2

enter image description hereI’ve researched and cannot solve on my own. I need to reconnect the 4 AA power source back to this board. There are no markings like B+ or B- to make it easy. I see VDD and VSS. Which seem to represent different things depending on what you read. I have cleaned the solder points and it’s ready to go. Trial and error is not helping. Thanks for the initial feedback. I updated this post with the other side. Apologies. Just figuring out the forum.

For those who have offered help to me as I am a beginner, thank you so much!!

enter image description here

JPK
  • 21
  • 2
  • Do you know what the PCB function is? Is the IC an [EMD812 motor driver](http://www.elite-ent.com.hk/upload/090603120608EMD811_&_812.2009.pdf)? – JYelton Aug 09 '23 at 00:37
  • Hello. It’s for a child’s toy. Fire truck. The motor connections are for the wheels. I’be identified that. – JPK Aug 09 '23 at 02:04
  • 1
    WTH is "B+" and "B-"? That's some home-made garage standard you just came up with. The board _is_ using engineering de facto standard terms VDD and VSS. Using established engineering terms _is_ the easy way. If you don't know them, then that's not a fault of this PCB manufacturer. – Lundin Aug 09 '23 at 09:01
  • 1
    [What is the difference between VCC , VDD , VEE , VSS](https://electronics.stackexchange.com/questions/17382/what-is-the-difference-between-v-cc-v-dd-v-ee-v-ss) – Lundin Aug 09 '23 at 09:03
  • I didn’t come up with anything. I have seen boards with that printer on it. I’m a hobbyist. It says this forum is for students and people learning. I’m not blaming the board. I’m trying to learn. If you don’t want to help, maybe just keep quiet. – JPK Aug 09 '23 at 19:02
  • @JPK Just a note, this is not a forum, it is a Q&A. The difference is that there is no "conversation" about an issue, just questions and answers (and occasional comments for clarifying details). – JYelton Aug 09 '23 at 21:55
  • JYelton. Your answer was spot on and VERY helpful. For what it is worth for the troll above. I have two boards sitting in front of me. One has + BAT - printed. Pretty easy. The other has V+ V- printed. Also easy. I don’t appreciate a non answer from a troll calling my question home-made garage. I didn’t come here to be insulted. – JPK Aug 10 '23 at 00:09

1 Answers1

4

VDD is another "name" for positive, and VSS is another name for negative.

This is where reverse engineering comes into play. Find the datasheet for the IC, and determine what its VCC (positive) and GND (negative) pins are. If it's an EMD812, then here is the pinout:

EMD812 8-DIP Pinout

Follow pin 2 and 7 on the PCB traces and you should be able to determine where the battery positive connects.

Follow pin 4 and 5 in the same manner to determine where battery negative connects.

JYelton
  • 32,302
  • 33
  • 134
  • 249