721-TS Problems

[bgadow]

I've been studying this in depth, trying to learn something. My "progress" so far:
I paralleled the low voltage caps. The 2-470mfd @50v caps are doing fine but the pair of 100 @ 50v got very hot. Well, when faced with brute force I offer brute force right back! In went a pair of 100 @ 450v! Take THAT! I also found that the vert centering control had been cooked at some point so in went another pair of wirerounds for now. At this point nothing is cooking so I can take my time trying to diagnose the lack of vertical sweep.

I undid the vert osc xsfmr leads and I measure 182 ohms/1500 ohms. Sams sez 165/1310, so I guess thats close enough. No reading across the two. The grid of the vert osc. shows nothing; there is a .0047 cap to the xsfmr and the xsfmr side reads 95vdc. The grid also goes through a 1 meg resistor to the vert hold-95vdc also on the wiper there. Wiper of the height control shows about 400v. Tried jumpering the resistors in the circuit. Putting ac (cap from filament) gets sweep on both osc. and output grids. With a lousy antenna hooked up I even got video-good enough to tell the guy was playing golf! Now, if it sounds the least bit like I know what I'm doing, don't give me that much credit! I'm trying though. To show how I think, looking at the Sams I see that the osc grid should show -6vdc so I tried hooking in a 6v lantern battery to see what would happen. Well, the sweep expands, but just for a flash.

At this point I guess either the xsfmr really is dead-any way to tell short of substitution? or there is something else I'm overlooking. I'll keep at it, any ideas welcome.