McBarry
Well-known member
My IIB 60w rev,non-eq has developed a strange and annoying symptom.
Usually on startup, on clean ch, the amp will sound dull, lifeless.(Bright sw is pulled). It's not dramatic, and it's only really AFTER the treble returns than I can convince myself I'm not dreaming.
After a variable time of 5 to 30mins the treble suddenly returns.
BUT at a gig 2 wks ago it was going OK, and then the treble dropped off AFTER about 1hr playing... It did return, can't recall how long.
What I've done with no improvement: changed V1, V2, power tubes, spray cleaned all pots..
PI is next on the swap-out list.
Has anyone seen this before?
I'm wondering, in no particular order: Bright switch cap failing, bright switch failing, treble cap failing, treble pot failing.
Then I'm wondering coupling cap - bugger to track down though..
Ideas anyone with likely culprits or a debugging technique they've used..???
Thx, Dave
Usually on startup, on clean ch, the amp will sound dull, lifeless.(Bright sw is pulled). It's not dramatic, and it's only really AFTER the treble returns than I can convince myself I'm not dreaming.
After a variable time of 5 to 30mins the treble suddenly returns.
BUT at a gig 2 wks ago it was going OK, and then the treble dropped off AFTER about 1hr playing... It did return, can't recall how long.
What I've done with no improvement: changed V1, V2, power tubes, spray cleaned all pots..
PI is next on the swap-out list.
Has anyone seen this before?
I'm wondering, in no particular order: Bright switch cap failing, bright switch failing, treble cap failing, treble pot failing.
Then I'm wondering coupling cap - bugger to track down though..
Ideas anyone with likely culprits or a debugging technique they've used..???
Thx, Dave
