[. . . ] A HELPFUL HINT To help protect your SB-220/221 from high voltage current transients, try making and installing a simple HV fuse. [. . . ] Find the HEAVY BLUE HV wire coming from hole "J" of the left side of the rectifier/metering circuit board that goes to the HV feedthrough insulator "CK" to the left of the circuit board. Cut this wire in the middle and solder the ends to the pads on your HV fuse. Take a piece of small wire, about #32 to #36, and solder it between the pads on the fuse. If you do not have the small gauge wire, you can get it from any 110VAC extension cord of the cheap variety ­ ONE strand is enough. [. . . ] This can also be adapted for the SB-200/201. NOTE: A good source of #36 wire is ONE strand from a discarded computer ribbon cable. [. . . ]