Fried Stepper Driver?

Hi,
I've been causing myself more problems here lately, but it started with my heatbed failing. So I tried to test the mosfet and accidentally touched the probe to a fuse instead of a bed terminal. I didn't blow the fuse but saw a spark and my lcd display lost all of its digits and only backlight was on. After ordering a new arduino thinking that was the cause, I found that it wasn't. But when I plugged the ramps and arduino into usb power only, I found that two of the stepper drivers got very hot quickly. After removing the two and then plugging in the usb power again, I could actually read the display but the text was still very dim. So I tried unplugging all four of the stepper drivers and I could read the display perfectly as before. So I'm thinking my problem is either with the Ramps board or the stepper drivers. And the reason I'd lean toward stepper drivers is because when the two drivers got really hot and the lcd was out, I tried swapping them out with a non-hot one and I could faintly read the lcd and the driver did not get hot in the same position that the other one had. What do you guys think? Have you ever heard of the stepper drivers hurting from a short or anything like this?
Thank you

If you somehow shorted a 12V line to the 5V line, you may have fried the logic side of the stepper drivers.

First thing to check: With no stepper drivers, what is the +5V line measuring (in Volts)? It should be pretty close to 5V. If so, then it's more likely the Arduino and LCD are OK, and just the stepper drivers are at fault.

Quote
Cefiar
If you somehow shorted a 12V line to the 5V line, you may have fried the logic side of the stepper drivers.

First thing to check: With no stepper drivers, what is the +5V line measuring (in Volts)? It should be pretty close to 5V. If so, then it's more likely the Arduino and LCD are OK, and just the stepper drivers are at fault.

Thanks. So I wasn't exactly sure which 5v line or if it mattered but I checked the line on I2C pins in the upper right of the ramps diagram and they were at 4.96v. Does that likely mean just stepper drivers or could the ramps board have problems? Is there any way of knowing which stepper drivers are bad or should I get all four new ones? Thanks

You could try them 1 at a time and see how it goes. I would also check the resistance of each stepper driver when removed from the circuit (red probe to VCC, black to Gnd).

If you have a 5V supply and a current meter (eg: multimeter in current mode, etc), you could JUST hook up the VCC and Gnd each stepper driver board and test. Connect VCC to the black probe on your meter, and the Red probe to your +5 supply. Gnd on the supply to Gnd on the stepper driver (Use the Gnd next to the VCC).

MAKE SURE the meter is set up to read current and that the Red probe goes into the current reading pin on your multi-meter, and make sure when you've finished you put it back in the resistance/volts pin (This depends on your type of meter - if it has separate holes, you'll short out stuff trying to measure a voltage if you're connected to the current pin).

You could then measure how much current each stepper driver is pulling, if they get hot without anything else applied, etc.