32" Insignia NS-L32Q -10A No power to inverter

[bikerbuddy]

Hello Guys I really need some help on this TV , This TV power on with black screen, I took the back cover off and ran some test on the power board, all the voltage that goes to the main Measure correctly as they are supposed to be.

I measure voltage on all the voltage regulator" I'll post below" T con looks ok .
but There is no power going to the inverter board from the P/S There is a separate transformer that supply power to the inverter,On the supply side of the transformer I get reading of


Input voltage out put voltage.
Pin 1 64.2 Pin 1 10.95
2 64.2 2 10.74
3 .759 3 10.53
4 63.4 4 10.73
5 63.4 5 10.89

Power supply output Voltage
5v sb = 5v
on/off = 3.2v
PDM = 2.98v
12 V = 12.29v
all ground = 001v
24v = 25.89v
P/s on = 4.75v
5V = 5.20

Voltage Regulator measurement
U702 016e5R 108418PE
Adj out in
.000 1.795 3.28

U703 G1084 L191
adj out 1n
.000 3.3 5.17

U 708 L123 g9084

ADJ OUT iN
6.97 8.22 12.29

U 7909 1117d 5.0E1

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

I FOGROT TO MENTION power that goes into the inverter transformer is as follows , looking at the board Left to right. Bottom pins
64.2
64.2
.759
63.4
63.4

On output side to inverter board
10.95
10.74
10.79
10.79
10.89

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

Sorry for the spelling error above " forget"

[tom66]

Re: 32" Insignia NS-L32Q -10A No power to inverter

So you have 25.89V, a little high, but nothing on the inverter?

[selldoor]

Re: 32" Insignia NS-L32Q -10A No power to inverter

Did you have it ALL connected when you did the measurements.
There is only a picture of half the inverter board - are there any fuses on the other half.
If the Inverter board is not working/disconnected the protection might lower the voltage
from the transformer.
Do you have any history of how the fault developed? Was it yours or did you buy it in to repair etc

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

here is a pic of the other half, and no there is no fuse on this board
I bought it to fix it ,

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

I did disconnect the protection and tried it , still cannot get the voltage up.
Now there is two wire feeding the inverter board can I just apply 24 volts to the pin that goes to inverter board?
pretty difficult to find a service manual for this tv.

[tom66]

Re: 32" Insignia NS-L32Q -10A No power to inverter

Looks to me like it sends high voltage to the inverter directly, the inverter isn't really an inverter but instead a ballast board, its job is to balance the current between the bulbs. You do not want to probe across the brown and blue as it will likely damage your DMM (>3000V typically.)

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

Tom do you think that this transformer is questionable? as you can see that pin 3 voltage is very low .759

[tom66]

Re: 32" Insignia NS-L32Q -10A No power to inverter

I don't know. 64V seems very high, that is probably just feedback error signal.

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

Is there any way to locate a schematic for this set that you know of ?any way
tomorrow I will go over every component part on the ballast board and see if I can find any thing unusual and will post back.
Thank you for your help Tom.

[budm]

Re: 32" Insignia NS-L32Q -10A No power to inverter

The two big wires (blue, brown) are the high voltage drive signal (it is not direct high voltage out put that drive the lamps directly, otherwise it will not be using regular 2-pin connector, that connector is not made to handle any thing in the 1000v or more range) that drives all the primary side of the small high voltage transformers on the inverter board.
If you look at the under side of the inverter board, you will more likely to see that all the primary side of the small transformers are connected to those two big wires.
Please post the pictures of the bottom side of the inverter board.
If it is the balancer board like SONY/SAMSUNG, there will be no need for the ballast caps on the secondary side of the small inverter transformers. I only have seen very few TV that use this kind of setup.

[tom66]

Re: 32" Insignia NS-L32Q -10A No power to inverter

It looks like typical 230V mains core, which is rated for 300VAC max, I believe. So yes, probably not 3000V as I originally said.

[budm]

Re: 32" Insignia NS-L32Q -10A No power to inverter

So if he does not even see the lamps flash on at all (it has to try to run before going into shutdown and send out the error), I would start checking the drive around that large transformer section. There should be some kind of fusible resistor that feeds the b+ to the two MOSFET's that drive the transformer. Since it it also has PFC, he needs to find out if the voltage on the large cap is around 400 or so when TV is powered on. If the PFC does not work,the backlights will not work either.

[bikerbuddy]

Re: 32" Insignia NS-L32Q -10A No power to inverter

sorry guys be back in a week or so Got the flu

[rlovison]

Re: 32" Insignia NS-L32Q -10A No power to inverter

I know this is an old thread but I'm having problems with the same model television. When I plug the unit in, sometimes the red led lights and sometimes it doesn't. If I press the power switch, most of the time nothing happens though sometimes I see a brief dim white flash. My power supply voltages are as follows:

on/off = .001
PDM= 3.32
12v = both are 12.38
all ground = -.001
24v = both are 25.13
P/S on = 4.71
5v = both are 5.18

I'm assuming the on/off is the backlight on/off signal which should be around 3.2v. Any idea as to where to look to find the problem? Thanks.

[budm]

Re: 32" Insignia NS-L32Q -10A No power to inverter

That ON/OFF (BL_ON) is generated by the main board, so something in the main board is not working. You can force the backlights to come on by disconnecting this line that goes back to the main board first (so we do not back feed the force on signal back to the main board), then use 1K resistor between the ON/OFF PIN and the 5V to force on the backlights, if nothing else is wrong with the main board, then you should be able see normal pictures on the screen. If you do not see anything on the screen, then you have more than ON/OFF control signal problem.

[rlovison]

Re: 32" Insignia NS-L32Q -10A No power to inverter

That ON/OFF (BL_ON) is generated by the main board, so something in the main board is not working. You can force the backlights to come on by disconnecting this line that goes back to the main board first (so we do not back feed the force on signal back to the main board), then use 1K resistor between the ON/OFF PIN and the 5V to force on the backlights, if nothing else is wrong with the main board, then you should be able see normal pictures on the screen. If you do not see anything on the screen, then you have more than ON/OFF control signal problem.

So if I understand you correctly, I solder a 1k resistor between the on/off pin and the 5v pin on the power supply board? Does it matter which 5v pin?

[budm]

Re: 32" Insignia NS-L32Q -10A No power to inverter

It does not matter, but you have to cut that wire that goes back to the main board or you will back feed the signal back to the main board which stuck low (the signal is being grounded by the main board)

[rlovison]

Re: 32" Insignia NS-L32Q -10A No power to inverter

It does not matter, but you have to cut that wire that goes back to the main board or you will back feed the signal back to the main board which stuck low (the signal is being grounded by the main board)

Thanks for offering your help.

ok, I disconnected the on/off lead coming from the main board (I just used a safety pin and was able to dislodge the metal clip from the plastic connector). I soldered a 1k resistor from the 5v pin to the on/off pin on the power supply where I now have 5.08v. I plugged the unit in and the backlight lit up for about two seconds then turned off. The led remains red with a black screen. Pushing the power button does nothing. Plugging the unit in gets the same behavior every time with the backlight though the red led doesn't always turn on.