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Schematic Notes for Video Board

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Supplement to Schematic for Display Circuit — Commodore Business Machines, Inc. A single typed sheet giving the oscilloscope settings for each of the fourteen waveform photographs printed on the Commodore PET 2001 display circuit schematic.

This is not a set of notes about the video board. It is one specific thing: the vertical sensitivity and timebase that go with each numbered waveform photograph on Video Board Schematic. Without it, those photographs cannot be compared against a real measurement, because the scale they were taken at is not printed beside them. The two documents are useless apart.

The settings, as printed

Picture Vertical Timebase Note
1 1 V 5 ms
2 5 V 2 ms
3 1 V 20 µs
4 10 V 0.5 ms
5 0.2 V 0.2 ms
6 5 V 5 ms
7 0.5 V 5 ms
8 0.5 V 20 µs
9 0.5 V 20 µs 11.6 V peak
10 0.2 V 20 µs
11 5 V 20 µs
12 1 V 20 µs
13 20 V 20 µs
14 5 V 5 ms

Commodore's sheet writes these as "mil sec" and "micro sec"; they are milliseconds and microseconds per division, and the voltage figures are volts per division. Picture 9 is the only one with an absolute figure against it: 11.6 V peak. That is the single measurable number in the document, and it is the only amplitude Commodore published for any of the fourteen test points.

What it does not contain

It does not say where each photograph was taken — the numbered test points are on the schematic itself, not here. It carries no component values, no rail voltages and no fault information.

 
Commodore's Supplement to Schematic for Display Circuit — the oscilloscope settings for the fourteen waveform photographs.

Download: notes-2.gif

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