This is a new-to-me scope. It has not worked correctly since I got it. When turning the time/div control, I can only get a trace on certain values - 20ms, 10ms, 0.2ms, and .1ms. On 50ms I can get a dot, but that is it. On most of the other time/div settings, I can get a dot when pressing the beam finder. The dot can be centered vertically but is always way off to the left horizontally, either at edge of screen or just off screen. It is same results for both channels 1 and 2, A and B traces.
I do have the service manual as well as the "troubleshooting your oscilloscope" guide but am getting confused where to start (other than checking power supply, which I did. Seems fine.)
Following the horizontal section troubleshooting, I got as far as the "armed" and "fired" events. In single sweep mode, it says to rotate trigger level fully clockwise, press the reset button, then rotate the level control counter-clockwise to its stop. When I start the CCW rotation, I get to about 2:00 when the trigger light flashes, a trace flashes across screen, and ready light goes out. The TDs are then low. Can't remember exact sequence, but I can sometimes get both the ready and trig lights to light at same time. (So "fired", I guess.) However, no trace visible. Can still get beam finder dot. Both TDs are high.
The troubleshooting guide doesn't really say what to check for the "start sweep gate" event.
From here, I am at a loss. Am I even in the right ballpark (circuit)? Any suggestions for what to test?
Disclaimer: I am very new to all this, so assume statements that might seem obvious to experts are not obvious to me. Bought the scope to learn how to test/repair things, not to learn how to repair it. I just figured if I can't diagnose/fix equipment with probably the best documented SM I will ever hope to see and biggest community of experts, then I have little hope of fixing other things.
Last comment: I do have another (working) scope to test with.