Hello Esands
Malta calling here.... I am experiencing the exact problem and symptoms with my set up and am very interested yo know the ''Source of fault and the 'Corrective measure' taken to rectify your problems.
I am an engineer so i do understand a level of technology, however with electronics this is somewhat virtual to diagnose. The bigger issue is that Malta is a small island, and although there is a LINE 6 agent, they would not have Line 6 trained techy's and the number of units on the island is low for repair experiences.
So.... my set up is .... Spyder IV 120W + FBV shortboard connected by Cat5 & J45's + Ibanez guitar + Brian May Treble Booster. I have been using this set up for the best of 5 years without a hitch. I have implemented most of the corrections that you listed, namely:
- New instrument cable
- Removed foot-board
- Reset amp to factory defaults
- Made sure firmware was up-to-date
- Tried different guitars
- Tried different patches and amp models
- Tried different volume and gain levels.
There is one action you did not mention. I opened the FBV shortboard and cleaned the white round reflector placed on end of the 'Plunger under foot-board'. This is the one that regulates the height above the 2 electronic eyes on the circuit board. I suspected that some oil or dirt could have effected the interaction of white round reflector. Note: the oil came from a little lubricant i put in the screws seating the footpedal to the unit.
The incidence of intermittent volume/sputtering originally started after a period of warming up but came and went on its own accord. Just no rule to it.
After all the actions , it has somewhat reduced but have to admit it does still happen.
CAN YOU LET ME KNOW OF A PERMANENT FIX THAT YOU HAVE IMPLEMENTED FROM YOUR EXPERIENCE.
Thanks & regards from Malta
Matthew Joslin
https://www.youtube.com/channel/UClWeMjPyvDkdpgNxPgmn7fQ