Fault phenomenon: After automatic channel selection, the station cannot be locked. After manual channel selection, once the channel is changed, the signal immediately drifts. If you press the fine-tuning + button again, the original station signal can be retrieved, but when you switch channels and return to the original channel, the signal drifts again.
Philips TV, unable to lock after automatic channel selection
Analysis and treatment: Apparently, this kind of fault phenomenon indicates that the Automatic Fine-Tuning (AFT) circuit of the color TV is abnormal. The fault point is generally due to the image intermediate frequency resonant circuit L152 or the AFT frequency discriminator phase-shift resonant circuit L152 being out of tune. Also, if the resonant frequency of either one deviates from 38 MHz, the aforementioned phenomenon will occur. This is usually caused by the oxidation failure or reduced capacity of the internal capacitor in the resonant circuit. To reduce the likelihood of future faults, the same model components L151 and L152 should be replaced. After replacement, power on for testing, and the fault of the color TV is resolved.
Beijing Philips TV Repair Center released on September 9, 2011.