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I am tying to determine where the PCB traces are going in order to figure out if this is using the TM1650 or something else. Most of these (this is from a pool pump) uses the TM1650 but there are some that use some other chip.

From what I can gather, since the chip is covered in silicon, is that two of the pins (SCL/SDA) are on the correct pins of the chip. Those being pins 2/3 respectively. The others coming from the LED segment do not seem to match the TM1650 pin positions.

I have tried to trace them the best I could:

enter image description here

The original image without my color traces:

enter image description here

The front of the PCB:

enter image description here

Here is the schematic of someone who has already done something like this - allthough they had a different version than I do:

enter image description here

I'm not sure where the C, DP, A, and B traces are going to. With my current traces it looks like this:

enter image description here

It would be great if someone who knows more about traces and such on PCBs to lend me a hand with determining if it's the TM1650 pinout or not and if my traces are even correct as-is.

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  • \$\begingroup\$ Do you have any information / pictures about what is at the other end of J1? \$\endgroup\$
    – jonathanjo
    Commented Mar 29, 2023 at 17:59
  • \$\begingroup\$ The chip is covered in silicone, not silicon. All the silicon is inside the package--or at least it better be! \$\endgroup\$
    – Hearth
    Commented Mar 30, 2023 at 3:36

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It certainly looks like it to me. Tracing can be tricky from photos because of hidden tracks, focus, reflections and so on, but as far as I can tell ...

SCL, SDA and power and ground all look right. Tracing the digit selects too seem correct. (You made a couple of errors in your tracing, specifically red which appears to drop down across the wire link to pin 1 of chip.) The seven-segment display appears to be wired with the segments remapped, which just changes the software.

Your circuit diagram appeas to be of an different board, perhaps intended to connect to this one: note that while the DISPLAY BOARD signals appear to match your board, the pinout does not. And if the LED and switches aren't connected as expected by the transmitting end, it's likely to display incorrectly and/or misunderstand the key presses.

This is what I believe the circuit to be, but some of it is just guessing (especially which switch is on which segment line.) On J1, I've labelled GND as Pin 1, but who knows which is Pin 1 on your equipment. R3, R4, R5, R6, R7 all are marked 0 ohms, hence omitted. enter image description here

This is the tracing as far as I can make out. enter image description here enter image description here

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  • \$\begingroup\$ Alright thats good to know. And from your traces it looks like (going left to right) that its SCL, SDA, 5v, GND correct? \$\endgroup\$
    – StealthRT
    Commented Mar 29, 2023 at 20:25
  • \$\begingroup\$ That's what it looks like to me. \$\endgroup\$
    – jonathanjo
    Commented Mar 30, 2023 at 13:11
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    \$\begingroup\$ Great writeup Jonathan! Thanks! \$\endgroup\$
    – StealthRT
    Commented Apr 1, 2023 at 2:52
  • \$\begingroup\$ Can I ask what you're doing that you need to understand this board? \$\endgroup\$
    – jonathanjo
    Commented Apr 1, 2023 at 2:55
  • \$\begingroup\$ troublefreepool.com/threads/automation-of-intex-swg.228606 \$\endgroup\$
    – StealthRT
    Commented Apr 1, 2023 at 19:19

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