Video Board Parts List (3 of 3)
Sheet 3 of Commodore's Display Assembly Component Cross Reference for the Commodore PET 2001 gives items 54 to 70 of the 70-item list: the remaining resistors, the four spark gaps, the two transformers, the regulator, the CRT socket, heatsink hardware, the yoke and the bare PCB, by reference designator, description and Commodore part number. Sheet 1 has the capacitors, diodes and connectors, and sheet 2 the chokes, transistors and first resistors. The scan comes from the zimmers.net Commodore archive, which files it as the parts list for the video board.[1]
Commodore calls this board the display assembly. It runs the monitor from low-voltage AC supplied by the transformer in the case; see Video Board Parts List (1 of 3) for the supplies it generates.
 | The CRT anode runs at about +10 kV from flyback T2, and the tube holds that charge after the machine is switched off. Discharge it before working near it: see CRT Discharge Procedure. Mains voltage is present in the case at the power switch, fuse and transformer primary whenever the PET is plugged in. |
Contents
[edit | edit source]| Item | Ref. des. | Description | Part no. |
|---|---|---|---|
| 54 | R35 | 4.7 kΩ 1/4 W 5 % | 901550-19 |
| 55 | R36 | 560 Ω 1/4 W 5 % | 901550-30 |
| 56 | R38 | 470 Ω 1/4 W 5 % | 901550-58 |
| 57 | R39 | 270 Ω 1/4 W 5 % | 901550-76 |
| 58 | R40 | 220 Ω 1/4 W 5 % | 901550-52 |
| 59 | R42 | 10 Ω 1/2 W 5 % | 901600-14 |
| 60 | R43 | 120 Ω 1/4 W 5 % | 901550-75 |
| 61 | SG1-SG3 | .01 20 % spark gap, Gap-103 | 900040-01 |
| 62 | SG4 | .75 pF spark gap, Gap-R75 | 900040-02 |
| 63 | T1 | Transformer, Marvel M594A1A | 902450-02 |
| 64 | T2 | Transformer, flyback | 902475-03 |
| 65 | VR1 | Voltage regulator | 901527-01 |
| 66 | CRT tube connector | 903150-01 | |
| 67 | Nut, hex, #6-32 (heatsink) | 905950-02 | |
| 68 | Screw, Phillips, #6-32 x .5 (heatsink) | 906610-02 | |
| 69 | Yoke assembly | 320078 | |
| 70 | PCB | 320084-02 |
Reading the sheet
[edit | edit source]T1 is the horizontal driver transformer. The service schematic draws it between driver transistor Q13 and the base of horizontal output transistor Q14 and labels it "Shinwa 902450, Marvel M594A1A". It is not a mains transformer: the PET's mains transformer is in the case.[2][3]
The list calls VR1 only "voltage regulator". The service schematic and the placement drawing both mark it 7812UC, a +12 V regulator.[2][4] Commodore used the same part number, 901527-01, for the MC7812CT on the later C64 B-3 board.[5]
The flyback is listed only by part number. The service schematic and the placement drawing mark it GI 294-7746, with a DOK version as the alternative; the earlier drawing 320032 shows a Zenith flyback, part 93-3195.[2][4][6]
The spark gaps are fitted components. The placement drawing marks SG1-SG3 as 0.01 µF 1.5 kV parts, and the schematic puts SG1-SG3 on the CRT grid connections and SG4 on the cathode drive.[4][2]
Related pages
[edit | edit source]- Video Board Parts List (1 of 3) and Video Board Parts List (2 of 3)
- Video Board Schematic and Schematic Notes for Video Board
- Video Board Parts Layout
- Commodore PET 2001 Capacitor Replacement Guide
- Commodore PET 2001 Service Documentation
Download: parts-6.gif
References
[edit | edit source]- ↑ zimmers.net Commodore archive, /pub/cbm/schematics/computers/pet/2001/ directory listing (retrieved 2026-10-01). Source of parts-4.gif to parts-6.gif ("parts list for the video board").
- ↑ 2.0 2.1 2.2 2.3 Commodore Business Machines, Schematic, Service, Display Circuit for the PET 2001, hosted as File:video-1.gif and described at Video Board Schematic. Shows T1 (Shinwa 902450 / Marvel M594A1A) in the horizontal drive stage, flyback T2 marked "GI 294-7746" with "DOK 902475" as the alternative, spark gaps SG1-SG4, and VR1 marked 7812UC producing +12 V.
- ↑ PET-Shack (P.S. Software House), PET 2001 schematic and data-sheet bundle, c. 1978, hosted at File:PET-Shack PET 2001 Bundle.pdf. Third-party, not a Commodore document. Its "PET console wiring" drawing shows the power switch and a 1.8 A fuse on the transformer primary and a 16.2 V AC winding to the video monitor.
- ↑ 4.0 4.1 4.2 Commodore Business Machines, Display PCB Assembly component-placement drawing for the PET 2001, hosted as File:video-layout.gif and described at Video Board Parts Layout. Marks "VR1 7812 UC" inside heatsink H1 and SG1-SG3 as ".01 µF 1.5 kV" spark gaps.
- ↑ Commodore Business Machines, C64 / C64C Service Manual, March 1992, PN-314001-03, hosted at Commodore 64 / 64C Service Manual. B-3 parts list: VR1 "IC Volt Regulator +12V MC7812CT 901527-01".
- ↑ Commodore Business Machines, drawing 320032 rev A, Display Schematic, hosted as File:video-2.gif and described at Video Board Schematic (Rev 2, 320032).
