The surge resistor and PTC are still used in the voltage range to clamp via the two series MOVs to ground.
No argument.
What if the PTC heats up? Now the MOVs aren't doing much.
Sure they do. They continue to clamp the voltage and provide the majority of the return path. Now if you select one of the functions that engages the low voltage clamps, then the MOVs are basically removed.
My only point was that many meters have a path from the input jack to the IC that doesn't go via the PTC as shown in your input protection video.
Actually your original comments were quite clear:
The PTCs aren't on the "voltage measurement" part of a multimeter circuit, they're on the much lower-impedance "ohms/continuity/etc" part of the circuit.
I haven't looked closely at this particular Uni-T but generally multimeters have a separate 10MOhm voltage input and a 10kOhm+PTC resistance/continuity input.
You offered the Fluke 101 as an example and I suggested you actually test it by removing the PTC from the circuit and reporting your findings:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg3717439/#msg3717439With you now back-pedaling on your original statements and suggesting your point was something completely different I am curious:
A) You removed the PTC and found the 101 could no longer read AC and/or DC voltages?
B) You removed the PTC and found the 101 could still read AC and/or DC voltages but you don't want me to eat too much crow?
C) You want to continue to believe your original statements and are concerned they are wrong? (burying your head in the sand rather than confronting it)
D) You lack the soldering skills to lift one pin or the 101 costs too much and you are concerned about damaging it?
E) You're too lazy and can't be bothered to test your theory?