I have this tek 465m for many years and it has always had the following problem.
There is no horizontal sweep (either A or B) when the "var" knob is in the calibrated position (i.e. uncal LED off). other than that the scope works really well and other than being an annoyance it hasn't bothered much.
However, last week last week the high voltage supply when out (the fuse blew) and after fixing that, I wanted to dig into the horizontal problem. I don't think the HV problem and the clibration problem are related at all.
What I have found is this.... the switch and variable pot are OK. There are two switch circuits, one shorts the variable potentiometer wipe to the low contact and the other switche the uncalibrate LED. Just shorting the wiper on the potentiometer using a jumper wire, while the variable pot is at 25% will "calibrate" the sweep timing. It turns out that the sweep will only work when the LED is "on". There are three LEDs which are driven off the same power supply, which look like they are derived from the +32V using a voltage divider, trigger, MAG10 and the Uncalibrate LED. It turns out that if either of the MAG10 or the Uncalibrate LEDs are on, the sweep will work. There is a small dip in the LED power supply rail (5mV) when either these LED are on. I suspect that this also effects something in the sweep generator.
Has anyone run into this ? I do have a maintenance manual. Unfortunately, this manual does not have the foldout schematics and the simplified schematics aren't relevent. Anyone know were I can get a copy of the schematics for the relevent sections (i.e. sweep, LEDs, etc...).
Thanks, -ingo