Powering a chassis with tube/yoke off.

[Daave]

I did post this in my other thread, but not sure anyone is reading it anymore, so this is sorta a double post.

I have the chassis on the bench and was wondering how to power it up with no anode connected or yoke connected. Can this be done?

I wanted to take a poke around at b+ voltages and other readings as well as learn to take readings with this oscilloscope I picked up, and compare to the schematic.

On another note the schematic contains many scope images but not really clear on when to take them (signal applied?).. I was going to try to figure out how to inject a composite signal into the TV to figure out why it wouldn't tune a colour picture.

Any info is great! Thanks!

[miniman82]

Remove the horizontal output tube and vertical output tube, then look in the schematic to see if the yoke has a jumper. If it has a jumper, it has to be connected or the chassis will either not work or only certain sections will work (depends how it's wired).

[Steve McVoy]

Operating a set without the yoke won't allow you to look at the waveforms in many cases. The yoke is needed to provide boost voltage, which is often used to power many circuits. Also, many sets use a pulse from the flyback to key the AGC.

A better approach is to use an extension cable for the yoke, or to remove the yoke from the CRT.