FrankieSixxxgun
03-31-2009, 11:18 AM
I'm working with a JCM 900 4100 head for a friend. He gave it to me with a blown output tube so shorted that it wouldn't even light the heater, so I biased in a set of JJ 6L6's. I was able to play the amp all day and night, even Hot Plated on 10, with no problems through my JCM 900 1936 cabinet (8 ohms). Gave the amp back to him, he blew the OT fuses immediately. Brought it back to me, replaced the fuses, plugged it into my cabinet, wailed for another 2 hours and never gave up the ghost. He takes it home, plugs it in, blows the fuses almost immediately.
Here is the only variable we're changing: the cabinet. He's plugging into a 4x12 at 16 ohms, I'm in a 2x12 at 8 ohms. I'm thinking he's got a blown/shorted/arcing winding in the OT, but it's above the 8 ohm tap, so it's only prominent when we set the amp to 16 ohms. Does that sound right? Anything else (read: cheaper) I should check/replace first?
Also, I found a Heyboer JCM 900-style laydown tranny for $105 + $15 shipping at thevintagesound.com. That a good deal? Anywhere else I should buy? He's a shredder type player, think he'd be better springing for the MM?
Here is the only variable we're changing: the cabinet. He's plugging into a 4x12 at 16 ohms, I'm in a 2x12 at 8 ohms. I'm thinking he's got a blown/shorted/arcing winding in the OT, but it's above the 8 ohm tap, so it's only prominent when we set the amp to 16 ohms. Does that sound right? Anything else (read: cheaper) I should check/replace first?
Also, I found a Heyboer JCM 900-style laydown tranny for $105 + $15 shipping at thevintagesound.com. That a good deal? Anywhere else I should buy? He's a shredder type player, think he'd be better springing for the MM?