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Mark, All of the electrolytics had been changed already.

First of all, I’d like to thank you for all your great ideas and suggestions: Mark, Barry, Tom, Pete, Eric, Raymond, and all those that I probably unintentionally forgot to mention. I went back to

Stephen, The low value electrolytics in the supply and signal circuits are likely bad. Ones made in the late 60's to early 70's that are axial with a clear jacket, usually Sprague, are commonly bad by

Hi all, As mentioned by Dave, fixing something is better then tossing and buying again. It's also good practice for us problem solvers! On the issue of broken interlocks the wife here used to slam the

I figured out how to get to the broken parts and here are some pictures: /g/TekScopes/album?id=270912 It turns out that the front part of the drum cam was indeed glued to the drum

n4buq <n4buq@...> added the album 7B53N Rear Drum: Broken Rear Cam Drum --- The following photos have been uploaded to the 7B53N Rear Drum ( /g/TekScopes/album?id=270912 )

Thanks, Stephen. I hope you find what's giving you the domino effect with yours. Wish could offer some advice. Thanks, Barry - N4BUQ

I wouldn’t necessarily call that upside down — the plate is still more positive than the cathode. I’d call it level shifted... Cheers Tom Sent from my iThing, so please forgive brevity and typos

Not sure I follow what you're measuring, but from the schematic, what I see is this (on any of EL84/7189A tubes): All voltages wrt Ground. Pin 3, cathode, -145V. Pin 2, control grid, -151V. Pin 6 or

Thanks, Ben.? I will see what I can do to get the interlock assembly.? Merry Christmas and Happy New Year to you and yours!? ? ?Jim?Sent from my Verizon, Samsung Galaxy smartphone

Looks like you made some headway while I was writing my post. It still might be worthwhile to do the connection tests with the plastic probe just in case you shake/bump the chassis and the problems

Thought I would give you some alternative ideas since traditional troubleshooting is not leading you to a result. There are a lot of directions you could take at this point and possibly it could be a

Happy for you. Congratulations.

Just checked the plates of the EL84’s… 0V and -6V after the 33ohm screen grid resistors…. Hmmmm

I think my 106 was simply angry with me for not cleaning it. Previous owner(s) had stored it in a fairly dirty environment (along with the 184 and 191 I got with it) and I hadn't gotten around to

BTW, I tested all the tubes, and they’re all reading strong and ok, no shorts. All filaments are lighting up just fine too. Don’t know what to think at this point…

Well, all the voyages are correct. And I used to have quite nice outputs on all outputs. Current limiting bulbs are not lighting up either. So I don’t think there is a shirt on the PT. Remember that

Correction: Power-rail short could certainly kill a single rectifier. But having multiple die so easily makes me think of the transformer. Pete

Perhaps an intermittent short in the primary side of the power transformer?? When the short kicks in, secondary-side voltages could go way higher than normal, frying lots of things. I can't think of

This all looks very much like a rather frequent problem with 465- and 475-scopes, which have similar construction. A lot has been written about this on this Group, including the tricky - but