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FNIRSI-1014D 100MHz Digital Storage Scope (Read 133 times)
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FNIRSI-1014D 100MHz Digital Storage Scope
Sep 4th, 2021, 8:51am
 
I recently purchased A FNIRSI-1014D LCD Digital Oscilloscope from MRAM Electronics - a local Surplus Electronics and Parts dealer.
 
He was selling them for $199, which is a very fair mark up from the typical cost on AliExpress, considering that I got "Instantaneous Shipping" (Cash and Carry).
 

Photo from AliEpress Venor Listing
 
 
However, after I got it home, I soon discovered it had a problem.
 
For a signal source, I connected it to my Koolertron 15MHz High Precision DDS Signal Generator Counter, which was also essentially new to me.  I purchased the Signal Generator from a vendor at the "World's Longest Yard Sale" back in August, and I had never tried it out.  I think I paid $10.00 for the Koolertron Signal Generator, and I have to say I'm very impressed with at least that half of the setup.  It's possibly my best purchase of the 3 states we visited during the "World's Longest Yard Sale".
 
So the problem with the FNIRSI-1014D Oscilloscope was that Channel 1 seemed to be stuck in AC coupling.  I could change the setting in the pop-up Ch 1 Menu, but no matter how it was set, the scope acted as if the input was AC coupled.  I checked test leads and the probes with my Fluke Scopemeter, thus verifying that FNIRSI-1014D was faulty.  I then realized that selecting AC/DC coupling for Channel 2 was not working correctly either.
 
Figuring it was a firmware issue, I started searching the web, but as of this writing, I do not see a firmware for the FNIRSI-1014D on the FNIRSI Support page.
 
A little more research got me to other people reporting the same problem, and eventually to this YouTube Video by Nercy Eletrônica (AKA NB Electronica -- Portuguese Language).  Without knowing Portuguese, and in fact without any sound at all, I could clearly see that he was describing the same problem, although his Channel 2 seemed to work correctly.
 
He also showed the fix -- Apparently, FNIRSI is having problems getting 2 of the components soldered in the right way.  The following screen shot from Nercy Eletrônica shows the board after he soldered the chips in correctly.  The chips in question and the proper orientation is shown by the arrows:
 

Photo is a screen shot from Nercy Electronica Video
 
Things to note:
1.  As mentioned, the screen shot shows the correct installation of the components in question. Note the extra solder on the component on the left showing that this picture was taken after his repair. (I'm not criticizing his work -- Mine now looks worse.)
3.  I believe that the markings on the PC board (under the components) are correct, and can be referenced to verify correct component installation.
4.  Note other component placement issues in the same picture.  (Are those piggy-backed components?)
5.  As mentioned, both of the marked components were installed upside-down on my unit, thus affecting both channels.
 
 
Steps to Repair:
1.  Disassemble the unit.  This consists of removing 3 small screws from the recessed holes at the top, and a total of 4 screws from near the folding feet.
2.  Disconnect the power wires from the PC board.
3.  Carefully heat and open the EMI shield from 1 or both input circuitry areas.
4.  Examine the installation orientation of the 2 four pin devices shown in the screen shot.
5.  Desolder one or both components if installed upside-down.
  a.  At first, I figured I could use my de-soldering equipment to remove the components.  I ended up doing it exactly as show in the video:
  b.  Add solder to form a bridge between the 2 pins on each side of the component.
  c.  Heat the now-bridged side to free both pins, and carefully lift that side of the component.
  d.  Repeat on the other side, thus freeing the component.
  e.  Remove excess solder from the pads and component with fine solder wick.
  f.  Clean the area with an alcohol wipe in preparation for re-installation.
  g. Orient the component correctly, and tack solder in place.
  h. Solder the component with a very small amount of additional solder if necessary.  Be sure to avoid solder bridges this time.
6.  Again use solder wick to clean up the shields and the hole in the PC board for the tab.
7.  Solder the EMI shield back, making sure it is fully down on the PC board.
8.  Reassemble the unit.  Don't forget to connect the power wires correctly.
 
