DT830B digital multimeter < merged >

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http://cgi.ebay.com/DIGITAL-MULTIMETER-Model-DT830B_W0QQitemZ260515743399QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7f2c6a7

I had 3 of these in the past years. I gave one away.
But the first one I used just a short time, and then the DC-voltage showed about 1,4 times (sqr(2)?) the real value. I easily bought a new one, because they have allways been rediculously cheap.
Recently the second one also got the same voltage error disease...

Does this sound familiar to some of you?
I opened both of them, but there is not much inside that looks reparable to me.
I like these multimeters because they are compact. May be someone has a repair solution?

< Merged the 2 topics - Plons >

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http://cgi.ebay.com/DIGITAL-MULTIMETER-Model-DT830B_W0QQitemZ260515743399QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7f2c6a7

I had 3 of these in the past years. I gave one away.
But the first one I used just a short time, and then the DC-voltage showed about 1,4 times (sqr(2)?) the real value. I easily bought a new one, because they have allways been rediculously cheap.
Recently the second one also got the same voltage error disease...

Does this sound familiar to some of you?
I opened both of them, but there is not much inside that looks reparable to me.
I like these multimeters because they are compact. May be someone has a repair solution?

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Buy a new one or buy a better one.

Stealing Proteus doesn't make you an engineer.

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ArnoldB wrote:
Buy a new one or buy a better one.

:) :lol:

Of course, you are right. But I cannot stand that such a simple thing is unreparable...
And I also want to mention that this product has the same defect twice at the same customer.

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Ok, then spend time repairing a 99 ct meter. To do so you'd probably need another meter. Get Intersil's datasheet for the IC and trace the schematic.

Stealing Proteus doesn't make you an engineer.

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STOP!! Double post.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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At those prices? Just chuck it and get another. Mine is pretty old, I think it came from Wal*Mart.

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

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Sorry John, it happened by accident.

On the other hand: there were 2 broken DVM's. So 1 post for each may indicate some intelligence of the forum machine.

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One of the eBay vendors for that model has a link in the listing to the "schematic". But the link is broken. That would be a hint, though, that the schematic might be floating about?

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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This seems to be the manufacturers web site..

http://www.e-sun.cn/EN/d.aspx?pht=303

Maybe you can email them and request a schematic?

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Yes alwelch, I also found that Sun probably is the manufacturer.

Also found the ICL7106 datasheet at Intersil, and before the rectifier circuit (example from Intersil datasheel ICL7106) is a C9014 transistor, not CA3140. New problem today is that I cannot repeat the problem: also the many years ago disposed one showed the correct DC reading this time. :?
I am surprised that this ICL7106 is still in use... Intersil must have made a fortune on that.
Anyway, the electronics inside have become clearer.

Thanks everybody for your contributions.

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alwelch wrote:
This seems to be the manufacturers web site..
Almost every Chinese multimeter manufacturer has one or more "830" multimeter on offer. I don't know if they have copied the design from each other, or if this is some standard Chinese (government) design.

Here is, for example, the schematic of one of Mastech's 830 versions http://www.radioradar.net/en/ser...

From a safety point of view these meters are anyway junk.

Stealing Proteus doesn't make you an engineer.

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These multimeters have rotary range selector,200mV,2000mV,20V,200V,1000V.If the measured voltage is higher than the selected range its impossible for this type of multimeters to have any kind of protection.And why should?
Also a poor contact of the rotary selector pressing the PCB could be the source of the problem.