I’ve made quite a bit of progress in the last couple of days and I feel like I can see the light at the end of the tunnel. I installed the turret board in the chassis and I finished the wiring on the supply caps, pre-amp, phase inverter, tone controls, ext. amp jack and speaker jacks. I am using a 1/4″ jack for the main speaker out, so I spent extra time with the schematic to make sure I understood what I was doing. The typical standby protection will not be there, since I’m using a 1/4″ jack, so I’ve added a 10W, 470 ohm resistor across the 16 ohm output, similar to what Ampeg did on later B15N’s.
Turret board finally installed in the chassis
I believe all that remains is the input jacks, volume controls, and the last connection of the standby circuit. Before I proceed, I’m going to go back through the amp and double check the wiring I’ve done so far. I’ve tried to do checks as I completed each stage but a recheck certainly can’t hurt.
Well, it’s been awhile but I have finally made a little more progress on the wiring. Besides taking time off to work on a couple of other projects, I also had to get more Teflon wire. While I had plenty of wire here to do this project, I did not have much of a variety of colors. As I got deeper into this project I began to realize that there was a logic (duh!) to the wire colors used in the original amps. In hindsight this seems rather obvious, but as I’ve mentioned before, this is all new to me, and sometimes there are details just staring me in the face that I initially don’t catch. That is the major point of this project though, so I am continuing to learn.
Continuing to wire the board
I am trying to get as much wiring done to the board as I can before I install it in the chassis. I am trying to only do wires that make sense right now. Others, such as some of the control leads, I think will be easier to do after the board is installed.
The “font” used for the Ampeg script logos and Portaflex amplifiers (as shown below) was designed by Henry Konarsky. According to Jess Oliver, Mr. Konarsky was “a good friend, artist and guitar player. He also did several of our catalogs and we kept him in amplifiers“.
Ampeg/Portaflex logos
Here is a scan of a Portaflex cutsheet. One page explains the operation and benefits of the Portaflex design. The second page shows a flowchart for troubleshooting musical instrument amplifiers.
Portaflex cutsheet (PDF)
