Zenith Color Roundie Alignment with B&K 415

[bhegges]

Looking for some help and hope maybe this thread will help others in the future. I have repaired a Zenith 25MC33 chassis to working condition. I would like to go through the exercise of alignment, or at lease the motions to see where it is at. I understand care is needed and there is risk of making things worse. With that out of the way I have the SAMS folder and the Zenith CM-106 service manual, also the B&K 415 instruction Manual.

I am trying to start with IF and Trap alignment but immediately am stuck. Probably a simple setup mistake but so far I get no measurable signal on the oscilloscope. Making changes to the B&K 415 has no affect.

Per the instructions here is what I have done:

• Grounded the 3 test points
• Nothing is connected to the tuner and set it in-between channel 3 & 4.
• Feeding signal from the B&K 415 via the direct probe to test point G
• I have tried with and without the resistor/capacitor assembly as per the Zenith directions
• Note this is the only connection from the B&K 415 as I have highlighted in yellow below
• I tested the B&K 415 cable end to end and it measures approx. 10K resistance on both the ground and signal clips
• Oscilloscope is connected to test point C1

The last pic is measuring at test point C1 while operation normally with a cross hatch video signal.


B&K 415 Setup





Zenith CM-106 Directions




Scope: