EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: MilanM on December 25, 2019, 09:33:48 pm
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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 much
Milan
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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.
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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 -V
If 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!
Regards
Milan
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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.
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you may have some damaged tantalum caps ??
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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