Help me debug ina333 load cell wiring (videos included)

[mdboss]

Hi everyone, I'm doing a sim pedal project with hall sensors and load cell.

Before putting all components on perf board, the load cell + ina333 was working fine. (connected with wires). Now after connecting them on a perfboard (with jst-xh connectors), analogRead on A0 is always around 520.

The hall sensors work fine.

The wiring diagram I followed is included. I also took pictures of both sides of the perfboard and marked my connections. I'm willing to provide more if needed. Here is a list of what I tried doing:

• recrimping jst-xh connector and testing I have same signal on ina333 pin an load cell side (good)
• bought NEW ina333 board because on the old one I shorted the trim pot.
• tried cleaning flux around ina333 pins (resulted in more stable readings, but still not reacting to load cell pressure)
• twisting the trim pot screw (no difference)
• changing from A0 to A3 (same readings)
• tested with multimeter all connections (no shorts)
• disconnecting VREF - GND connection on the ina333 board

---

Then I went to clean the flux more and record these videos of testing continuity of pins around the load cell (linked bellow).

At this point it was around 16h since I last plugged it in, and after plugging it in serial monitor was displaying 0 constantly and it was responsive to the load cell. This lasted around 30 seconds, then it had some noise where it jumped to ~300, back to 0 and then back to ~560 and now it stays around there.

Any ideas what could be causing this?

Videos:

ina333 and jstxh connector solder test

load cell connector wires test

[xfpd]

ProMicro pins look unsoldered (but for a couple). Post oblique image of ProMicro soldering.

[mdboss]

Yes correct, I soldered only the ones used, plus some extra ones to make it more sturdy.

[xfpd]

Common practice is to make all connections, so transient voltage or non-terminated wires have no effect.

[mdboss]

Okay, I will now do that. In the meanwhile I recorded my serial output after letting the board disconnected about 45mins.

values increasing

You can see that at the start value is 0 and values are responsive to the load cell pressure, after a while it starts spazzing out with values increasing eventually stopping around 350-600.

[LarryD]

@mdboss

I soldered only the ones used, plus some extra ones to make it more sturdy

• In the future, solder Dupont type female headers on the protoboard, plug the micro (with male headers) onto the PCB.
  Solder all header connections.
  If you have the option of using machine pin headers, do so.

• Also, clean your protoboard solder connections using a tooth bush and IPA.

[LarryD]

FYI

Share tips you have come across

Prototype Board Tools and Prototyping Board Construction. EDIT Rev 1.10 ( Thanks to PerryB ) The following post consolidates several past posts. Two PDFs are attached below. Tools For Making Prototype Boards discusses making tools used in the second PDF, Prototype Board Construction. Tools For Making Prototype Boards.pdf (3.7 MB) Prototype Board Construction.pdf (5.8 MB) [Prototyped Board Wire Soldering]

Share tips you have come across

Prototyping Wire Loop Connections using 30 AWG Wire Wrap Wire See also: 30 AWG wire wrap wire is a bit easier to use than the 38 SWG wire previously discussed. The process for making wire wrap wire Loops is slightly different than in the Shellac Post #1387. Kynar Insulation is easily removed using a proper stripping tool; unfortunately, this tool is around $25.00 to $30.00 The OK Industry makes these wire stripping and wrapping tools. What’s nice about Kynar insulation is it can sl…

Share tips you have come across

Prototyping Wire Loop Connections using 38 SWG Shellac Insulated Wire See also: Double Wire Connections on a Prototyping PCB The following is an excerpt from an upcoming PDF. Making a Hand Soldered Prototype PCB When soldering Shellac Insulated interconnecting wires, a shellac removing tool can be easily constructed. The tool is made from a small FR4 PCB board, a foil section holds a blob of solder. Heat this solder blob to 400°C, insert the end of a shellac insulated wire, the …

[mdboss]

Thanks for linking the docs, useful stuff.

Now I soldered all of the arduino pins @xfpd , and cleaned the whole board again, but the outcome is still the same - like in my last video of the arduino IDE, works for 20sec when left disconnected for a longer period of time. If I reconnect too soon, it starts with the random values spazzing from the start.

[LarryD]

@mdboss

Before putting all components on perf board, the load cell + ina333 was working fine.

• If the above is correct, you might have damaged components in the interim, you may have a soldering connection problem or you have not wired all connections.

• You can use an ohmmeter to confirm connections, check for opens, check for adjacent pin shorts.

• Use a voltmeter to confirm voltages going to pins, connectors and off board components.

• This does not look good: