Hello prithvi,
Thanks for writing in.
Is it this item? https://www.amazon.com/dp/B0789QVKKF/ref=as_li_tl?tag=proeng-20
When you short output terminals with multimeter probe, there is short circuit current. So it is normal that it sparks.
And voltage drop is also no problem. Please kindly notice you can’t adjust voltge in that case.
For any more questions, please kindly contact us.
Best regards.