Help - Marshall clone 18w FOUND IT JTM45 or TMB18 ?
Posted: Sun 04/20/25 6:25 am
Hey everyone,
Yesterday I bought a Marshall-style clone amp that used to belong to someone who sadly passed away. When I first tried it out, the amp worked—although the jumpered channels didn’t function, and the presence pot didn’t seem to do anything. Once I got home and spent more time testing it, I noticed it started making strange noises at higher gain settings, so I decided to open it up.
To my surprise, I found that one preamp tube was missing, and some components were not even connected. There’s also a rear input jack marked “B+” that runs to the presence pot… very strange.
I’ve been trying to find a schematic (the family has no info on the build), and so far the layout seems to be about 70% similar to the Ceriatone 18W TMB clone. The main difference is the front panel, which does not have a master volume but does have a presence pot, more like a JTM-style 18W build.
So now I’m wondering what you all would do in this situation:
Should I keep the Ceriatone TMB circuit but adapt the control layout to work like a JTM45 (e.g., wiring the presence pot as in a JTM)?
Or should I just modify the front panel, add a master volume pot, and stick with the TMB design?
Ideally, I’d like to keep the JTM-style layout if possible, but I’m open to ideas.
Also, have any of you seen a schematic that includes a rear jack labeled "B+" connected to the presence control? That one’s got me scratching my head.
Thanks in advance!
Yesterday I bought a Marshall-style clone amp that used to belong to someone who sadly passed away. When I first tried it out, the amp worked—although the jumpered channels didn’t function, and the presence pot didn’t seem to do anything. Once I got home and spent more time testing it, I noticed it started making strange noises at higher gain settings, so I decided to open it up.
To my surprise, I found that one preamp tube was missing, and some components were not even connected. There’s also a rear input jack marked “B+” that runs to the presence pot… very strange.
I’ve been trying to find a schematic (the family has no info on the build), and so far the layout seems to be about 70% similar to the Ceriatone 18W TMB clone. The main difference is the front panel, which does not have a master volume but does have a presence pot, more like a JTM-style 18W build.
So now I’m wondering what you all would do in this situation:
Should I keep the Ceriatone TMB circuit but adapt the control layout to work like a JTM45 (e.g., wiring the presence pot as in a JTM)?
Or should I just modify the front panel, add a master volume pot, and stick with the TMB design?
Ideally, I’d like to keep the JTM-style layout if possible, but I’m open to ideas.
Also, have any of you seen a schematic that includes a rear jack labeled "B+" connected to the presence control? That one’s got me scratching my head.
Thanks in advance!