Anyone cracked open a Hanna checker before?

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
310
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
I've got a Hanna nitrite checker that I very rarely use anymore, so I'm thinking about sacrificing it for learning purposes.

I tried getting it open, but it's looking like I'll have to permanently destroy the shell to get into it.

I thought it was odd that there's an 8 pin connector on the base when at first glance it looks like the base cap is simply bringing positive from the battery into the unit. I probed each of the slots in the base cap to the positive battery tab and only get continuity between that tab and a single slot.

What are the other 7 pins for? I'm wondering if they perhaps expose serial communications for programming the firmware, factory calibration, etc. Maybe 1-2 of the pins expose the button to automation for calibration. Considering how hard, if not impossible it is to remove it from the shell.

So, before I destroy this thing, has anyone already dug into this?
 

garbled

Well-Known Member
View Badges
Joined
Nov 10, 2018
Messages
772
Reaction score
1,044
Rating - 0%
0   0   0
My guess would be a JTAG header, or similar debug/programming port. Take a look at hackaday, they have a few good articles on reverse engineering circuits and teardowns if you haven't done one before. Would love to see pics!
 

StlSalt

Active Member
View Badges
Joined
Sep 30, 2020
Messages
480
Reaction score
626
Location
St. Louis, MO
Rating - 0%
0   0   0
Pics would be nice, the screen is going bad in my Phos ULR checker. I was wondering if I could just replace the LCD screen.
 
OP
OP
Joekovar

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
310
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
A dremel without a flexible shaft is just uncivilized. IMG_20210306_180012755_HDR.jpg

The lid can be removed easily.
IMG_20210306_180052684_HDR.jpg

Careful not to go too deep with the cutoff wheel.
IMG_20210306_180337241.jpg

Had to work around the bottom to crack it open.
IMG_20210306_180735487_HDR.jpg

First look inside.
IMG_20210306_180830250_HDR.jpg

Some of the tabs from the white top piece are glued pretty well to the green shell. These definitely aren't meant to be opened.
IMG_20210306_180844433_HDR.jpg

IMG_20210306_180854779_HDR.jpg

No turning back now.
IMG_20210306_181144589_HDR.jpg

Insides.
IMG_20210306_181205760_HDR.jpg

IMG_20210306_181213667_HDR.jpg

IMG_20210306_181224092_HDR.jpg

Screen.
IMG_20210306_181239419_HDR.jpg

The chip.
IMG_20210306_181437834.jpg

IMG_20210306_181513582.jpg

IMG_20210306_181526415.jpg

IMG_20210306_181557968.jpg

The red numbers are the header pins in this orientation.

5 goes to -1.5vdc
4 goes to +1.5vdc
8 goes to the left most pin pointed to by the red line.
IMG_20210306_181213667_HDR~2.jpg

IMG_20210306_181437834~2.jpg

That's as far as I've gotten so far. There's a lot of information in the datasheet of the pic16F913.
 

Attachments

  • IMG_20210306_181612764.jpg
    IMG_20210306_181612764.jpg
    206.2 KB · Views: 85
  • IMG_20210306_181626195.jpg
    IMG_20210306_181626195.jpg
    291.2 KB · Views: 95
  • IMG_20210306_181759394_HDR.jpg
    IMG_20210306_181759394_HDR.jpg
    60.8 KB · Views: 79
  • IMG_20210306_181811595_HDR.jpg
    IMG_20210306_181811595_HDR.jpg
    72.7 KB · Views: 79
  • IMG_20210306_181858084.jpg
    IMG_20210306_181858084.jpg
    74.3 KB · Views: 83
  • IMG_20210306_181902995.jpg
    IMG_20210306_181902995.jpg
    83 KB · Views: 79
  • IMG_20210306_181909903.jpg
    IMG_20210306_181909903.jpg
    87 KB · Views: 80
  • IMG_20210306_181922139_HDR.jpg
    IMG_20210306_181922139_HDR.jpg
    76 KB · Views: 91
  • IMG_20210306_182021562_HDR.jpg
    IMG_20210306_182021562_HDR.jpg
    116 KB · Views: 88
OP
OP
Joekovar

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
310
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
Header #3 goes to "RB7/ICSPDAT/ICDDAT/SEG13" on the PIC.

I think header #2 goes to "RB6/ICSPCLK/ICDCK/SEG14".

The back side of that chip's not easy to probe...
 
Last edited:

Dennis Cartier

Valuable Member
View Badges
Joined
Aug 25, 2016
Messages
1,947
Reaction score
2,384
Location
Brampton, Ontario
Rating - 0%
0   0   0
That is very neat. Thanks for posting the pics.

