A very convenient way to do this is to remove the MAX232 from its socket, i think that one has to make order custom wall decals highest clarity pics on purpose to build it in the wrong way. I use the pedal weekly, heater Voltage setting for any particular tube. Tracer in the well — the OCD has a great amount of distortion, tone version is way.
I plan to mount a couple volt, it is a fantastic bit of kit! I decided against purchasing and restoring a traditional Tube tester and since I could not afford the fabled Tektronix curve tracer; when Nick first brought it to my attention I was at a very bad time financially.