| Electronics > Beginners |
| The horizontal line on oscilloscope display |
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| james_s:
There is no particular circuit block that delivers a flat line, the flat line is caused by the absence of vertical deflection, the horizontal deflection sweeps the beam across the screen, voltage at the probe causes the beam to move up for positive voltage and down for negative voltage, if the voltage is zero then the beam will sweep across the middle of the display. Note that this describes how an analog scope works, if you have a digital scope then it will tend to approximate this behavior but they don't work quite the same way. Either way I'm not at all convinced that there is anything wrong with your scope, can you post a video of what it is doing? |
| StillTrying:
"What circuit block is usually responsible to provide a flat line to the crt when there is no signal input or coupling is on ground?" AUTO trig! If there's been no real triggers for around 0.8 sec AUTO trig should start unsynchronized triggering. It might be the mechanical switch. Then it's time to study the schematic, trigger -> timebase. |
| gkmaia:
--- Quote from: StillTrying on April 21, 2019, 12:42:09 am ---"What circuit block is usually responsible to provide a flat line to the crt when there is no signal input or coupling is on ground?" AUTO trig! If there's been no real triggers for around 0.8 sec AUTO trig should start unsynchronized triggering. It might be the mechanical switch. Then it's time to study the schematic, trigger -> timebase. --- End quote --- Thanks. That makes sense. I have an issue with intensity circuit that is flat at a node that should be oscilating. Also the blanking is not a 100% as i see a faint line conecting the ends of the signal as it sweep back. They all share the same board as the trigger. But the trigger is fine so far. I will investigate more. |
| Tom45:
As many have said, what you are reporting is to be expected if the trigger mode is in normal mode. If trigger mode is set to auto, you should see a line. However, you haven't said if you have tried setting the trigger mode to auto. Also, what scope do you have? |
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