the main board? There are thousands of discretes on the top/bottom, so this will be like finding a needle in a haystack. There are no obvious burnt parts that I can see. I'll have to bring the board into work and look under a microscope to see if I can spot any bad solder joints, unless someone can point me to specific parts??

I could also cut the PS ON wire and tie it directly to 5V wire to see if the TV stays on in that scenario.

jcg

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK jumped the gun on that post. After leaving the TV on for longer it's doing the same thing even though I have PS_ON tied to 5V. The 24V and 12V don't go away when the TV turns off either, so any other ideas? What does the green wire (on the far left of the connector) or the blue wire (right next to the green wire) do?

jcg

OK, so I cut the PS_ON wire to the Power supply and tied it directly to 5V and the TV works again. I can still turn it off and on with the power button, so I guess this is a kludge fix.

I would still like to find what is wrong on the main board in the circuit that is driving the PS_ON circuit. Anyone know how to get a schematic for the main board? Or anyone know what resistor / cap I can check that drives this signal. It must be some part that is going bad as it heats up and then cools off and starts working again (since the the TV goes from the on to off to on state at some random time interval).

jcg

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

"OK, so I cut the PS_ON wire to the Power supply and tied it directly to 5V and the TV works again. I can still turn it off and on with the power button, so I guess this is a kludge fix." But the power supply is still full on because the PS-ON is present even when the power switch is activated off, the BL-ON turns off the backlights circuit but the PFC Booster is full on. So basically the power supply is full on 24/7 even when the TV is off unless you unplug the power cord..
The way to find out without the diagram is to trace that PS-ON pin on the main board, it should ending up at the Collector of the switched transistor/s that is turned on and off by the processor.
Another way to cheat is to look at the LDO regulator IC to see which one goes high on the input pin when power switch is activated, but the PS-ON forced on resistor has to be removed and not connected during this search for the high signal.

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK jumped the gun on that post. After leaving the TV on for longer it's doing the same thing even though I have PS_ON tied to 5V. The 24V and 12V don't go away when the TV turns off either, so any other ideas? What does the green wire (on the far left of the connector) or the blue wire (right next to the green wire) do?

jcg

I need to see good clear pictures of the connector, since now you have 12V and 24V but no backlights, it may mean that the BL-ON signal is also gone now too.

"The 24V and 12V don't go away when the TV turns off either" that is because the power supply is forced on so the 12V, 24V will be on 24/7 as long as the TV is plugged into the outlet.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

I'll try to get a very close up picture tonight and post it.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

Here is a closeup of the top right PS connector that you requested.

I'll try to get a very close up picture tonight and post it.

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK, I found good picture at SJ:
http://www.shopjimmy.com/vizio-insig...wer-supply.htm
CN902 ON/OFF pin is the backlights ON/OFF control pin.
So see if it has >2V on that ON/OFF pin.

[jcg]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK I'll look at this tonight when I get home. I think it is the green wire on the far left of CN902 that I sent a pic of. There is silkscreen to the very left of the edge of CN902 that says ON/OFF.

[budm]

Re: Insignia NS-LCD32-09 keeps turning off and on again

OK I'll look at this tonight when I get home. I think it is the green wire on the far left of CN902 that I sent a pic of. There is silkscreen to the very left of the edge of CN902 that says ON/OFF.

That is the one, it is the backlights on/off (BL-ON) control pin.