Video Board Parts List (3 of 3)
Sheet 3 of Commodore's Display Assembly Component Cross Reference for the Commodore PET 2001 — the remaining resistors, the spark gaps, the transformers and the regulator. Commodore Business Machines, Inc., Palo Alto, California, scanned at 400 dpi. The list is numbered 1–70 across the three sheets.
"Video board" is this wiki's word, not Commodore's. Commodore calls it the display assembly, and it is the machine's power supply as well as its monitor — the mains transformer, the bridge rectifier, the 4700 µF reservoir, the +12 V regulator, the −30 V and +85 V rails and the flyback are all on it. Anyone looking for the PET 2001's PSU documentation is looking for this board.
 | The display assembly is the PET's power supply as well as its monitor. Mains voltage is present on it whenever the machine is plugged in, the CRT anode runs at roughly +10 kV from flyback T2, and C1 is a 4700 µF reservoir that stores real energy. Read CRT Discharge Procedure before working on this board. |
{{| class="wikitable styled-table" |- ! Ref !! Description !! Commodore part no. |- | R35 || 4.7 k 1/4 W 5 % || 901550-19 |- | R36 || 560 Ω 1/4 W 5 % || 901550-30 |- | R38 || 470 Ω 1/4 W 5 % || 901550-58 |- | R39 || 270 Ω 1/4 W 5 % || 901550-76 |- | R40 || 220 Ω 1/4 W 5 % || 901550-52 |- | R42 || 10 Ω 1/2 W 5 % || 901600-14 |- | R43 || 120 Ω 1/4 W 5 % || 901550-75 |- | SG1–SG3 || 0.01, 20 %, spark gap, Gap-103 || 900040-01 |- | SG4 || 0.75 pF spark gap, Gap-R75 || 900040-02 |- | T1 || Mains transformer — Marvel M594A1A || 902450-02 |- | T2 || Flyback transformer || 902475-03 |- | VR1 || Voltage regulator || 901527-01 |- | — || CRT tube connector || 903150-01 |- | — || #6-32 hex nut (heatsink) || 905950-02 |- | — || #6-32 × 0.5 Phillips screw (heatsink) || 906610-02 |- | — || Yoke assembly || 320078 |- | — || PCB || 320084-02 |}}
Three things this sheet settles.
- VR1 is a 7812. The parts list says only "voltage regulator, 901527-01", but the component-placement drawing at Video Board Parts Layout marks the position "VR1 7812 UC", and the same Commodore part number 901527-01 appears as an MC7812CT in Commodore's later service documentation. The display assembly's regulated output is +12 V.
- The four spark gaps are real components, not board features: SG1–SG3 are 0.01 / 1.5 kV types and SG4 is a 0.75 pF type. They protect against flashover and are easy to mistake for damaged parts.
- The yoke and the bare PCB have their own Commodore part numbers — 320078 and 320084-02 — in the same 320xxx series as the schematics.
Related pages
[edit | edit source]- The other sheets: Video Board Parts List (1 of 3) · Video Board Parts List (2 of 3)
- Video Board Schematic — the circuit these parts sit in, with 14 waveform photographs
- Video Board Parts Layout — where each of them physically is, with a value against every position
- Schematic Notes for Video Board — the oscilloscope settings for those waveform photographs
- Commodore PET 2001 Capacitor Replacement Guide — which takes its display-assembly values from this list
- Commodore PET 2001 Service Documentation · CRT Discharge Procedure · Capacitor Failure Symptoms
Download: parts-6.gif