[...] UNI-T is certainly not the only manufacturer that changes the PCB of a product during its lifecycle, or that populates the PCB with different components from one production batch to another.
UT61E there are least 15 PC board revisions! Did you end up with the kindergarten or junior-high version? Earlier ones were extra junky and ended up in landfill.
It's a bit ridiculous and I don't get a sense they know what they are doing. Seem to sell prototype builds off with fake regulatory claims and as they learn, for years.
And it's over $0.25 worth of parts savings for the boss's new Lambo
The two schematics one has MOV's, they don't use Rev. #'s and SG4 (4th MOV) at the current-shunts, appears useless.
Rev. 13(GS) has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 12 has 4 MOV's, 3 PTC's, 600V fuses, rating Cat. III 300V, Cat. II 600V
Rev. 9C no MOV's, 3 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V; SOT89 clamps
Rev. 9A no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 8 no MOV's, 2 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V; SOT23 clamps
UT61E+
Rev. 3 has 3 MOV's, 4 PTC's, 250V fuses, rating Cat. III 1,000V, Cat. IV 600V
Rev. 2 looks the same, blue pcb