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Schematic Notes for Video Board

From RetroTechCollection

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

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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

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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.

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

Download: notes-2.gif

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