12000 is cursed
Posted: Fri Jul 24, 2020 10:04 pm
Hey all,
I have built many amps and at least 3 Marshall amps thus far in the past 5 years. I am familiar as to how to build them and typically when built they work immediately and have no issues. I decided to build a 12000 series amp as it was one Marshall I wanted to do but haven't built yet. I got it working and took it to practice and it was producing a smell. It seemed that the PT was getting super hot where I couldn't touch it without feeling like I was going to set my finger a flame.
I decided to move the ground for the heaters to way out under the preamp board and give it a super good connection. I also decided to rebuild the preamp board as my board shipped with the vintage style turrets (even though I didn't order those). I put the modern style turrets and redid the board. I also changed the grid resistors to the 4 5.6k ones attached by wire thinking that the singular 5.6k ones would not be enough. Since I have done that I figured it would work great. All I get is very weak output similar to a dying or dead fuzz pedal. I know it is not the tubes as I have swapped them all out for a known working set from my JTM100. Today I rebuilt the power board replacing the vintage Erie caps with known working F&T 100uf ones. I still get the same result!!! I have been pulling out my hair trying to figure this out because it was working before.
One concern I had was that when I installed the M***** PT that I had to crack some of the goop at the bottom in order to fit it into the chassis as it was a bit big. I realized today the smell I was smelling at my practice a couple of weeks ago was the varnish inside the PT as I saw it on the bias wire. The PT had gotten hot enough to melt some or the varnish maybe?
Also this amp was supposed to have Piher resistors in it but they never showed up due to the mail being absolutely terrible.
I have attached some photos of the amp as it is currently and what it looked like prior with the big blue Eries.
Thanks in need as I feel like throwing this amp in the garbage!!
https://imgur.com/a/9NM3Xg9
I have built many amps and at least 3 Marshall amps thus far in the past 5 years. I am familiar as to how to build them and typically when built they work immediately and have no issues. I decided to build a 12000 series amp as it was one Marshall I wanted to do but haven't built yet. I got it working and took it to practice and it was producing a smell. It seemed that the PT was getting super hot where I couldn't touch it without feeling like I was going to set my finger a flame.
I decided to move the ground for the heaters to way out under the preamp board and give it a super good connection. I also decided to rebuild the preamp board as my board shipped with the vintage style turrets (even though I didn't order those). I put the modern style turrets and redid the board. I also changed the grid resistors to the 4 5.6k ones attached by wire thinking that the singular 5.6k ones would not be enough. Since I have done that I figured it would work great. All I get is very weak output similar to a dying or dead fuzz pedal. I know it is not the tubes as I have swapped them all out for a known working set from my JTM100. Today I rebuilt the power board replacing the vintage Erie caps with known working F&T 100uf ones. I still get the same result!!! I have been pulling out my hair trying to figure this out because it was working before.
One concern I had was that when I installed the M***** PT that I had to crack some of the goop at the bottom in order to fit it into the chassis as it was a bit big. I realized today the smell I was smelling at my practice a couple of weeks ago was the varnish inside the PT as I saw it on the bias wire. The PT had gotten hot enough to melt some or the varnish maybe?
Also this amp was supposed to have Piher resistors in it but they never showed up due to the mail being absolutely terrible.
I have attached some photos of the amp as it is currently and what it looked like prior with the big blue Eries.
Thanks in need as I feel like throwing this amp in the garbage!!
https://imgur.com/a/9NM3Xg9