Author Topic: Siglent SDM3045X mA current measurement - weird behaviour  (Read 12258 times)

0 Members and 1 Guest are viewing this topic.

Online tautech

  • Super Contributor
  • ***
  • Posts: 29810
  • Country: nz
  • Taupaki Technologies Ltd. Siglent Distributor NZ.
    • Taupaki Technologies Ltd.
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #50 on: November 13, 2018, 07:40:16 am »

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, 08:10:22 am by tautech »
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
 

Offline rf-loop

  • Super Contributor
  • ***
  • Posts: 4135
  • Country: cn
  • Born in Finland with DLL21 in hand
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #51 on: November 13, 2018, 08:55:41 am »

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)




EV of course. Cars with smoke exhaust pipes - go to museum.
Wises must compel the mad barbarians to stop their crimes against humanity. Where have the (strong)wises gone?
 

Offline rf-loop

  • Super Contributor
  • ***
  • Posts: 4135
  • Country: cn
  • Born in Finland with DLL21 in hand
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #52 on: November 13, 2018, 09:04:13 am »
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.
EV of course. Cars with smoke exhaust pipes - go to museum.
Wises must compel the mad barbarians to stop their crimes against humanity. Where have the (strong)wises gone?
 

Offline Qw3rtzuiop

  • Regular Contributor
  • *
  • Posts: 239
  • Country: de
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #53 on: November 13, 2018, 12:05:49 pm »
At my SDM3045X the internal Fuse is a ceramic LF T12AH250VP. The rear one is marked LF T10L250V.
 

Offline HKJ

  • Super Contributor
  • ***
  • Posts: 3086
  • Country: dk
    • Tests
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #54 on: November 13, 2018, 02:56:28 pm »
I have just published a review of this meter: https://lygte-info.dk/review/DMMSiglent%20SDM3045X%20UK.html
Including a tear down.
 
The following users thanked this post: core

Offline rf-loop

  • Super Contributor
  • ***
  • Posts: 4135
  • Country: cn
  • Born in Finland with DLL21 in hand
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #55 on: November 14, 2018, 07:10:16 am »
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.
EV of course. Cars with smoke exhaust pipes - go to museum.
Wises must compel the mad barbarians to stop their crimes against humanity. Where have the (strong)wises gone?
 

Online nctnico

  • Super Contributor
  • ***
  • Posts: 28429
  • Country: nl
    • NCT Developments
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #56 on: November 14, 2018, 07:15:04 am »
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.
 

Offline ahopeTopic starter

  • Contributor
  • Posts: 34
  • Country: no
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #57 on: November 28, 2018, 09:22:29 pm »
Hi all,

issue is now resolved.  Siglent provided new boards and everything now checks out fine and within specs again.  Verified against accurate voltage sources and the original test circuit where i discovered the problem in the first place.

One last thing: I ordered brand new 10A FAST fuses for the rear fuse panel! 
thanks to siglent for great service.

So to all you out there - I am still a big fan of Siglent. based on this experience i will continue to buy more instruments from them.  I am very happy with my 3045X and my 1202xe.


/andreas
« Last Edit: November 28, 2018, 09:33:32 pm by ahope »
PDP10 6502 6809 68000 PDP11 8088 x86 ND5000 STM32 ESP32
From bare metal to the cloud
 
The following users thanked this post: rf-loop, tautech

Online Kleinstein

  • Super Contributor
  • ***
  • Posts: 15151
  • Country: de
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #58 on: December 09, 2018, 01:18:47 pm »
If Siglent is smart they fit a 7A fuse and fix current sensing circuitry so it cannot be damaged before the fuse blows.
7 A fuses are not a common size, but there are 6.3 A and 8 A available.

So maybe downgrade the specs to 6 A and use a 6.3 A fuse in the back.
 

Offline al777

  • Contributor
  • Posts: 37
  • Country: ca
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #59 on: July 22, 2023, 07:02:49 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.

Sorry folks... I know it's a 5-year old topic... I'm making a zombie I guess... :-)... But just so that the new info gets indexed by Google and someone like myself will save time on this topic in the future, here is what I've found.

First of all, on the new SDM3065X (non-SC, factory calibration is March 2023) the rear panel fuse is a glass-body one, marked as "T10AL250VP", with LittelFuse ("LF") logo, it's resistance (if anyone cares) is 4.575 milliohms, as measured with the RC3563 milliohm meter. There are 5 agency approval logos on the other cap.  My best guess is: it's the LittelFuse Series 218 5x20mm glass body time-lag fuse.

Second, I wanted to buy spares, just in case as incidents do happen - and I thought Fast Blow series would potentially be better (that would be LittelFuse Series 217). What I've found by reading datasheets is some new knowledge I wanted to share here.

The Time-Lag Series 218 outpaces the Fast Blow Series 217 for overload currents of 210% and only gets behind above that overload level.

218 series (slow) @ 210%: 120 seconds maximum; while 217 series (fast) @ 210%: 30 minutes maximum.

So, for DMM overload protection use, especially if there is an internal Time-Lag fuse for 12A - use of the external Time-Lag series fuse is well justified. Otherwise the "fast blowing" external fuse may allow the internal fuse to open first, at currents between 10A and 20A. Certainly, if you try to measure voltage of a low internal resistance source with DCA input :-) - then yeah, fast blow will be faster, but at 100's of amperes the damage may still happen... to both fuses and the DMM itself... Besides, slow characteristics may help in real life work, when your load (DUT) is capacitive for example... may save you few bucks on fuse replacements due to inrush current spikes...

So, in my opinion - the right replacement external fuse for SDM3065X is LittelFuse Series 218, glass body Time-Lag T10AL250V, here is the datasheet link:
https://www.littelfuse.com/~/media/electronics/datasheets/fuses/littelfuse_fuse_218_datasheet.pdf.pdf  (double .pdf at the end is not a typo).
They now go to my next Digikey order's list, $2.63CAD qty 1.

BTW, I've checked LittelFuse's ceramic body Time-Lag fuses as well - interestingly, while they do have way higher interruption capacity (not often a necessity for a bench meter) - they do what the label says, they lag behind, in a "mild overload" zone as well. So, Siglent engineers did choose the right fuse - that's my view of course :-). I'm not associated with Siglent in any way :-)!

Hope this will help someone to save time looking for the right replacement fuse for SDM30x5X DMMs. I'll now leave this old topic alone :-). All the best, folks!
 
The following users thanked this post: Performa01

Offline KungFuJosh

  • Super Contributor
  • ***
  • Posts: 3163
  • Country: us
  • TEAS is real.
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #60 on: July 22, 2023, 07:14:28 pm »
I think the model number for the 10A fuse you're referring to from LittleFuse is 0218010.HXP.
"Right now I’m having amnesia and déjà vu at the same time. I think I’ve forgotten this before." - Steven Wright
 
The following users thanked this post: al777

Offline al777

  • Contributor
  • Posts: 37
  • Country: ca
Re: Siglent SDM3045X mA current measurement - weird behaviour
« Reply #61 on: July 22, 2023, 07:28:42 pm »
I think the model number for the 10A fuse you're referring to from LittleFuse is 0218010.HXP.
Thanks, KungFuJosh!

...or 0218010.TXP or 0218010.MXP... I think those are packaging variations, same fuse. Few cents difference between them, I usually add to the basket those which have the highest stock at the moment, to make sure my near-future order will not be delayed :-).
 
The following users thanked this post: KungFuJosh


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf