Here's a little "general-purpose tip" for Pico users. I've got a 4423 scope, & while it's really nice to have 4 channels when needed, most often I'm using 2 (typically Volts & Amps on whatever I'm testing). More often than I care to admit, I grab my scope, hang it up (I made a protective sleeve with hook), hook up my leads, & stare at flat lines on my laptop screen. I recheck my connections- still no change.  >:(

After cursing & grumbling awhile I LOOK at my leads- hard, then curse some more, slap myself on the head (Gibbs-style  ) & move my leads from jacks D - C (CH4 & 3)  to jacks A - B where I get now get a pattern :-[. I tried putting a BIG letter A on the scope sleeve by that jack, added bright orange paint there as well. No good.

I can't tell if I just "can't help myself" or if I'm "beyond all help"  ::).

I did come up with a solution that works. I took a piece of soft/clear PCV hose (about 3/8" ID-thinwall) & cut it to 1/2" long. I then drilled two small holes 180* apart about 1/8" from one end to fit over the lugs on a BNC jack. Put a little dielectric grease on the inside of the hose & I can "pop" the hose over the jack for CH4 to remind me where NOT to hook up. It easily comes off if I do need CH4.

Not sure what problem you are trying to solve there.  You can use any combination of channels you want.  Maybe I misunderstand....

Tom: I think he's just starting at one end of the scope, and if it's upside down a accidently hooks up to the channel D and C inputs instead of A and B, then sees nohin' on the screen. A dummy cap on channel D BNC makes which end to use easier. -Ward-

Oh, Thanks Ward.  I get it now....Channel A and B turned on channels C and D off....test leads on C and D only. 

Quote:

A dummy cap on channel D BNC makes which end to use easier.

Exactly. I put a hook on my scope to hang it from the car's hood  to keep it out harm's way while I'm using it- when the BNC ports are pointing down there's no "rightside up".

Eh, if it needs alot of explaining, I guess it must not be much of a problem for most folks.