Moving right along to the Color Amplifier alignment, below are the steps I took. Also posted are the Zenith Service manual and SAMS directions.
- Disconnect the tuner antenna input and set tuner in between channels
- Color switch on, color level set to the halfway point
- SAMS directions say to set the hue to the halfway point so I did this too
- Ground test point K
- Connect -6 volt bias to test point Q
- Connect the oscilloscope to the B&K 415 via the Horz and Vert inputs
- Connect demodulator probe (PR-151) from the B&K 425 Demod connector to test point U which is the cathode of the R-Y demodulator tube
- B&K 415 output set to Chroma, function set to Video
- Connect the B&K 415 signal to test point C1, I used the supplied RF Cable probe (TP-41) set to 75 ohms
- Set the sweep center frequency to 3.6mc, I kept the sweep width at max
- Note the B&K 415 does not have a 3.63mc marker
Here is my starting point, mostly a mess. The 3.0mc marker needs a lot of gain, and the either the 3.58mc has too much gain or the 4.1mc needs more gain.
Zenith Service Manual CM-105 (25MC33 Chassis)
SAMS directions (Folder 757, Set 4)
