Zenith Color Roundie Alignment with B&K 415

[bhegges]

Originally Posted by old_tv_nut

In that case, the 75 ohm setting may work when used with the Zenith RC circuit added. The 75 ohm setting may actually just be a direct feed through.

I found some info on the TP-41 cable here: https://www.youtube.com/watch?v=kRaYG-dmCPw and have drawn it below. Note when using this cable connected to the tuner mixer grid input I have the B&K 415 set to ch4 and am using the 75 ohm setting, I tried the 300 ohm setting which works and seems to provide the same curve but I have to turn down the vertical resolution to fit it on the screen. For the earlier 41.25 Trap Alignment I connected the cable to the 3rd IF grid (test point G), set to 75 ohms and the B&K 415 output set to IF.



Zenith Service Manual Sweep and Marker generator circuit drawn below.



The directions note to use the above circuit on the first step which is 41.25 Trap Alignment, it does not mention it's use for the subsequent steps, either you don't need it or it is assumed you use for the remainder of the steps. Below is all that is said for connecting to the tuner. If the circuit is to be used the B&K 415 circuit is close, if you are not to use this circuit than the B&K 415 supplied cables are lacking as it did not come with a BNC pass through cable, which I hope means you don't need it.