Insignia ns-32e570a11

[jkomorek]

Trying to figure out what's wrong with this TV. I already took a chance and replaced the power supply, but I still experience the same problem.

Here is a description of the problem. When I plug in the TV, the power indicator lights up red. Then I switch the TV to on and the power indicator turns blue, and remains blue. Seconds after the TV is turned on, the backlights flash then remain off; while again, the power indicator remains blue.

I can provide more details about the measurements which I have taken from the power supply, but in summary, after switching the TV to on the PS-ON input gets a steady input and I am reading the standard 5v standby and 12v voltages. There is another voltage which may be a signal from the Main Board to the PS as it jumps when I turn on the TV then drops immediately after the lights flash, but unfortunately I cannot find any schematics or service manuals for this TV.

Any advice? After foolishly replacing the PS I hate to swap out the Main Board as well - at least without more confidence that this is the problem.

Oh, and I the backlights appear to work fine. I uplugged them one at a time and the both flashed. Also I crossed some wires by accident on the PS a while ago and for about 30 seconds the TV seemed to be working fine.

I will attach photos in a minute.

[jkomorek]

Re: Insignia ns-32e570a11

Here is a back and front of the Main Board plus an overall photo.

[budm]

Re: Insignia ns-32e570a11

There should be another signal for the BACKLIGHTS ON (BL_ON or INV_ON) which comes from the main board and routed through the power supply board connector on the way to the inverter board. So look for that signal, it should be >3vdc for ON. Since this TV uses LED for backlight, so it does not have the high voltage inverter circuits, but it has multi power supplies for driving the LED strings.

[jkomorek]

Re: Insignia ns-32e570a11

There should be another signal for the BACKLIGHTS ON (BL_ON or INV_ON) which comes from the main board and routed through the power supply board connector on the way to the inverter board. So look for that signal, it should be >3vdc for ON. Since this TV uses LED for backlight, so it does not have the high voltage inverter circuits, but it has multi power supplies for driving the LED strings.

Thanks, Bud.

Here is a photo showing the PS side of the Main Board connection. There are 12 pins, half of which are labelled. Of these pins I have noticed at least two which start round 0v, then when I turn the TV on they jump to 5v and drop back down to 4.5v after the balcklights flash.

The PS does have three markings for:
SNGD
BL_ON
BL_DIM

However, I am not certain what part of the board they are labeling. Below the labels are three transistors attached to a heat sink so I was thinking that these are related, but I am having a difficult time understanding how.

Here are their readings:

Before turning on the TV:

T1: 0v, 5v, 0v
T2: 5v, 14.3v, 5v
T3: 14.1v, 0v, 13v

After Turning on the TV:

T1: 0v, 5v, 0v
T2: 5v, 13v, 5v
T3: 13v, 12.3v, 10.7v

[jkomorek]

Re: Insignia ns-32e570a11

Sorry, I forgot the attachment. If You want a better photo, please let me know and I will grab more/less of the board.

[jkomorek]

Re: Insignia ns-32e570a11

After looking at the board for a while I realized that the three markings do indicate which pins on the CN2 connector between the PS and Main Board are BL_ON , BL_DIM, and "8-11-12-SNGD".

When I turn plug in the TV, the voltage on BL_ON is of course 0. When I turn on TV it jumps to 5v. Then around the time when the backlights flash it drops to around 2v and immediately comes back up to about 4.7v.

[budm]

Re: Insignia ns-32e570a11

At 4.7v for the BL_ON and it stays there, then the backlights LED should stay on also, so that means there is problem with the LED backlights power section.
How about bl_dim, what do you get?

[selldoor]

Re: Insignia ns-32e570a11

Please can you post a clear picture of the front and back of the power board

[jkomorek]

Re: Insignia ns-32e570a11

So I decided to go for it and replace the main board - still have the same problem. At this point I have replaced both the main board and the PSU and am still getting a flash on the backlights then nothing.

With the new main board, BL_ON reads 4.8v and BL_DIM 5.02v. I will get a good picture of the power board.

[jkomorek]

Re: Insignia ns-32e570a11

Please can you post a clear picture of the front and back of the power board

Here are two broad view pictures of the power supply and two photos focused in on the two connectors going out to the backlights.

I apologize for the lighting, but I was trying to avoid using the flash. If the quality isn't good enough I will try to figure something out.

[selldoor]

Re: Insignia ns-32e570a11

You are right - pics are not clear enough - you need to take them in good daylight.
However I am not sure they are going to help. You have tried two power supplies and two main boards and still get the problem. It should then be down to the lights but you said at one point they came on and stayed on- right?
Can you recall what you were doing and where when that happened?

[jkomorek]

Re: Insignia ns-32e570a11

You are right - pics are not clear enough - you need to take them in good daylight.
However I am not sure they are going to help. You have tried two power supplies and two main boards and still get the problem. It should then be down to the lights but you said at one point they came on and stayed on- right?
Can you recall what you were doing and where when that happened?

Yes, I was probing the old power supply and accidentally shorted something. I don't know what circuits I crossed though and could not reproduce despite several attempts.

[lakeman1]

Re: Insignia ns-32e570a11

Just FYI: I had a friend with an Insignia NS-32E570-A11 with a backlight problem, and it turned out to be one of the actual LEDs in the backlight array was burned out, causing some sort of over-voltage condition that made the backlight sometimes work, and sometimes just flicker for a moment at TV startup and then turn off.

We took the panel apart and bypassed the one bad LED (it had a dark spot on it and failed continuity (second from the right in the photo) - you can test each LED with a continuity tester and see them light up!), and now the TV/backlight works!

Be aware this is tricky bypassing the bad LED, as it is ultrasonically welded to the LED array strip (same technique used to make ICs), so you need to be a very good solderer to bypass it without it breaking the connection.