Editing Commodore PET 2001 Service Documentation

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[[File:Commodore PET 2001 Open.jpg|thumb|400px|A PET 2001-8 with the top raised. The main logic assembly lies flat under the keyboard; the display assembly is mounted on the CRT at the front.]]

Commodore's own service documentation for the '''[[Commodore PET 2001]]''' survives in reasonable completeness. Four documents are hosted here, and together they cover both assemblies inside the machine at component level.

They are the source for every figure on [[Commodore PET 2001 Capacitor Replacement Guide]].

== Parts lists ==

* '''[[:File:Commodore PET 2001 Main Logic Assembly Parts List.pdf|8K Main Logic Assembly Parts Cross Reference]]''' — every component on the system board by reference designator, description and Commodore part number. Carries a text layer.
* '''[[:File:Commodore PET 2001 Display Assembly Parts List.pdf|Display Assembly Component Cross Reference]]''' — the same for the 9-inch monitor and power board, which is also where the machine's mains transformer and reservoir capacitor live.

== Schematics ==

* '''[[:File:Commodore PET 2001 Main Logic Schematic (320008).pdf|Main logic schematic, assembly 320008]]''' — three sheets. Sheet 1 is drawing 320130, ''circuitry common to all PET computers''; sheets 2 and 3 are drawing 320026 and are specific to assembly 320008.
* '''[[:File:Commodore PET 2001 Display Circuit Schematic.pdf|Schematic, Service, Display Circuit]]''' — the monitor and supply board, with the oscilloscope settings for the waveform photographs printed on the drawing.

== The four original board assemblies ==

Commodore's note on sheet 3 of the main logic schematic records that '''all component locations are the same on all four boards'''; only the fitted components differ, and the identifying board number is silkscreened in the upper left corner.<ref name="msch">Commodore Business Machines, ''PET Computer Main Logic'' schematic, drawings 320130 (sheet 1) and 320026 (sheets 2&ndash;3), for board assembly 320008. Hosted here as [[:File:Commodore PET 2001 Main Logic Schematic (320008).pdf]]. Sheet 3 carries Commodore's note that component locations are common to assemblies 320008, 320081, 320132 and 320137.</ref>

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Original PET 2001 ("static") board assemblies'''
! Assembly !! ROMs !! RAM !! Schematic
|-
| '''320008''' || 6540 || 6550 || 320026
|-
| '''320081''' || 2316B || 6550 || 320082
|-
| '''320132''' || 6540 || 2114 || 320130
|-
| '''320137''' || 2316B || 2114 || 320135
|}

All four are variants of the original static board. The later '''2001-N / 3000 / 4000''' dynamic system board is a different design and is not covered by these documents; for those machines see [[Commodore PET 4000 Series]].<ref name="zim">[http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/ zimmers.net Commodore PET schematics index]. Directory listing distinguishing the original 2001 static board from the 2001N/3000/4000 dynamic system board, and naming the four static-board variants and their schematic numbers. A secondary source for the directory structure; the assembly numbers themselves are confirmed by Commodore's own note on the schematic.</ref>

== What these documents establish ==

* The only aluminium electrolytics on the main logic board are '''C7&ndash;C10, 47&nbsp;&micro;F 16&nbsp;V'''. C5, C11, C12 and C13 are 1&nbsp;&micro;F 25&nbsp;V tantalums; C15&ndash;C49 are 0.1&nbsp;&micro;F ceramics.<ref name="mla">Commodore Business Machines, ''8K Main Logic Assembly Parts Cross Reference'' for the PET 2001. Hosted here as [[:File:Commodore PET 2001 Main Logic Assembly Parts List.pdf]]. Gives every component on the system board by reference designator, description and Commodore part number.</ref>
* The 4700&nbsp;&micro;F 25&nbsp;V reservoir is '''C1 on the display assembly''', not on the system board.<ref name="disp">Commodore Business Machines, ''Display Assembly Component Cross Reference'' for the PET 2001. Hosted here as [[:File:Commodore PET 2001 Display Assembly Parts List.pdf]]. Numbered list of every component on the monitor and supply board.</ref>
* The main logic board carries '''no voltage regulator'''. It receives +5&nbsp;V and a +9&nbsp;V unregulated rail from elsewhere in the machine.<ref name="mla" />
* The display assembly generates +12&nbsp;V, a +85&nbsp;V boost rail, &minus;30&nbsp;V and roughly '''+10&nbsp;kV''' for the CRT anode.<ref name="dsch">Commodore Business Machines, ''Schematic, Service, Display Circuit'' for the PET 2001, with the supplementary sheet of oscilloscope settings. Hosted here as [[:File:Commodore PET 2001 Display Circuit Schematic.pdf]]. Shows CR19&ndash;CR22, C1, VR1, the +85&nbsp;V boost and &minus;30&nbsp;V rails, the flyback T2 and the +10&nbsp;kV anode supply, and the deflection yoke figures.</ref>
* The master crystal Y1 is '''8&nbsp;MHz'''.<ref name="msch" />