After re-assembly, both channels on my unit work correctly.  With the inputs set to DC, and a DC offset applied to the signal, the waveform moves up or down as it should.
 
Thanks to Nercy Electronica for his excellent skill in finding the problem, excellent repair skills, and a great video.
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« Last Edit: Sep 15th, 2021, 8:03am by Administrator »  

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Re: FNIRSI-1014D 100MHz Digital Storage Scope
Reply #1 - Sep 4th, 2021, 1:14pm
 
So what do I think of the FNIRSI-1014D 100MHz Digital Oscilloscope now that mine is working "properly"?
 
 

Photo Linuxslate.com.  Test setup with  FNIRSI-1014D and Kooltech Signal generator.
 
Well, If you want the short version of this review, note that I put the word "properly" in quotes.
 
I cannot recommend the purchase of the FNIRSI-1014D given the gross and apparently on-going quality control failures, firmware issues, and problems that I and others have reported.
 
I purchased mine locally, so I could have returned it to the store where I bought it from.  Others would have to deal with sending it back to China, and possibly issues with language and different attitudes in different cultures about returns and or refunds.  Even in my case, asking for a refund from a local small business run by people I consider friends would have been at least a bit awkward.  As mentioned I am thankful that I am able to make a repair like this, and for the help from Nercy Eletrônica.  I realize that repairing brand-new merchandise is not something everyone can or would want to take on, and nobody should have to.
 
The concept of trust when it comes to test equipment should also not be overlooked.  Trust is the reason Fluke, Tektronics, Hewlett-Packard, and other companies charge premium prices for their products.  Engineers, technicians and lab managers continue to gladly pay those prices because they know they are getting a product that not only works, but also produces results they can bank their careers on.
 
I would strongly suggest that even budget or casual hobbyist users spend the extra $40 to $70 for a similar unit such as the Hantek DSO2D10.
 
If you want to accept the risk of hardware failure and/or inaccuracy, purchasing (and possibly repairing) a vintage or surplus CRT oscilloscope is another, and IMHO opinion better, option for those wanting an oscilloscope without spending thousands of dollars on brand-new lab equipment*.
 
That said, I am now happy with mine, and I intend to keep it.  I may even go as far as to say that having to fix it boosted my sense of ownership.  It contains (a little) of my own work.  It is unique.
 
i also have to give it credit for a bright and crisp screen.  At least until you encounter one of the firmware bugs, the user interface looks very nice, and is intuitive to navigate.
 
The FNIRSI-1014D is also small and easily portable.  Since it includes a fold-down handle, and is powered by USB, all that is needed is a portable phone charger (battery pack) -- and perhaps a bit of double sided tape -- to make it a truly portable oscilloscope that retains a full-size screen.  Current draw is about an amp, so it would run for several hours from a 5000mah phone charger.
 
Given that the repair was quick (I literally had the back off for less than 15 minutes) and did not incur any significant additional cost, I still feel that I got a good deal.  I like it's features, appearance and portability.  
 
I will not however, blindly trust it, or ever rely on it for a critical measurement.  I will always look at that 7" LCD screen with suspicion.
 
*NOTE:  CRT Oscilloscopes employ lethal voltages, as well as other hazards including CRT implosion risk.  Repairs/adjustment should be attempted only buy those with the requisite skills.
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« Last Edit: Sep 12th, 2021, 9:58pm by Administrator »  

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Re: FNIRSI-1014D 100MHz Digital Storage Scope
Reply #2 - Sep 5th, 2021, 1:59pm
 
A little more information about repair of  FNIRSI-1014D 100MHz Digital Oscilloscopes exhibiting issues with AC/DC input coupling:
 
If the components mentioned in the above posts are missing all together, or are damaged in the repair process, here is the information about these components:
 
They are KAQY214 Series Optically Isolated Solid State Relays.  The specific part/package used in the FNIRSI-1014D is KAQY214S.  The Data Sheet is Here.
 

 
 
If you need a replacement, there are numerous vendors on AliExpress and eBay selling them.  A pack of 10 costs about $5 to $10 on eBay, shipped from China (Shipping may add a few dollars to that price.)
 
 
 
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