Now I have nice sharp trace and working intensity control!
Good progress.
Horizontal A sweep
The 5 2 and 1nS settings are not working at all.
485 uses B sweep generator for 5/2/1ns settings even in A sweep setting. Since you are seeing functional 5/2/1ns in B sweep it is a problem of scope not selecting B sweep in 5/2/1ns settings as it should. In those settings do you see B sweep ramp (while you are in A sweep setting on the knob) at collector of Q1236 of sheet <9>? What is the voltage at pin N1 sheet <12> when you are in 5/2/1ns settings (0.6V expected) vs above 5ns setting (-0.5V expected)?
I don't get any B sweep from 5s to 20ms then I get good B sweep for 10mS to
0.2uS
0.1uS to 10nS is showing only first 4 divisions from the left
Probably next step of debug.
5 2 and 1 ns is working correctly.
See above. A sweep uses B sweep generator for 5/2/1ns.
Power supply fan.
Is quite picky, it sometimes runs and sometimes it does not.
Siggi's link is great. The other thing to check is if you give it a gentle push if it starts rotating. The fan speed is temperature controlled, C1482 looks like it is placed there to give an initial kick. You may want to replace C1482 to see if it makes any difference.
Ozan