== The full drawing set, sheet by sheet ==

The same documents are also held here as individual high-resolution sheets, which is the form to cite when you want one specific drawing rather than a whole PDF. Every page says what is on its own sheet and what is not.

=== Main logic assembly ===

* '''[[System Board Parts List (1 of 3)]]''' &mdash; ''Main Logic Assembly Parts Cross Reference'', sheet 1: capacitors, diodes, transistors, connectors and resistors with Commodore part numbers. Establishes that '''only C7&ndash;C10 are aluminium electrolytic''' on the whole board.
* '''[[System Board Parts List (2 of 3)]]''' &mdash; sheet 2, the IC cross-reference: 6502 at UF3, 6520 PIAs at UB8/UG8, 6522 VIA at UA5, and the '''6550-versus-2114 RAM line printed twice''' against the same eighteen positions, which is how Commodore expressed the difference between the board assemblies.
* '''[[System Board Parts List (3 of 3)]]''' &mdash; sheet 3, the remaining ROMs and the socket types. Records a '''revised UH1 ROM''' (6540-019 / 2316B-09, parts 901439-09 / 901447-09) found nowhere else in Commodore's PET 2001 documents held here, and makes plain that the '''6540 is a 28-pin part and the 2316B a 24-pin part'''.
* '''[[2001 Main Logic Assembly]]''' &mdash; the same three sheets as one PDF. The file is byte-identical to [[:File:Commodore PET 2001 Main Logic Assembly Parts List.pdf]].

There is '''no component-placement drawing for the main logic board''' on this wiki. The display assembly has one; the system board does not.

=== Main logic schematics, by board assembly ===

Sheet 1 of every set is the same universal drawing, '''#320130''', ''Circuitry common to all PET computers''. Sheets 2 (Memory Section) and 3 (Video Logic) are the board-specific drawings.

{| class="wikitable styled-table" style="width:100%; text-align:left;"
! Board !! Complete set !! Sheet 2 &mdash; Memory !! Sheet 3 &mdash; Video logic
|-
| '''320008''' || [[Schematic 320026 (Complete, Board 320008)]] || [[Schematic 320026 (Sheet 2 of 3, Board 320008)]] || [[Schematic 320026 (Sheet 3 of 3, Board 320008)]]
|-
| '''320081''' || [[Schematic 320082 (Complete, Board 320081)]] || [[Schematic 320082 (Sheet 2 of 3, Board 320081)]] || [[Schematic 320082 (Sheet 3 of 3, Board 320081)]]
|-
| '''320132''' || [[Schematic 320130 (Complete, Board 320132)]] || [[Schematic 320130 (Sheet 2 of 3, Board 320132)]] || [[Schematic 320130 (Sheet 3 of 3, Board 320132)]]
|-
| '''320137''' || [[Schematic 320135 (Complete, Board 320137)]] || [[Schematic 320135 (Sheet 2 of 3, Board 320137)]] || [[Schematic 320135 (Sheet 3 of 3, Board 320137)]]
|}

Circuits marked with an asterisk on sheets 2 and 3 are annotated '''"all ckts marked * are for BC machine only"''' &mdash; the business-keyboard variant.

