The wire with the black tape is connected to ground. The other wire is connected to the error amplifier and is where the offset voltage from my DAC board is connected to through a 50k resistor. The connection is to U31 pin 2 which is the 8 pin part. The wire at the top is where I clipped to. The picture isn't the best, the end I clipped to is resting against another pin which makes it less clear. This picture shows the wires connected to the DAC board (2.6K) . I used limits of 5V and 6V around the nominal value of 5.5V.
Feel free to contact me, David Gesswein firstname.lastname@example.org with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with. I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation.
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