Core tips£ºVenus C542-1 TV treadmill phenomenon occurs, the grating normal
When a fault occurs, measured LNB voltage instability and low VT, +30V normal logging, logging M50346 ¢Ù pin voltage is normal. Disconnect the tuner VT-side test, find tuning voltage is still unstable, that tuner is not bad. Welding C1007, C1008, block resistance 10K ω, C1007 (0.22uF) leakage, with new 0.22uF/63V capacitors for later troubleshooting.