| Products > Test Equipment |
| Dangerous APPA DC mV bug or just a glitch? |
| (1/1) |
| Bobson:
Playing with new PSU I ran across strange behavior of an APPA 109N DMM. While measuring 19V DC output of PSU, I switched DMMs rotary to mV range to see AC byproduct (I know it would be wrong with DC offset so high, but intended to drop voltage after) and mistakenly pressed MODE (AC->DC->AC+DC) button instead of LIGHT. I was really astonished that in DC mV mode my venerable APPA 109N gave me several mVs instead of OL. When I dropped voltage down to several volts, it started displaying OL. I repeated it several times, and it was not a temporary glitch, always repeating. Disappointed, I repeated the sequence with rather similar model, APPA 305. It has DC mode default in V and mV ranges, but results were the same. APPA 506 has separate DC and AC Volts and millivolts, and has NO glitch. I wonder if this bug-or-feature present on another APPA models, including 10x series and 20x series? (208 is actually benchtop version of 506, while 201-207 are benchtop versions of an older 300 series). Attached photos show 3 DMMs in DC V mode, 2 APPAs in dc mV mode, all three in DC mV mode. U1252A used as a ref. |
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