Hi, all,
I have kind of a strange annoyance that I have never seen before. It's on my Leader model 1021, 20MHz oscilloscope. I am looking at diode curves on X-Y mode, feeding 60Hz from a small step down transformer (about 2 VAC to 6 VAC) through a series 10K to 47K resistor and then the diode. One probe goes across the diode to give scope deflection for the voltage across it, and the other probe goes across the series resistor for current deflection. The probe grounds are common in the center (hooked together) so there is no short.
Anyway, I have done this many times on different oscilloscopes and it works well, but just on the Leader scope, I center the trace dot with no (60Hz) signal, and get my curve, but it slowly drifts across the screen from left to right. I tried both AC and DC coupling and it makes no difference. I see nothing in the scope's service manual to adjust for it.
Anybody got any ideas? It's really annoying.
Thanks!
Rob
I have kind of a strange annoyance that I have never seen before. It's on my Leader model 1021, 20MHz oscilloscope. I am looking at diode curves on X-Y mode, feeding 60Hz from a small step down transformer (about 2 VAC to 6 VAC) through a series 10K to 47K resistor and then the diode. One probe goes across the diode to give scope deflection for the voltage across it, and the other probe goes across the series resistor for current deflection. The probe grounds are common in the center (hooked together) so there is no short.
Anyway, I have done this many times on different oscilloscopes and it works well, but just on the Leader scope, I center the trace dot with no (60Hz) signal, and get my curve, but it slowly drifts across the screen from left to right. I tried both AC and DC coupling and it makes no difference. I see nothing in the scope's service manual to adjust for it.
Anybody got any ideas? It's really annoying.
Thanks!
Rob
Does the dot drift with no probes attached and the input coupling switches set to 'ground' ?
To a greater or lesser extent (it should never move all that much), this is fairly common and comes down to the circuit design of the scope and poor thermal drift of the input stages. If its drifting half way across the screen then something is amiss.
To a greater or lesser extent (it should never move all that much), this is fairly common and comes down to the circuit design of the scope and poor thermal drift of the input stages. If its drifting half way across the screen then something is amiss.
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