Hi all,
Some of you will be aware I was trying to find the source of the YTO unlock error I was getting displayed on the screen of my 8566B. I'd been advised elsewhere to scope the power rails for any signs of instability and at that time, aside from some small variations in the expected voltage levels, all seemed fine. However, I wasn't happy I'd got the right scope for the job and the optimum settings for this kind of check, so I've had another try and discovered something seriously amiss. There is some small level of noise on the DC rails, but no more than I would expect from looking at *any* power rail. The issue that jumped out this time (having got the right tool for the job; setting right etc.) is the presence of persistent, random, voltage spikes. The excursions from the DC value go at least 60mV plus and minus from the DC value. They're really skinny if that's any clue; so narrow they're sometimes hard to see. But they ARE there nevertheless. I have two questions here:
1. Could these spikes cause the YTO unlock condition?
2. What could cause these spikes, given that they're present on ALL the DC rails: -40V, -12V, -5.2V, +5.2, +12V, +22V and so on?
I'm pretty sure this isn't operator-induced error, but I guess I can't altogether rule out the vague possibility it may be an internal fault in the oscilloscope itself. But let's assume for now the spikes do not originate within the 'scope itself.
Thanks.
Jinxie