Hi Everyone
I am having problems with one of the four SMD 1.2 kits that I put together. I originally ordered three and one of them was weak in power so I set it aside and simply ordered another to put together.
I originally thought maybe I had a bad L298 H bridge and finally got a electronics order together to get another one. I have replaced this chip with no effect.
The problem is that there is basically no torque or power when a stepper motor is attached to this board and stepping.
I can stall rotation of the stepper motor shaft by gripping with my thumb and index finger; a good driver board will flip the stepper motor over.
Things I have done to try fix or isolate this are:
1. Set TP1 to .5 volts like I have done on my other boards.
2. Swapped the L297 chips between boards.
3. Verified continuity between the L297 step phase pins and the inputs to the L298 chip.
4. Verified continuity between the output pins on the L298 and the stepper motor connector.
5. Verified VSS to the L298
6. Re-soldered every connection on the board.
Observations:
When this board powers up the phase LEDS are always out.
When stepping the phase LEDS change color normally in comparison to the other boards.
When it is stepping and it pauses the phase LEDS are always out.
When power is on the stepper motor is not stepping it is holding position firmly.
Only variable in my testing is this board verses a good board.
Any suggestions?
