‘77 Marshall 2203 - Currently has 6L6s?

[silverwulf]

Just picked up a ‘77 Marshall JMP 2203. It came loaded with 6L6s, specifically the Sovtek 5881/6L6 variant. Given it wouldn’t have come with 6L6s originally, was curious to get any insight if you think it was converted over properly to use 6L6s, or if a prior owner just stuck them in. Thanks!

IMG-3349 hosted at ImgBB

Image IMG-3349 hosted in ImgBB

ibb.co

IMG-3350 hosted at ImgBB

Image IMG-3350 hosted in ImgBB

ibb.co

 

[Purgasound]

Looks like you may have 180K bias feed resistors. They are normally 220K for EL34 based amps. They would still work in an EL34 circuit but they are Piher's so they might be original. All of the preamp and power tubes sockets have been changed out. Get rid of those diodes on the power tube sockets and double check the wiring on them.
Replace those filter caps too. It always blows my mind that people will perform extensive work on an amplifier and defiantly refuse to change the only parts that undeniably go bad with age.
Cheers