Usually I will use an ordinary 5% or 2% resistor externally. Haven't had to repair a meter since I started doing this about 20 years ago.

Likewise. But I invested in a couple of resistors: 1 ohm and 1 kilo ohm. Both 2W, 1%.
The voltage reading of the first is directly amps, the second, milliamps.

 

Those can be useful for a long time, checking out projects.

 

Thank you everyone, so many folks eager to assist, it is appreciated. My original question was: is it normal for an op amp in a simple config to

What package are your TL072 op-amps in?

These are DIP-8 in 'round hole' machined sockets.

 

Thank you everyone, so many folks eager to assist, it is appreciated. My original question was: is it normal for an op amp (TL072, SA5532, or LM833 all tested) in a relatively simple config (buffer, or ~2x inverting gain) to get hot (150F+). Looks like the answer is no. Also thank you Dennis for breaking it down via the thermal specs from the data sheet. Also thanks everyone for the suggestions on what to check.

Not to derail my own thread by diving into the cause (I was not yet trying to get to a cause, just trying to understand if it was normal or not, I am grateful for all of the suggestions to find the cause! ), but it would appear that flux and/or long wires may have contributed, even with my capacitors. I unhooked it all, thoroughly cleaned the flux off the board as best I could, re-connected with much shorter wiring for power and signal, now they run much cooler, looking at about 100F for the TL072s.

Perhaps it was flux, as well as maybe some high frequency noise from the long power and signal wires. As stated, I did not see any obvious wave deformations on the oscilloscope (1Khz sine source), which tells me they were outputting the desired signals. That doesn't mean there weren't also some small amount of tiny high frequency noise hiding in there.. Maybe they were working overtime to buffer/amplify something really HF/noisy? I do have a new RF analyzer I could also bring online - after I figure out how to operate it, and after I understand what I am looking for.

To answer some questions: new, name brand chips from Mouser (not knock offs, and not old played-with chips); ambient room temp of 70F, not in backwards (they were in fact amplifying and buffering as expected), temperatures observed with a FLIR One pointed at the chips, then confirmed with a laser thermometer pointing at the chips, a fingertip that didn't want to stay on the chips, and a nose that said "something smells kinda warm, is this normal?". Unfortunately I didn't check the amperage consumed before the rework.

I do have a much bigger circuit with numerous hot op amps (150F+), in several more configurations (filters, mixers, choppers, oscillators, waveshapers) but I don't know if it would be appropriate to start a thread to ask folks to help me debug that large circuit. It's probably more flux or HF noise... thank you everyone!

 

Is it possible that there is an oscillation in the megahertz range that does not show up on your scope?? devices running that much hotter does not make sense.
Andjust because we have not discovered the reason does not mean that there is not a reason.

 

A TL074 op-amp will only feel warm, not hot, in normal, no-load operation, consuming a typical quiescent supply current of 2.5 mA. This results in very low power consumption, only a few milliwatts of heat, as it only dissipates the power from this current draw and not from driving a significant load. If it feels hot, there's likely a wiring error, an overloaded output, or a short circuit.