Hello EEVBlog! I am a novice to circuit reverse engineering; and frankly, for this project, I'm hoping for a shortcut.
I recently picked up this 20 cue remote control firing system:
https://www.aliexpress.com/item/1005001737207464.html?spm=a2g0s.9042311.0.0.3b534c4dZm7Mhx The kit was originally advertised as "expandable to 100 cues". After much back and forth with the seller, they finally stopped responding to me and changed the listing (it now no longer says "expandable" - hah!). However, I noticed that the controller unit can train the receiver unit cues to whatever it transmits, and all the units appear to support digits up to 99. I decided to open the controller and see if there was an easy way to change the controller to train cue numbers greater than 20 (even though the keypad would still show 1 - 20).
Immediately, I noticed that there were solder points labeled 40, 60, 80, 100, suggesting that a simple modification would get what I want. Unfortunately, I tried a straight shunt, and then a 330 Ohm resistor, but neither changed the behavior of the controller unit.
I started with the photos (attached), and I'm prepared to do the tracing and component measurements like what is recommended here:
https://www.eevblog.com/forum/beginners/pcb-to-scheme/msg2325273/#msg2325273However, I am concerned about 2 completely unmarked ICs that appear to be central to the controller's operation. I'm afraid that no matter how much tracing I do, I'll never figure out how to modify the device correctly because of these unknown ICs.
My questions:
1. Is anyone experienced with a device like this and can recommend the correct modification?
2. Should I go through the whole tracing/measuring process even though I don't know what the ICs do?
3. Any advice on identifying the 2 ICs?
Thank you in advance for any help you can offer!
-Cory