All the type of components included are what I expected. It is neat that they are using of the shelf PIC's and not some custom ASIC. The sensor looks like it only uses 2 pins, so I am guessing straight photo resister. Both the LED carrier board, and sensor board look like there would be a combination of them for the other models of the Hanna checker. Each of the checkers use a slightly different wavelength of LED.
 

Joe31415

Valuable Member
View Badges
Joined
Dec 25, 2020
Messages
1,087
Reaction score
797
Location
Milwaukee
Rating - 0%
0   0   0
If you want someone that's really good at reverse engineering, look into sending it to BigCliveDotCom, this is what he does. Granted, he's in Wales or Isle of Man, so shipping might be expensive.
 

garbled

Well-Known Member
View Badges
Joined
Nov 10, 2018
Messages
772
Reaction score
1,044
Rating - 0%
0   0   0
I would have thought it needed a color sensor, not just a simple LED. It's not a titration....
 
OP
OP
Joekovar

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
310
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
There's 3 traces on the LED board. The center has continuity directly to -1.5vdc, the right branches off somewhere before going through a 499 ohm resistor to -1.5vdc, the the left appears to go to a transistor.

The button pulls something to -1.5vdc, but I'm not sure what. There's no continuity between the other side of the button and any of the pins on the PIC so it's doing more than pulling an input low.

I'm really interested in the ICD capabilities of the chip. Ultimately I want to be able to capture the final reading with an Arduino.
 
OP
OP
Joekovar

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
310
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
Header #1 goes to VDD on the 27L2C opamp.

#6-7 head under cuvette holder somewhere. Possibly behind the LCD. I'm going to have to find my soldering iron to melt the posts that were melted to hold the cuvette holder in place.

I came across a thread mentioning an undocumented display if you hold the button when you turn it on. All of my checkers show me the model number, then a number like 1.08 or 1.07 when I try it.

I suspect this second number is a per-unit calibration factor. The firmware would generate the same reading for all alike checkers, and the result would be multiplied by this calibration factor to account for variations in component batches. I think this press and hold function exists so when someone sends their unit to Hanna because the calibration test kit says it's out of range, technicians can easily determine what checker it is in case the label has worn off, and quickly decide whether to update the firmware with a new calibration factor, or just replace the unit if the calibration factor is already far from 1.0
 

taricha

5000 Club Member
View Badges
Joined
May 22, 2016
Messages
6,484
Reaction score
9,996
Rating - 0%
0   0   0
This is great.
I took one apart a while back and found some of the same things, but I also looked at some different things, like the LED and the optical filter on the photo detector.
The light sensor side outputs a voltage in response to light intensity even if there is no power connected, no battery in place at all.
The sensor is not very wavelength specific, the LED is very narrow, and that's what makes the checker specific.

I'll post details later when I get a chance.
 

taricha

5000 Club Member
View Badges
Joined
May 22, 2016
Messages
6,484
Reaction score
9,996
Rating - 0%
0   0   0
Here's some notes from when I took apart my Low Range Iron checker.

On mine the only part that actually had to be removed is opposite from the hinge side, where the white top piece is glued to the plastic body cover. Once the plastic tab is separated, the plastic body ought to come off the electronics.

Screen Shot 2021-03-08 at 6.20.39 AM.png


(I figured out after cutting, that most of the cutting wasn't necessary)


Screen Shot 2021-03-08 at 6.24.03 AM.png

This is a closeup of the Photocell and the attached filter.


This is a closeup of the LED.
Screen Shot 2021-03-08 at 6.25.47 AM.png


The LED is a 571-2nm yellow-green with a very narrow width. FWHM is only about ~11nm wide. The wavelength is within manufacturing tolerances of 575nm which is what it’s labeled as. I checked to see if the cyan filter was being used to shift the LED peak, but it does not shift the peak by even a nm. The filter allows all LED light through. It simply blocks anything longer wavelength than the LED itself, so any fluorescence would be blocked.
Later I realized many light sensor devices have this similar cyan filter, so it's not specific to the LED, but simply to cut off the photocell from picking up extraneous IR, or other unrelated long wavelength light. If I found the correct specs for a similar photocell, these things have a sensitivity that's throughout entire visible, and very high in IR. So I think the filter is just to tame that behavior.

Screen Shot 2021-03-08 at 6.29.58 AM.png

(Optical Properties of the LED and filter over the photocell).

I tried and mostly succeeded to run the checker through a calibration process while measuring the current and voltage. What I found was that the calibration routine is surprisingly complex.

