Brymen BM869s says 'DiSC'  when measuring capacity - Page 1
Forum section: electronics / testgear

author: Swake
author_rank: Frequent Contributor
timestamp: January 14, 2023, 08:10:02 pm
content: Hi,I tried confirming a 100µF/35V electrolytic cap was still good with the BM869s today. After some range switching it briefly showed the letters 'DiSC' on the display and then showed the measurement.On shorting the leads it does the same thing.What does that DiSC message mean? I couldn't find anything about it in the manual, or I overlooked it.Notes:- The cap was discharged and it measures fine and was confirmed fine on 2 other meters. The Brymen has the same behavior with some other caps.- The Brymen is very slow at reading capacity compared to my Fluke 289. The Brymen is not a speed monster in general, but for capacity it is actually annoyingly slow. I even wonder if it is normal.

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 14, 2023, 08:45:43 pm
content: Discharge or Discharging.Frank

author: Swake
author_rank: Frequent Contributor
timestamp: January 16, 2023, 12:21:01 pm
content: Discharge came to my mind too but I cannot place it. I always make certain to test discharged caps prior measuring.The message shows up after the Brymen has already switched several ranges and it switches again after the message and then only shows the measurementIt also shows up when the test leads of the Brymen are shorted without DUT in between, there is nothing to discharge.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 16, 2023, 01:39:02 pm
content: Seems not unusual, see this:Although the comment says it does not happen when you discharge the cap yourself first.

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 16, 2023, 03:35:13 pm
content: I didn't find any hint in the manuals (869 + 869S), so let me speculate about this 'DiSC' display.DMMs usually use a timed charging method, C ~ dt/dU, i.e. the capacitor will be charged from zero and the time needed for reaching a certain threshold voltage.This is done repeatedly, i.e. the capacitor is automatically discharged (w/o displaying that phase).If you change the range, though, this next range might detect the residual charge from the other range, and needs to discharge for a prolonged time, like in the case of a still charged capacitor.That might be the root cause.. maybe you contact Brymen directly, what's about 'DiSC', they are very cooperative.Frank

author: AVGresponding
author_rank: Super Contributor
timestamp: January 16, 2023, 06:30:04 pm
content: Mine will do it if you short the leads together, and sometimes momentarily while ranging up.

author: 807
author_rank: Frequent Contributor
timestamp: January 17, 2023, 12:41:54 pm
content: Quote from: Swake on January 14, 2023, 08:10:02 pmMine does exactly the same when in autorange mode. Doesn't do it when set to uF manual range though (and reads much quicker too).Edit...just noticed that a 100uF capacitor reads zero when on the 0.000 mF range. It should read 0.1 surely?To make sure the meter was working on the mF range, I tried a 1000uF cap. That measured OK.

author: mwb1100
author_rank: Frequent Contributor
timestamp: January 17, 2023, 05:56:07 pm
content: Quote from: 807 on January 17, 2023, 12:41:54 pmThe BM869s specs on capacitance says (BM869s manual):QuoteSo in the 5.000mF range, the accuracy for 0.100mF is "unspecified"

author: 807
author_rank: Frequent Contributor
timestamp: January 18, 2023, 01:00:52 pm
content: Quote from: mwb1100 on January 17, 2023, 05:56:07 pmThanks. That's very odd behaviour though. I tried different capacitor combinations. The meter reads nothing at all up to 162uF. At 171uF I got a reading. So the crossover point was somewhere between the 2. Never known a meter to behave like that before.My ISO-TECH 305 reads all values on the 0.000mF range.

author: 807
author_rank: Frequent Contributor
timestamp: January 18, 2023, 02:38:07 pm
content: It's strange that while playing with capacitors on the iso-tech, I noticed how fast it was on the auto range setting compared to the painfully slow Brymen. This is the opposite to measuring resistors, where the Brymen beats the iso-tech.https://www.dropbox.com/s/7575imy8w3i5vky/ISO-TECH%20305%20auto%20capacitor.mp4?dl=0