Curious scanner amp

[ZeroPoint]

The first projector I ever bought was a cheap 310mW RGV chinese box for a couple hundred bucks back in 2010. That was the projector that started this hobby for me. Recently I had decided to gut the thing and modify it to suit a particular project I'm working on. I was hoping to reuse the scanners that were in it since everything still works and I don't need anything special for this purpose. I did, however, buy a new ILDA board from Goldenstar that comes with an SD card slot. The SD card feature is essentially what I'm after however I am also replacing the lasers and driver with a higher powered 405nm laser. When it came time to wire up the new ILDA board to the existing scanner amps I noticed that the new ILDA board has a three wire output for the X scanner amp and a separate three wire output for the Y scanner amp, as I expected it would, however, the old amp only has a single three pin connector for the X and Y scanner inputs. I examined the amp, the old ILDA board and the old DMX board and it literally only uses 3 wires to control both axis scanners. Unfortunately this seems to mean that I can't use the new ILDA board with these scanners but now it has me wondering how the old design even worked. I assumed all scanners used separate +, - and ground wires for the signals to each amp. How then do they get the same function with both scanners sharing the same three wires? Perhaps what I thought was +, - and ground is actually +, ground and a feedback wire. In this case maybe the cheap design just has the two positive wires for the scanners and they share a ground while eliminating the feedback wire? I'm certainly a bit confused and disappointed. maybe I can find a way to wire in the new board if I knew how the old one worked. I'm curious to know other's thoughts. Thanks for the help.

[ZeroPoint]

Update with new question. I've managed to figure out the wiring issue. Turns out my suspicion was correct. The amp uses a common ground for both scanners and eliminates the third wire from both X and Y which I still assume is some type of feedback wire. My new problem (which I guess technically is an old problem since it was also present with the old ILDA board) is that one of the scanner channels doesn't seem to be operating properly. There is no visible scanning when the laser shines on it, however, if I touch it gently and put my ear to it I can feel and hear that it is actually vibrating, it's just too soft to move the beam.It is definitely the amp channel and not the scanner because I have tried both scanners on both channels. both scanners work. My first assumption was that the TDA2030A amplifier chip was bad but when I took voltage measurements at the chip of both channels all of the inputs and outputs were comparable. I then took voltage measurements at the scanner itself and again all the numbers were comparable on both channels. If the scanner is getting similar voltages from both channels how can it be that it fails to operate on one channel? This thing is baffling me. Again, any insight or suggestions would be appreciated.

[ZeroPoint]

Ok, admin can delete this entire thread lol. Apparently I was using a poor ground point for my voltage measurements. I repeated them at the chip using the actual ground screw on the power supply and it became immediately apparent that the culprit channel has a near zero voltage output. Looks like I just need to replace the amplifier chip. I guess posting about all of this helped me organize my own thoughts enough to solve my own issue.

[VJ AIWAZ]

does the amp look anything like this ?
if so i have a few laying around

[ZeroPoint]

Yes, it is exactly that amp. I ordered a couple TDA2030A amplifier chips from Jameco, everyone else has stopped selling them. Ill post again when the chips arrive and I have a chance to change out the faulty one. If it doesn't fix my problem Ill be interested in buying an amp off of you if you don't mind. Otherwise, I should be good to go. Do you have a link to a manufacturer? I tried looking for some info on the set but couldn't find anything. I realize that these are bottom of the barrel scanners but I'm curious about them.