voltcraft VC890 big current consumption 180mA - Page 1
Forum section: electronics / repair

author: MilanM
author_rank: Contributor
timestamp: December 25, 2019, 09:33:48 pm
content: Hello,I got one voltcraft VC890 its fully working except its current consumption is 180mA and it drain battery fast.When i bought it it had blown 3V voltage regulator and i replace it, it started working good except that issue with current consumption.I check the datashet for its main processor ES51997 and it says its maximum working voltage is 3.2V.I got slightly higher voltages for V+ and V-Like 3.22V for V+ and -3.57V for V-.Can some good soul help me figure out what is wrong with it.?If someone have same multimeter and can confirm voltage levels i would really appreciate that!In attached is a picture, and if someone can confirm voltages that would be cool!Thanks you very muchMilan

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 26, 2019, 09:45:52 am
content: I don't have the same meter so I can only give you general clues.Check for more damaged components around the 3.3V regulator you replaced.Start looking for a reverse polarity protection diode. 180mA should be giving off enough heat to actually be noticeable, still easier if you have access to a thermal camera.If supply to the ES51997 being too high is the problem (which I doubt is) the IC itself should feel warm.

author: MilanM
author_rank: Contributor
timestamp: December 26, 2019, 10:49:41 am
content: Hello, thank you for help.I check all parts around that burnt regulator, its all good now.There are few more regulators on PCB actually two of them labeled 9B59 and i cant find datasthet for them.Around one of them which is on bottom of the PCB is a bit of heating, its slightly heating but i cant tell exactly what it is as its on bottom of the board which is not accessible.Those two regulators gives output of 3.6V which is a problem i think as i expected like 3V out from them to supply main processor, as i mention it require max 3.2V.One of the regulator is for positive voltage and one of the regulator is for negative voltage as its converted over 7660 to -VIf anyone can tell what this regulator labeled 9B59 is, or if anyone can confirm voltage levels it would be awesome!Thermal camera will help a lot for sure.!I didnt notice heating on processor but for sure 180mA is a lot of current, fully working one should consume like 30mA, we have 6X more current here!Any suggestions are welcome!RegardsMilan

author: MilanM
author_rank: Contributor
timestamp: December 26, 2019, 11:01:08 am
content: Here is one printscreen from datashet of main processor, i believe my higher voltages causing higher current consumption as i am really close to the absolute maximum ratings.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 26, 2019, 01:48:37 pm
content: you may have some damaged tantalum caps ??

author: MilanM
author_rank: Contributor
timestamp: December 26, 2019, 04:42:53 pm
content: They seems to be good.I find out that voltage regulator is XC6209B362MR it can output max of 150mA of current.Normal current consumption is 30mA guess what 150 + 30 = 180mA looks like one of the regulators is working in like short circuit mode probably that's where the key is.I am wondering why they put 3.6V voltage regulators for supply when datashet says clearly maximum power for this chip is 3.2V