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Author Topic: Chip identification, Voltcraft vc 890  (Read 2238 times)

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Offline EinRainerZufallTopic starter

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Chip identification, Voltcraft vc 890
« on: January 11, 2020, 10:31:09 pm »
Hello, I bought a cheap defective Voltcraft vc890, but unfortunately cannot find out the names of the defective components. If someone can help me who has this DMM or takes good pictures, I'm very grateful to them.
Q1 and Q6 are the broken ones.
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Offline fzabkar

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Re: Chip identification, Voltcraft vc 890
« Reply #1 on: January 11, 2020, 10:59:05 pm »
Q1 looks more like an LDO linear regulator than a BJT or MOSFET, otherwise I can't understand the purpose of C28.
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #2 on: January 12, 2020, 02:15:57 pm »
i found out that Q6 is labeled with A4 and is a BAV70W or something similar is. And Q1 i cant read well but on it stant A183A or A1B3A but unfortunately i can't find none of this.
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Offline fzabkar

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Re: Chip identification, Voltcraft vc 890
« Reply #3 on: January 12, 2020, 08:16:14 pm »
The ES51997 IC requires a 3V supply. You might like to trace its supply pin back to Q1 to test whether Q1 is a 3V regulator.
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #4 on: January 12, 2020, 10:18:53 pm »
Good idea and yes after i traced it out it is the 3v regulator. The next is with how much output current i should calculate ? The package is SOT89
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Offline fzabkar

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Re: Chip identification, Voltcraft vc 890
« Reply #5 on: January 13, 2020, 01:49:41 am »
Page 5 of the datasheet specifies 3.2mA as the maximum operating current in DCV mode.

http://www.cyrustek.com.tw/spec/ES51997.pdf

Have you determined the pinout?
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Offline wraper

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Re: Chip identification, Voltcraft vc 890
« Reply #6 on: January 13, 2020, 02:04:48 am »
Quote from: fzabkar on January 11, 2020, 10:59:05 pm
Q1 looks more like an LDO linear regulator than a BJT or MOSFET, otherwise I can't understand the purpose of C28.
Disconnecting power.
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Offline ebclr

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Re: Chip identification, Voltcraft vc 890
« Reply #7 on: January 13, 2020, 08:01:19 am »
A4 Mark is BAV70
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #8 on: January 15, 2020, 12:28:53 am »
Sorry for the late post, I had a lot to do. I found out the pinout.
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Offline fzabkar

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Re: Chip identification, Voltcraft vc 890
« Reply #9 on: January 17, 2020, 12:51:37 am »
I'm wondering, would it be safe to test the unit with a 3V lithium coin cell?
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #10 on: January 18, 2020, 03:10:21 pm »
At the moment i haven't a 3V lithium coin cell but i powered the meter with my lab supply and on 3.3V it goes on and draw around 50 mA. Do you think i can replaece it with this from Mouser ?
https://www.mouser.de/ProductDetail/ABLIC/S-812C33AUA-C2NT2G?qs=%2Fha2pyFaduhHm29h3nOKRaOvQ7dXk97IvZXrSBdi%2F6D2yC%252BLFVwsLA%3D%3D
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Offline fzabkar

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Re: Chip identification, Voltcraft vc 890
« Reply #11 on: January 18, 2020, 09:04:16 pm »
It's a 3.3V regulator rather than 3.0V. I don't know whether that's OK, or whether it affects the calibration. ???
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #12 on: January 19, 2020, 12:49:45 pm »
Quote from: fzabkar on January 18, 2020, 09:04:16 pm
It's a 3.3V regulator rather than 3.0V. I don't know whether that's OK, or whether it affects the calibration. ???
What do you mean ? The part that i linked is a 3.3v regulator.
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Offline MilanM

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Re: Chip identification, Voltcraft vc 890
« Reply #13 on: February 04, 2020, 10:34:51 pm »
Hello
I had similar situation.
Here is my topic https://eevblog.com/forum/repair/voltcraft-vc890-big-current-consumption-180ma/

Well regulator is used to supply g230f128 and its 3.3V regulator.
If its dead it probably damaged controller as it was in my case, after replacement current consumption was like 180mA and it drain battery in like one hour which made multimeter useless.
« Last Edit: February 04, 2020, 10:39:49 pm by MilanM »
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Offline EinRainerZufallTopic starter

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Re: Chip identification, Voltcraft vc 890
« Reply #14 on: February 04, 2020, 11:17:33 pm »
Quote from: MilanM on February 04, 2020, 10:34:51 pm
Hello
I had similar situation.
Here is my topic https://eevblog.com/forum/repair/voltcraft-vc890-big-current-consumption-180ma/

Well regulator is used to supply g230f128 and its 3.3V regulator.
If its dead it probably damaged controller as it was in my case, after replacement current consumption was like 180mA and it drain battery in like one hour which made multimeter useless.

I replaced the 3.3V regulator and jet the multimeter work perfekt and the current consumption is 40mA.
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Offline MilanM

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Re: Chip identification, Voltcraft vc 890
« Reply #15 on: February 04, 2020, 11:29:54 pm »
Yes 40mA is normal current consumption! Congrats you got it working! :)
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