I am trying to minimize new threads but if needed I can start a new thread, also note this post is a duplicate to a thread on Antiqueradios that I started in regards to injecting a composite signal. Finally note this is the same set that I just finished a full alignment on so I believe everything is working correctly.
To summarize the picture will not sync when injecting at test point C1 and am looking for help.
- I built an op-amp circuit to amplify the signal to match the voltage at C1 which is approx. -2.5 volts and 4 volts P-P. Note I added batteries to drive the signal down negative to -2.5 volts.
- Also used a Sencore VA62 to feed signal into the injection point. The VA62 allows you to adjust the drive voltage positive or negative. A positive signal is inverted and the color bars are wrong, a negative signal is correct but again I can not get the picture to sync. I set the VA62 to 4 volts P-P, note measuring at C1 shows no DC voltage, and again no picture sync.
- Finally tried moving back the injection point by lifting the anode of the video diode and then keeping L5, C18 in circuit, this made no difference.
Relevant parts of the schematic with Injection point and switch
Op-Amp
Composite jack and switch