Screen Shot 2021-03-08 at 6.33.46 AM.png

attempting to run the disassembled checker through a measurement cycle, and though it would not finish because the room light caused a “Low Light” or "Hi Light” error, it would do the “C1”-blank checking phase. Below are the Voltage and Current performance of the
LED during the “C1” check phase. It starts, then in the long calibration It will vary the light brightness every couple of seconds for about 30 seconds. Max voltage measured was ~1.9V, minimum lit voltage ~1.8. Max current was 18mA with min lit current 10mA.
(when voltage went off the chart, is where my hands slipped)

So for calibration, It shoots a series of measurements, getting the photocell response at a bunch of different LED brightness through the blank "C1" cuvette.
 

Sguiv6

New Member
View Badges
Joined
Jun 27, 2021
Messages
5
Reaction score
3
Location
Bundaberg
Rating - 0%
0   0   0
Here's some notes from when I took apart my Low Range Iron checker.

On mine the only part that actually had to be removed is opposite from the hinge side, where the white top piece is glued to the plastic body cover. Once the plastic tab is separated, the plastic body ought to come off the electronics.

Screen Shot 2021-03-08 at 6.20.39 AM.png


(I figured out after cutting, that most of the cutting wasn't necessary)


Screen Shot 2021-03-08 at 6.24.03 AM.png

This is a closeup of the Photocell and the attached filter.


This is a closeup of the LED.
Screen Shot 2021-03-08 at 6.25.47 AM.png


The LED is a 571-2nm yellow-green with a very narrow width. FWHM is only about ~11nm wide. The wavelength is within manufacturing tolerances of 575nm which is what it’s labeled as. I checked to see if the cyan filter was being used to shift the LED peak, but it does not shift the peak by even a nm. The filter allows all LED light through. It simply blocks anything longer wavelength than the LED itself, so any fluorescence would be blocked.
Later I realized many light sensor devices have this similar cyan filter, so it's not specific to the LED, but simply to cut off the photocell from picking up extraneous IR, or other unrelated long wavelength light. If I found the correct specs for a similar photocell, these things have a sensitivity that's throughout entire visible, and very high in IR. So I think the filter is just to tame that behavior.

Screen Shot 2021-03-08 at 6.29.58 AM.png

(Optical Properties of the LED and filter over the photocell).

I tried and mostly succeeded to run the checker through a calibration process while measuring the current and voltage. What I found was that the calibration routine is surprisingly complex.

Screen Shot 2021-03-08 at 6.33.46 AM.png

attempting to run the disassembled checker through a measurement cycle, and though it would not finish because the room light caused a “Low Light” or "Hi Light” error, it would do the “C1”-blank checking phase. Below are the Voltage and Current performance of the
LED during the “C1” check phase. It starts, then in the long calibration It will vary the light brightness every couple of seconds for about 30 seconds. Max voltage measured was ~1.9V, minimum lit voltage ~1.8. Max current was 18mA with min lit current 10mA.
(when voltage went off the chart, is where my hands slipped)

So for calibration, It shoots a series of measurements, getting the photocell response at a bunch of different LED brightness through the blank "C1" cuvette.
My LED is gone on my Nirtite ULR, would this work for a replacement LED?



Thanks Guys! Very interesting topic :D
 

Sguiv6

New Member
View Badges
Joined
Jun 27, 2021
Messages
5
Reaction score
3
Location
Bundaberg
Rating - 0%
0   0   0
I found that with a little upwards pressure it pops right out. At first it seems like you shouldn’t be pulling it but it comes out in one piece
 

Attachments

  • D3BDF9DF-7737-4AF4-8C48-727C15EA73C7.jpeg
    D3BDF9DF-7737-4AF4-8C48-727C15EA73C7.jpeg
    89.9 KB · Views: 77
  • 88A7A780-B8E5-4DF9-A972-817EB7972B3C.jpeg
    88A7A780-B8E5-4DF9-A972-817EB7972B3C.jpeg
    106.3 KB · Views: 76
  • 9530FA2A-D60B-4717-A6F2-129907D9F0A1.jpeg
    9530FA2A-D60B-4717-A6F2-129907D9F0A1.jpeg
    100.3 KB · Views: 72

taricha

5000 Club Member
View Badges
Joined
May 22, 2016
Messages
6,484
Reaction score
9,996
Rating - 0%
0   0   0
My LED is gone on my Nirtite ULR, would this work for a replacement LED?

That LED looks similar, but the wavelength needs to be 525nm for the ULR Nitrite checker. I'm sure there are many other parameters that need matching for this to work, but it ought to be possible.
 

schafon

Active Member
View Badges
Joined
Jul 28, 2021
Messages
151
Reaction score
36
Location
Florida
Rating - 0%
0   0   0
Bumping!!
Is there someone who manage to get a reading using the debugging port?
I'm working on a cool project that I need to get the reading to Arduino / Raspberry pi
 
Back
Top