Dynomotion Forum

Ashamed to say that I managed to reverse the motor supply input polarity on my SnapAmp board after replacing a relay to my E-stop circuit and heard a pop followed by the dreaded smoke after powering it on. (The popping sound may have been an in-line fuse that blew.)

The smoke appeared to come from the snapamp board from under the kflop and the small indicator lights on the snapamp no longer light up when powered on. However, the kflop board appears to be working fine from what I can tell and I get the "ready" msg when sending the version cmd via the console.

After close inspection of the snapamp board, I am not seeing any signs of failure at any place on the board which is a mystery to me since I heard a small popping sound (though may have been from the inline fuse) and there was a lot of smoke released and so I would expect to see some indication of burning but there isn't any. Same with the kflop board.

Question 1: Can I assume the kflop is not undamaged or is there a chance it is also compromised?

Question 2: Considering the cause of failure, can the snapamp be repaired at this point?

Any help would be much appreciated!

Ok, I did some quick continuity tests on the snapamp board and it looks like the following capacitors have shorts:

C64
C61
C60
C58
C57
C56
C54
C32
C28
C23

Question 3: Does this sound like what could be expected from the damage of reversing polarity to the motor supply inputs?

Ok, I just went through the resistors and found the following ones that weren't to spec:

R8 (??/??) = ~0.245k ohm (code not legible)
R9 (1001/1k) = 0.4k ohm
R17 (1001/1k) = 0.45k ohm

R15 (1002/10k) = 3.896k ohm
R18 (1002/10k) = 3.742k ohm
R19 (1002/10k) = 6.77k ohm
R21 (1002/10k) = 6.77k ohm

R23 (6981/6.98k) = 0.435k ohm
R24 (6981/6.98k) = 0.394k ohm

Question 5: Can you verify the values for these resistors in circuit to know if they are reading correctly? (Not sure what is in parallel, etc)

Question 6: Can you please verify which resistor is located at R8 (marking is no longer legible)?

Question 7: Is there anything else I should be checking for?

Sorry to hear this. Reversing power is one of the worst things that can happen. We don’t find it cost effective to repair boards. Especially in a case where multiple things are likely damaged. If everything isn’t fixed then applying power may cause more damage. The caps probably aren’t shorted rather things connected to the supplies are. Resistors are not likely damaged.

If KFLOP’s LEDs flash then it may be ok. You might toggle JP4’s IO to see if they function.

Contact our Support and we can offer a 20% discount on a replacement SnapAmp.

Thank you for this information Tom, I appreciate it. And thanks for the offer... I will reach out for the discount shortly.

FYI, I've had this board since about 2010 and it's been running great for me over the years so am happy to continue using your products going forward.

The IO's for the JP4 connector on the kflop are all functioning correctly so I think I'm in the clear there. Reaching out now to order a new Snapamp.