HI all. I just registered for this site and am new to guitar pedal building hobby. Partly for myself, and partly for my daughter and her band to try out new sounds. I am practicing good soldering technique and learning breadboarding and schematic reading. I enjoy the research, parts hunt, soldering, and assembly, but not intending to make my own PCBs. I bought a few pedal PCBs from online vendors.
Anyway, my question has to do with a broken amp I recently bought. It's a Fender Champion 30 (non-DSP), from the mid-late 90's. It's a nice looking cabinet with a 10" speaker, and I would love to use it as my test platform while breadboarding or building pedals. So really just want a nice clean sound to use as a pedal platform.
I had typed up a few paragraphs of what I went through in trying to diagnose what's wrong with the amp, but it's besides the point. I found that almost every pot solder joint was broken and the PCB is a bit warped and flimsy and the traces very fragile. There is evidence of previous (attempted?) repairs. Given that the IC (TD1514A) and plastic PCB-mounted pots are long since discontinued and impossible to find, I think I'd rather put the effort into replacing the PCB with something better.
Specifically, I am interested in using Rod Elliot's pre-amp and power board PCBs from 100 Watt Guitar Amp (Mk II), along with the Fender cabinet, 8ohm speaker, and transformer, using threaded metal jacks and pots mounted to the faceplate. The 100W is certainly overkill for my need. I'd be happy with 20W-50W, but that leads me to a couple of questions about his project.
A couple of initial questions. He suggests using a toroidal transformer, but that a conventional transformer could be used if it supplies no more the 25-0-25 output. According to the Fender service manual schematic, the one I have (Fender part 033613) should be providing 20.3-0-20.3. However he also says "The transformer rating should be 150VA (3A) minimum" and mine appears to be 120VA (1A/250V 5mm fuse). In some cases he says you can substitute this or that, with an impact on the overall output, but I am not so well versed in electronics. In this case he clearly states a minimum, so I'll need to find a new transformer? Also, for the speaker, the project is designed for 4ohm output, but could I use the old 8ohm speaker? (please school me, I am trying to learn)
Any thoughts, gotchas, or better alternatives? Will this work? Many thanks for any input,
Ken
Anyway, my question has to do with a broken amp I recently bought. It's a Fender Champion 30 (non-DSP), from the mid-late 90's. It's a nice looking cabinet with a 10" speaker, and I would love to use it as my test platform while breadboarding or building pedals. So really just want a nice clean sound to use as a pedal platform.
I had typed up a few paragraphs of what I went through in trying to diagnose what's wrong with the amp, but it's besides the point. I found that almost every pot solder joint was broken and the PCB is a bit warped and flimsy and the traces very fragile. There is evidence of previous (attempted?) repairs. Given that the IC (TD1514A) and plastic PCB-mounted pots are long since discontinued and impossible to find, I think I'd rather put the effort into replacing the PCB with something better.
Specifically, I am interested in using Rod Elliot's pre-amp and power board PCBs from 100 Watt Guitar Amp (Mk II), along with the Fender cabinet, 8ohm speaker, and transformer, using threaded metal jacks and pots mounted to the faceplate. The 100W is certainly overkill for my need. I'd be happy with 20W-50W, but that leads me to a couple of questions about his project.
A couple of initial questions. He suggests using a toroidal transformer, but that a conventional transformer could be used if it supplies no more the 25-0-25 output. According to the Fender service manual schematic, the one I have (Fender part 033613) should be providing 20.3-0-20.3. However he also says "The transformer rating should be 150VA (3A) minimum" and mine appears to be 120VA (1A/250V 5mm fuse). In some cases he says you can substitute this or that, with an impact on the overall output, but I am not so well versed in electronics. In this case he clearly states a minimum, so I'll need to find a new transformer? Also, for the speaker, the project is designed for 4ohm output, but could I use the old 8ohm speaker? (please school me, I am trying to learn)
Any thoughts, gotchas, or better alternatives? Will this work? Many thanks for any input,
Ken
I just found that the project is spec'd for 100W at 4ohm, 60W at 8ohm, so that answers that question about using the old speaker. 👍
And now I have discovered Rod Elliott has an updated project "P215" which is a 40W guitar amplifier. Even better!
https://sound-au.com/project215-p27-revisit.htm
But for this project, it sounds like my current transformer will be too much -- P215 specs output of 15-0-15 max.
https://sound-au.com/project215-p27-revisit.htm
But for this project, it sounds like my current transformer will be too much -- P215 specs output of 15-0-15 max.
If you are using the original transformer and load impedance, power output will be like the original, NOT the 100W that Rod got with more V and A. And won't blow-up.
Self report your first post clicking the small blue circle bottom left and ask a Moderator to move this thread from "Solid Stare" which here means "High Fidelity amplifiers" to "Musical instruments and Amplifiers" where it belongs.
You´ll get way more answers there.
Build the 100W amp BUT feed it from the transformer you already have, also use your current speaker.
It won´t put out 100W , you will have the same power as the original Fender amp, but Rodd Elliott´s will work fine, and with ease.
You´ll get way more answers there.
Build the 100W amp BUT feed it from the transformer you already have, also use your current speaker.
It won´t put out 100W , you will have the same power as the original Fender amp, but Rodd Elliott´s will work fine, and with ease.