=== Display assembly (the monitor ''and'' the power supply) ===

Commodore calls this the '''display assembly'''; several page titles here call it the "video board". It carries the mains transformer, the bridge, the 4700&nbsp;&micro;F reservoir, the +12&nbsp;V regulator, the &minus;30&nbsp;V and +85&nbsp;V rails and the flyback, so it is where a PET power-supply fault lives.

* '''[[Video Board Parts Layout]]''' &mdash; ''Display PCB Assembly'', the '''component-placement drawing, with a designator and a value against every fitted position'''. The most directly useful document of the set: it identifies a part without tracing the circuit. It is also the drawing that settles '''VR1 = 7812''' and '''C22/C27 = 3.3&nbsp;&micro;F''', and it documents the '''TIP-55A substitution for Q14'''.
* '''[[Video Board Schematic]]''' &mdash; ''Schematic, Service, Display Circuit'', with '''fourteen waveform photographs''' and five service notes (R20 mounts perpendicular for screwdriver adjustment; R9 is at the rear on a 2-inch shaft; Molex 09-64-1021 and 09-64-1061 board connectors; parenthesised numbers are the DOK flyback version).
* '''[[Schematic Notes for Video Board]]''' &mdash; the '''oscilloscope settings for those fourteen photographs'''. Volts and time per division for each, and the only absolute amplitude Commodore published for any of them: '''picture 9, 11.6&nbsp;V peak'''. The schematic and this supplement are useless apart.
* '''[[Video Board Schematic (Rev 2, 320032)]]''' &mdash; Commodore drawing '''#320032 rev A''', ''Display Schematic'', drawn 3-9-76, last revised 6-15-77.
* '''[[Video Board Schematic (Rev 3, 320033)]]''' &mdash; Commodore drawing '''#320033 rev P''', size D, ''Schematic, Display Circuit'', engineering-approved 29 June 1978, next assembly #320012.
* '''[[Video Board Parts List (1 of 3)]]''' &middot; '''[[Video Board Parts List (2 of 3)]]''' &middot; '''[[Video Board Parts List (3 of 3)]]''' &mdash; ''Display Assembly Component Cross Reference'', items 1&ndash;70 with Commodore part numbers, including the yoke assembly (320078) and the bare PCB (320084-02).

'''"Rev 2" and "Rev 3" in those two page titles are this wiki's numbering, not Commodore's.''' 320032 and 320033 are different drawing numbers carrying their own revision marks A and P; they are not two revisions of one drawing. Check the number against your own machine's paperwork, or the values on your own board.

== Other PET material hosted here ==

* '''[[Schematic 320130 (Sheet 1 of 3, Static PET)]]''' &mdash; Commodore drawing 320130 sheet 1, ''PET Computer Main Logic, circuitry common to all PET computers'', as a single image. The 6502 at F3, both 6520 PIAs, the 6522 VIA, the three MC3446 IEEE-488 transceivers at A7&ndash;A9, the LM555 retrace timer at E9, the cassette drive circuitry and the keyboard pull-ups. No regulator: the board takes +5&nbsp;V and +9&nbsp;V unregulated from elsewhere.
* '''[[PET Shack Service Bundle]]''' &mdash; a 37-page '''third-party''' compilation sold by PET-Shack of Mishawaka, Indiana. Not Commodore documentation, and secondary to the parts lists above, but it carries things Commodore's own PET 2001 documents here do not: an errata sheet against the published schematics, the cassette deck circuit with values, a capacitors sheet including a '''0.0047&nbsp;&micro;F 1&nbsp;kV''' part, the TIP29/TIP30 supply pass transistors, and manufacturer data sheets for the 6550, the Synertek 6502/6520/6522 and the MC3446 bus transceivers.

== Related pages ==

* [[Commodore PET 2001]] &middot; [[Commodore PET 2001 General Maintenance]] &middot; [[Commodore PET 2001 Troubleshooting]] &middot; [[Commodore PET 2001 Capacitor Replacement Guide]]
* [[Commodore PET 4000 Series Technical Manual]] &mdash; P/N 990438, the ''universal dynamic PET'' board drawing 8032090, which covers the 8032, 4032, 4016 and SuperPET 9000

== References ==

<references />

[[Category:Commodore Documentation]]
[[Category:Commodore Technical Manuals]]