Picked up DM100C for $25 with leads and thermocouple and find it disappointing - I give it a fail.
Took it apart and there's a barnacle on the mA current shunt. Anyone else seen this? No need if you calibrate using EEPROM...
It's an added 68R 0805 parallel to the R56//R18 mA current shunt, goal seems to be 4.99R
100uA shunt is huge at 5k ohms, compared to 100R in AN8008.
100mA shunt is 5R.
600mA shunt 0.5R and the range is silly for a 10,000 count DMM. So 750mA reads as 00.75A on the next (10A) range.
10A shunt 0.05R with 10 second time limit for currents over 5A, according to the manual. There is only a 99.99A range (no 9.999A) i.e. you will read 01.17A instead of 1.169A like AN8008.
So some ranges are just oddball, and missing sig digits.
Continuity resolution is only 1
, there is no decimal point and the beeper is really slow.
DCV autoranging goes down to 1V scale, no 100mV unless you rotate to manual range.
The firmware is buggy and jack-detect expects you to turn the range knob, then connect jack in. If you are already in the right jack beforehand, it beeps, gotta pull it and put it back in. Now it's thankfully stopped working altogether except for the 10A jack, lol. There is no null/zero feature.
Inside is the familiar Dreamtech DTM0660L. "Smart double-core" seems to be just a COB LCD display processor.
The display is fast, overall the meter is just as fast as the AN8008 except for the beeper.
Creepage and clearance have several violations so it's not a 1,000V Cat. III 61010 puppy.
Current draw is about 26mA on 3V. LED backlight uses 3.3V boost converter. Reference is LM385-2.5V in SOT-23.
I did not peek at the serial data out or diassemble the EEPROM.
It's just a confused multimeter - has partial both auto and manual ranges.
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