04-03-2017, 08:33 AM
Just joined the forum and thought I'd introduce myself and my project(s). I recently brought an original B-25 back into service – my first attempt at tube amp repair, and it went pretty well (apart from a hum I’m still trying to trace). Now I decided to tackle the other, more complicated project in my basement, a 1971 V4-B.
This thing probably lived a hard life before I took it in - dirty, road worn, zero ink left on the face plate but surprisingly original inside. What took it out of service was that it blows fuses (not right away, but after playing for a few minutes). Inside, it looks like the only components that have ever been replaced were one of the rectifier diodes, one resistor (R54), and the power cord. So I figured it was time for a more complete refresh.
I ended up buying the power supply kit from Fliptops, along with some fresh diodes, and placed an order with Mouser for new plate and screen grid resistors, bias resistor/trimpot, couple other odds and ends. Installed the kit this weekend, and now I'm waiting for the Mouser order to arrive. While I wait, I thought I'd share a couple pics - hoping to get a little reassurance that the filter caps look wired correctly? Mostly concerned with C18 and C20. I think I kept the connections in line with the stock setup...
Two questions, while I'm at it...
1. Fly back diodes. I know there is some debate on their usefulness. I bought replacements, but now I'm wondering if I should just remove them. Do I really just snip them out, with no other wiring rerouting?
2. The new power cord is grounded, so assume this makes the polarity switch useless? I noticed that the death cap is still there - can this just be snipped out as well? Any wiring rerouting necessary?
Anything else I should be thinking about updating while I'm under the hood?
Thanks all.
This thing probably lived a hard life before I took it in - dirty, road worn, zero ink left on the face plate but surprisingly original inside. What took it out of service was that it blows fuses (not right away, but after playing for a few minutes). Inside, it looks like the only components that have ever been replaced were one of the rectifier diodes, one resistor (R54), and the power cord. So I figured it was time for a more complete refresh.
I ended up buying the power supply kit from Fliptops, along with some fresh diodes, and placed an order with Mouser for new plate and screen grid resistors, bias resistor/trimpot, couple other odds and ends. Installed the kit this weekend, and now I'm waiting for the Mouser order to arrive. While I wait, I thought I'd share a couple pics - hoping to get a little reassurance that the filter caps look wired correctly? Mostly concerned with C18 and C20. I think I kept the connections in line with the stock setup...
Two questions, while I'm at it...
1. Fly back diodes. I know there is some debate on their usefulness. I bought replacements, but now I'm wondering if I should just remove them. Do I really just snip them out, with no other wiring rerouting?
2. The new power cord is grounded, so assume this makes the polarity switch useless? I noticed that the death cap is still there - can this just be snipped out as well? Any wiring rerouting necessary?
Anything else I should be thinking about updating while I'm under the hood?
Thanks all.