My Insignia NS-50LC240A13 quit the morning after a night time electrical storm in our area. At first, it randomly popped up menus and changed options as if someone was changing settings with the remote. After a bit, the menu popping up would cease and it would operate normally for while, from 5 to as much as 30 minutes at time. After a few power on reset cycles, it would no longer turn on at all.
I took it down, got the the back off and found no visible problems. The power supply was working (5VST at 5V, 12V rails OK) and the PON pin was at 2.95V - the main board was signally for the power supply to be on. The BON and PWM pins were low and the back light was off. To check the power supply and the back light, I pulled the cable from the main board and pulled PON, BON and PWM to 3.3V with an external supply and the back light came on. Thus the power supply board and back light are good.
This TV uses the 569MF0801A model main board and has several LM1117 type regulators powered from 5VST, 5V and 12V. The output voltages of each of these measure what appears to be valid voltages; 3.3V, 2.5V, 1.8V and 5V for the tuner (via dropping resistor from 12V to LM1117 regulator). However, the temperature rise on the 3.3V regulator powered from the 5VST is noticeable. I pulled the main board off the TV and powered it from a 5V bench supply and the standby rail pulled about 650mA which seems high to me. Any one have an idea as to what the current draw on the 5VST rail should be? I suspect there was damage to the main signal processing chip via a voltage surge on the HDMI input. (We lost one of the HDMI inputs on another TV in a different room and also an HDMI switch that was connected to that TV the same night). I did check the clock oscillator circuit with an oscilloscope and have a good clock when I power up the chip via the 5VST rail. I have not yet checked for clock and data activity on the EEPROM or FLASH chip to see if the main processor is trying to load the code, but will do so the next time I work on this.
One oddity I noticed was after having the TV opened up on the bench and connecting and disconnecting AC power many times over several days, the back light never came on. After thinking about the menus popping up and thinking that the button control panel might be at fault, I unplugged the button panel and the back light popped on. It stayed on for a minute or two and then went back off. I never could get that to repeat and the TV is completely dead as before.
I emailed Insignia trying to obtain a service manual but received the non-helpful response that they would not sell me a service manual as the information was proprietary, so no help there.
So in summary, my questions are:
1. Anybody know where I can get a service manual for this TV?
2. Anybody know what the standby current on 5VST should be for a known good set?
3. Anybody know what the main signal processor chip is and where I could find a replacement? (I have not yet removed the heat sink to look for markings).
Thanks in advance for any help provided.
Ronnie
I took it down, got the the back off and found no visible problems. The power supply was working (5VST at 5V, 12V rails OK) and the PON pin was at 2.95V - the main board was signally for the power supply to be on. The BON and PWM pins were low and the back light was off. To check the power supply and the back light, I pulled the cable from the main board and pulled PON, BON and PWM to 3.3V with an external supply and the back light came on. Thus the power supply board and back light are good.
This TV uses the 569MF0801A model main board and has several LM1117 type regulators powered from 5VST, 5V and 12V. The output voltages of each of these measure what appears to be valid voltages; 3.3V, 2.5V, 1.8V and 5V for the tuner (via dropping resistor from 12V to LM1117 regulator). However, the temperature rise on the 3.3V regulator powered from the 5VST is noticeable. I pulled the main board off the TV and powered it from a 5V bench supply and the standby rail pulled about 650mA which seems high to me. Any one have an idea as to what the current draw on the 5VST rail should be? I suspect there was damage to the main signal processing chip via a voltage surge on the HDMI input. (We lost one of the HDMI inputs on another TV in a different room and also an HDMI switch that was connected to that TV the same night). I did check the clock oscillator circuit with an oscilloscope and have a good clock when I power up the chip via the 5VST rail. I have not yet checked for clock and data activity on the EEPROM or FLASH chip to see if the main processor is trying to load the code, but will do so the next time I work on this.
One oddity I noticed was after having the TV opened up on the bench and connecting and disconnecting AC power many times over several days, the back light never came on. After thinking about the menus popping up and thinking that the button control panel might be at fault, I unplugged the button panel and the back light popped on. It stayed on for a minute or two and then went back off. I never could get that to repeat and the TV is completely dead as before.
I emailed Insignia trying to obtain a service manual but received the non-helpful response that they would not sell me a service manual as the information was proprietary, so no help there.
So in summary, my questions are:
1. Anybody know where I can get a service manual for this TV?
2. Anybody know what the standby current on 5VST should be for a known good set?
3. Anybody know what the main signal processor chip is and where I could find a replacement? (I have not yet removed the heat sink to look for markings).
Thanks in advance for any help provided.
Ronnie
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