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8753a phase lock lost error after warm up

Question asked by jtvdude on Mar 7, 2008
Latest reply on Mar 7, 2008 by jborges3
I have a 8753a that after  30 to 60 min get a error in the phase lock lost.
the voltage on tune goes from varying to 13 volts at tp1 . Have replaced and chked U7 U2 and Q4. Once the unit fails it takes over nite to reset. not just reset or remove power.  I have also notice spikes in the waveforms at tp1 tp2 tp 8 tp 9 and tp 5 . From what i could tell the signal looks good at base of q4.  these spikes are exactly like the image on crt at time. once the unit fails  it impossible  to track. The voltage starts to climb and instantly goes  to 13 volts. I have the service manuel and all test pass while unit is good.  sry reposted this in the right forum.  

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