Author Topic: Siglent SDM3045X mA current measurement - weird behaviour  (Read 1563 times)

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Offline tautech

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #50 on: November 13, 2018, 06:40:16 pm »

Do you still have this original rear panel 10A (not blown) fuse what was there installed at this time when internal 12A fuse blow.

Yes. I have checked it and it is indeed a 10A fast glass fuse
Can you please get the codes for the internal fuse ? .........I'll check my 3065X

See reply #45
« Last Edit: November 13, 2018, 07:10:22 pm by tautech »
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Offline rf-loop

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #51 on: November 13, 2018, 07:55:41 pm »

Do you still have this original rear panel 10A (not blown) fuse what was there installed at this time when internal 12A fuse blow.

Yes. I have checked it and it is indeed a 10A fast glass fuse

You have checked. How?
Do you  believe it is fast or do it have marking what it IS fast and how fast.
If there is mark for speed class, what it is. (ref Tautech next msgs)




If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline rf-loop

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #52 on: November 13, 2018, 08:04:13 pm »
SDM3065X
Rear panel fuse: 5x20 glass LF (Littlefuse) marking: 10AL250VP  As per datasheet spec this should be FB fuse.
Internal PCB fuse: Later when more time available............ but already we know it's ceramic.

"10AL250VP"

Is it possible there is installed wrong fuses?
(Need ask because China and fuses - I do not wonder anything. I have seen there with my own eyes so much...)

Where is speed identifier? It need be before current.

Here is Littelfuse 5x20 cap marking

Littelfuse product catalog and design guide, small fuse "bible"
Rear panel fuse # corrected, it does indeed have T but maybe F or FF would be best.

Rear panel fuse really have speed class marking T ?

Oh what a total mess.

Normally T = Slow Acting (Trage)

Not TT, not T, not M.... Only acceptable is F or FF and really from trusted manufacturer.
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline Qw3rtzuiop

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #53 on: November 13, 2018, 11:05:49 pm »
At my SDM3045X the internal Fuse is a ceramic LF T12AH250VP. The rear one is marked LF T10L250V.
 

Offline HKJ

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #54 on: Yesterday at 01:56:28 am »
I have just published a review of this meter: https://lygte-info.dk/review/DMMSiglent%20SDM3045X%20UK.html
Including a tear down.
 

Offline rf-loop

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #55 on: Yesterday at 06:10:16 pm »
At my SDM3045X the internal Fuse is a ceramic LF T12AH250VP. The rear one is marked LF T10L250V.

I think that reason why there was a T speed class 10A fuse, it need investigate and I believe it is now under investigation.
Personally, I also do not understand why a 10A fuse was used there. I think the fuse selection is doubtful. Including speed and its current rate.
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline nctnico

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Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #56 on: Yesterday at 06:15:04 pm »
If Siglent is smart they fit a 7A fuse and fix current sensing circuitry so it cannot be damaged before the fuse blows.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 


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