Ok, I will try my best with cleaning the socket. Here are some pictures of the aftermath: https://imgur.com/a/wIVfYYx The two capacitors near it don't seem to be in the worst health so I'm not sure wh

Well, unfortunately when I removed U550 and U570, I broke a leg off U570. Both are heavily corroded so I think I'll just replace both while I'm at it. The 7A12 manual lists both as replaceable by Fair

Actually I just found U550 next to U570 now, there's a lot of gunk covering the silk screen label and I didn't spot it when it was in the scope. This plugin is definitely the worst looking part of the

Huzzah, thanks Colin, I got it out. The thing is, I still had a lot of trouble even with your technique, so I tried it on my left timebase which is also missing the latch, and my right timebase withou

Here is the bottom of mine: https://imgur.com/a/B0FAYRI I'm not sure how to get to the spring or plastic without taking the whole bottom frame apart to remove the black guide rails. I can't access the

I attempted adjusting R551, however I reached its maximum and the 9V pin was at about 8.86V. I tried wiggling the board to make sure it was seated properly. The signal shown on the positive of both ch

Ok, last one hopefully. I went through the supply test points and found that the +9V pin is supplying 8V. This voltage is also on pin 13 of U225. The test point labeled inv is supplying the 0.13V, and

Addition: The measurements I linked were using channel 1. In channel 2 the voltage stays at about 0.13VDC in both positive and inverse settings. Shane

The behavior of the noise is as you describe it, at least in my testing. My 7A12 is actually missing the left cover, so I have access to U225 with it still in the scope. I measured (what I'm pretty su

Ok, thanks for the tip Harvey. Still having a bit of trouble with it, doesn't seem to want to budge. I'll keep at it. Also I didn't know there was supposed to be a bottom cover, haha. Apparently my sc

The vertical plugin I believe is a 7A12. I did check both channels and the variable buttons are pushed in. I could use them to temporarily calibrate the scope if I need to use it I suppose. When I put

The trace only gets fuzzy when I have the calibrator signal plugged in, and only the top half. The issue still comes and goes, usually after I change a setting, e.g. the vertical channel. With no sign

For clarity, the image I took was at the same intensity setting on the knob, but now that I just turned it on after sitting for a while, the issue with the brightness seems to have corrected itself. T

Ok, I think I'm almost there so hopefully I'll be out of your hair soon, haha. I got U4494 out and cleaned and reseated it. Then, with a liberal amount of wiggling, the logic board popped in place and

Sorry about how many replies I'm making. I also noticed the PCB U4494 sits on is quite severly bent, as seen in this album: https://imgur.com/a/fsQ1DrN I don't see anything shorted to the board behind

Ok, I did the swap myself and saw no change in the trace or readout behavior. I now have the power supply pulled out to get to U4494. Unfortunately it seems to be thoroughly stuck in the socket, and I

Ok, I appreciate it. I almost wonder if a connection got jostled when I took out the horizontal plugin and put it back in; that would line up with the logic board. Shane

Ok, I have the top rear cover off, it appears the leads would be long enough to swap J2203 and J2208. To clarify, you're suggesting I return R2135 to roughly its original position, turn on the scope,

I checked the +130 and -50V on the A20 horizontal amplifier, the -50, +5, -15, and +15 on the A19 vertical amplifier, and the +15, +5, and -15 on the A13 readout board going to the powered probe conne

I think the faint line between the peaks at the top is the flyback line (the trace intensity looks much higher in the image than it is in real life): https://imgur.com/a/KKS7vMp I've discovered neithe