While measuring ripple on a 600v power supply, with the channel input set to AC and 100:1, there's a DC offset. I'm using an after market (TPI), 100:1 probe. I'm not getting the offset at 300 volts using the Agilent or the TPI probe. When I connect the TPI probe to my old "Tek" analog scope, there's no offset at 600v. To me it appears that there's a leaky coupling capacitor on the vertical input. Is there something wrong with my 3024? Is this something I should be concerned with?
I've got the same scope (msox3024a) and I am having trouble with triggering on _any_ ac signal riding on a DC voltage (power supply hum) when the channel is DC coupled. Is this something you have noticed too?
So much of the time, my scope is stuck in "Trig'd?" with either no signal displayed or a 'flatline' ... when the probe is connected to +200VDC with a hefty AC signal on top of it (which to me is a bit of a safety concern!). The scope _absolutely must_ display a signal, even if it's the over-driven input if it is connected to a high voltage.
Though I've had some success triggering with bandwidth limiting and the noise rejection in trigger mode menu, but it begs the question of what signals are not being displayed to achieve this trigger.
As for the DC offset you're seeing, is it a second low frequency wave that is simply triggering at a positive crest?
In other words, with no word of support from Agilent, you should be concerned.
Regards, Phil