10L43 Predicta no hv

[DaveWM]

a few things that should be automatic

tube wiggle horz osc, horz out.
tube sub new horz osc, horz out.
voltage checks
resistance checks per chart in sams

voltage and resistance checks are just starting points to narrow down problems like the above mentioned open coils etc.

of course the K network could be the issue, but I prefer to not go there unless pretty sure its the problem, clearly a leaking coupling cap in the network that couples the plate to the grid would cause this problem, but I would scope it to be sure 1st before going thru the effort to make a new network.

one last thing, consider PCB issues, breaks in the traces are not uncommon esp around the horz out due to heat and movement from pulling stuck tubes.


the tube subs are important since they can and do go bad. If you want to check the horz out (no sub) then use the analyst to supple a good grid drive to it. this will clear that tube as the issue.

good point about the pot too, they should be checked (both the hold and range pot) for proper operation. I prefer an analog VOM for this to not only check for continuity but for smooth operation.