viper chips commonly explode in amstrad sky digiboxes as well, normally caused by over current due to failing hard drives trying to pull so much power. you could replace the chip, but, there will probably also be the photo transistor blown, the limiting resistors, switching transistor, fuse (if fitted) and possibly some of the lower end electrolytic capacitors (if the caps havent gone at this stage, theyre due to go)
While it is possible to repair this (i repair digibox PSU boards at component level) tbh youd be better off getting a complete new PSU board and swapping them over (and checking your HDD)