RCA 621ts Restoration

[old_coot88]

Originally Posted by vts1134

...I recently acquired a B&K 1077 so I can show what a regular picture looks like now. I had prevously thought that the vertical was running too slowly but you can see now that is not the case. The horizontal white bands do not roll with this signal, instead they are steady right where you see them.

It sure looks like a huge power supply ripple. The bars not rolling would be the case if the B&K's vert sweep is locked to the powerline (whereas a TV station's vert is offset slightly, which would cause the bars to roll). Possibly one of the replacement filters has gone open.

If you've got an extra 'lytic cap of equivalent rating as the main filters, you can jumper each one and see if the ripple disappears.

Or alternately if you have an analog AC voltmeter, you can measure ripple. Just put a cap of .1mf or so in series with the meter's hot lead (to block the DC component). I'm not sure i would trust a digital meter in that application.