I'm designing an H bridge driver in LTSpice 17.0.19.0. The bridge is working very well, but LT refuses to bring up the current meter or thermometer icons for just two components in the entire circuit, the transistors in the upper left quadrant. The quadrant must be delivering current, since the load current and waveform are as expected.
I've tried deleting and reinstalling the components, which didn't help. I don't understand LT internals well enough to even hypothesize problems and solutions.

Hoping this is a known bug. It's not holding me up just now, and if needed I can put in 1 milliohm resistors to check branch current. But it is a worry. What other surprises might LT have in store for this circuit? This must be my twentieth design at least, and this is the first time I've seen this.

I meant to add, I've completely isolated the quadrant from the rest of the circuit and tested it on its own load. It is identical to the upper right quadrant, which has no problem.

Update: I've f6 copied the entire schematic into a new blank document. This copy shows current and temp for one of the two affected transistors. Tried copying the copy into yet another blank document, with no improvement. Seems LT glitched something in the original file, but how did copying do a partial fix?

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We can't help much unless you let us see more of what you are doing. Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files,? in a ZIP archive to Files => Temp, and then tell us you did that.

Update: I've f6 copied the entire schematic into a new blank document. This copy shows current and temp for one of the two affected transistors. Tried copying the copy into yet another blank document, with no improvement. Seems LT glitched something in the original file, but how did copying do a partial fix?

dcorner1953 wrote, "LT refuses to bring up the current meter or thermometer icons for just two components in the entire circuit"

Just to be clear, transistors have 3+ terminals, so the currents you're talking about are their pin currents.? You can't measure (plot) the current on a transistor, but you can plot the current into each pin.? Make sure to position the pointer on the wire going to that pin, otherwise the current meter won't appear.

If the transistor model is a .SUBCKT model, you should enable saving subcircuit currents.? That setting is in the Control Panel, Save Defaults tab.? Also, if you used a .SAVE or .PLOT or .PRINT command anywhere on your schematic, those commands limit what voltages and currents are saved, so don't use them unless you really need them.

It is not a known bug.? Certainly nothing that affects transistors in the upper left quadrant of your schematic -- or the upper left I/V quadrant -- or the upper left quadrant of the bridge -- or whatever else you meant.

? ? "What other surprises might LT have in store for this circuit?"

Well, for one thing, the values you used for R34 and L2 are ridiculous, so don't use those!? Also, your 2N3055 might need to be reconsidered.? And don't use a 1N34 as the power rectifiers!? You knew that, right?

? ? "Seems LT glitched something in the original file, but how did copying do a partial fix?"

Isn't it obvious?? When you did that copy, the moon eclipsed Mercury and that rearranged all the charm quarks in the copied version.? I could tell by looking at your schematic, it was as plain as day.

:-)

Now where did you put that schematic?? Oh, wait, you didn't!? I guess my mind-reading skills need a little work.

Stop trying to make us guess what's in your schematic.? Upload it.

Andy

Will do. Just thought I'd check to see if it's a known bug before assembling the stuff.