Insignia NS-F27C 27" Flat Tube TV
I repaired it!
My Insignia TV set started showing the same problem reported here, after a static discharge sparked when my wife was cleaning the TV with a cloth.
The information provided by bill47 proved to be very useful. I tried to find the data sheet of the large 64 pin IC, TDA973, I found the TDA 9351, which may be from the same family. I measured the voltage at pin 6 and it was approx. 0.2V. I imagined that if I forced that voltage to a higher value the IC would believe that no button is deppressed and so return to normality. From bill47 comments and my measurements of resistance to ground with the TVset off I estimated that a voltage divider was formed with a 3.3K resistor from +3.3V to pin 6 and 180 ohm to pin 6 to ground. In those conditions, I calculated that if I add a 18 ohm resistor from 3.3V to pin 6 I should force the voltage at that pin to 3V. I first tried with a 120 ohm resistor between pin 61 (peripherial power supply in) (+3.3V) and pin 6. This moved the voltage to 1.7V, the failure persisted, but the effect was different, as if another button, located at the rigth of the Input button, was permanently depressed. This showed me that I was in the right trak. I refined my calculations and replaced the 120 ohm resistor to 15 ohm. That raised the voltage at pin 6 to 2.5 V, and solved the problem. The front panel buttons were disabled (except for the Power button), but that is not a problem, I never use them, I always use the remote control. So I can continue enjoying my Insignia TV set! Thank you bill47 and all the other people who posted their comments.
Oct 18, 2007 |
Insignia IS 20" TV040919 TV