A Panasonic TC-2150RS color TV, boot a short time to work properly, the conversion channel without exception (the conversion channel instantly due to the role of a slight noise squelch, and sound short off). With the passage of time, the conversion channel instantaneous screen does not show a black screen, but left dark right light, and then convert the channel instantaneous screen dark part of the proportion of gradually reduced until about half of each. At this point can not convert the channel, and finally convert the channel that is automatically shut down, if not convert the channel, then a few minutes after the two automatically shut down and automatically boot to the third automatic shutdown will no longer boot. Turn off the power for a moment after the boot failure to reproduce.q3sservice manual download site
The occurrence of the fault is more consistent, so the possibility of excluding Weld or poor contact and suspected that a component caused by poor thermal stability. Taking into account the TV conversion channel, squelch and secondary on / off and other actions are controlled by the CPU, so to determine the fault and CPU.q3sservice manual download site
First check the CPU (MN152811TZX) working conditions, measured its power supply voltage, just when the normal start 5V, then gradually decreased to about 4.3V, then slow down the speed, a few minutes after the automatic shutdown. Check the CPU power supply IC802, found that the printed circuit board has overheated signs (the machine IC802 use 78L05, shape and similar to the small power transistor), touch the feeling of higher temperature. Disconnect the IC802 load, the output is normal. Suspected 5V load leakage or overcurrent, one by one off the load test, did not find a significant over-current phenomenon, to determine the IC802 bad. Replace with a 7805q3sservice manual download site
IC802, continuous test machine hours failure no longer occurs, troubleshooting.q3sservice manual download site