Philips P2000C General Maintenance
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Philips's System Reference and Service Manual gives the safety rules, removal procedures and adjustments for the Philips P2000C. The power supply and the monitor are units to be replaced, not repaired, but the manual explains how to remove them, how to set the monitor up and how to adjust the floppy controller on the mainboard.[1][2][3] A restoration report by Tony Duell on the cctalk mailing list adds what a badly stored machine needed.[4]
Safety
[edit | edit source]| Where | Warning |
|---|---|
| Whole machine | Remove the mains connector from the rear before taking the cover off or doing any servicing, and allow the safety wait time. The P2000C must not be run with the cover off. |
| Mains plug | The mains filters keep a high voltage across the plug pins for some time if the plug is pulled while the machine is on. Always switch off before removing the mains plug. |
| Power supply | Up to 800 V near the power transistor, including its heat sink; more than 42 V at other points in the unit. |
| Monitor | The CRT board runs at 700 V and the anode can stay charged after switch-off. Remove the anode cap carefully and discharge the anode to ground. The tube is an anti-explosion type, but any damage to it is dangerous. |
| Earthing | The P2000C is Class I equipment and must be connected to an earthed mains supply; all units in a system need a common ground. |
For the general method see CRT Discharge Procedure.
Opening the case
[edit | edit source]- Disconnect the mains cable, the keyboard and any peripherals, take the diskettes out of the drives and the storage compartment, and remove the carrying strap.[5]
- Remove the four screws marked A in View 1 and lift the cover off carefully, without damaging the screening springs.[5]
- Before refitting the cover, check that no wiring can be trapped.[5]
Removing units
[edit | edit source]| Unit | Procedure |
|---|---|
| Mainboard and terminal board | Both are on a sub-chassis. Remove three screws (View 2) and loosen four (View 3), withdraw the sub-chassis slightly and disconnect the five mini-match connectors, the disk drive connectors and the sixth mini-match connector. To change the mainboard, take off the rear mask first (six cross-point screws). |
| Terminal board | Disconnect the link to the mainboard, remove four screws with lock washers (View 4) and slide the board off its lugs. Refit the lock washers: they also bond the board electrically. |
| Disk drives | Remove the strengthening strip (three screws, loosen two), close the drive levers, remove the retaining clips and the cover plate, and disconnect the signal and power connectors as the drives come out. |
| Monitor | Remove the strengthening strip, take the drive power cable out of its clips at the back of the monitor, disconnect the video connector, remove two screws and lift the monitor out. |
| Front mask | Loosen four screws, remove one, ease the mask forward and unclip the power distribution panel, starting with the clip nearest the power LED. |
| Power supply | Remove the strengthening strip and the front mask, loosen two screws, lift the unit out of its supports and unplug its two connectors. The fuse holder can only be reached with the unit out. |
| Mains switch and socket | Remove the power supply first. The switch is held by two upper screws; the two lower ones are preset to line it up with the front mask. Both are soldered in. |
| Keyboard | Remove three screws from the back of the housing, then free the top cover by pressing down on three points (View 12) while lifting its front edge. The board sits in a groove at the front and is held by two screws at the back. |
Disk drives
[edit | edit source]The P2000C was fitted with TEAC FD 55A (160 KB) or FD 55F (640 KB) drives; the manual expected them to be superseded by the FD 55A(L) and FD 55F(L).[10] Each drive needs three jumpers: HM (head load with motor on), one of DS0 to DS3 for the drive number (DS0 is drive 1), and ST (48 tpi) or WT (96 tpi) to match the drive. The last drive in the internal chain, and the last drive in any external chain, must carry the pull-up resistor network.[7] The drives are supplied for service without their locating pins, so take the pins out before sending a drive away.[7]
In Tony Duell's machine both FD 55A drives had rough spindle bearings. He fitted new ball races to the spindle motors and to the rear of the stepper motors, and found both spindles running at about 295 rpm instead of 300, which he corrected with the potentiometer on the motor board.[4] The drive data in the manual give 300 rpm, with long-term speed variation under ±1.5 %.[11] See also Floppy Drive Repair.
Adjustments
[edit | edit source]Monitor
[edit | edit source]Philips says the monitor adjustments are for a qualified technician. The module needs 12 V ±0.2 V and TTL video and sync signals.[12]
| Adjustment | Control | Method |
|---|---|---|
| Horizontal frequency | VR501 | Disconnect the input signal, couple a frequency counter loosely to the horizontal output, set 15.67 kHz |
| Vertical frequency | VR401 | With the input connected, set for a stable picture |
| Horizontal width | L502 | With a full-dots pattern, set the width to 165 ±2 mm |
| Vertical height and linearity | VR402, VR403 | With a cross-hatch pattern, set the height with the best linearity |
| Centring | Centring rings on the deflection yoke | Rotate the two rings. If the picture is tilted, loosen the yoke screw, turn the yoke, push it fully home and retighten. |
| Focus | VR203 | Best focus over the display area |
Leave the sub-magnets on the deflection yoke alone; they correct linearity and raster distortion.[2] The maintenance program's screen adjustment test divides the screen into 16 equal parts with lines of the letter O and inverts the edges, which is a convenient pattern for these adjustments.[13]
Floppy controller VCO
[edit | edit source]The data separator on the mainboard has a VCO whose centre frequency is set with potentiometer 4712, and a monostable set with potentiometer 4713.[3]
- With power on the mainboard, connect pin 3 of item 7415 (74LS221) to ground.
- Measure the frequency at TP2 and set it to 500 kHz ±1 % with potentiometer 4712.
- Remove the link from pin 3 to ground.
- Look at TP1 on an oscilloscope and set the time between the falling and rising edges as near to 1 µs as possible with potentiometer 4713.
Tony Duell found the VCO slightly off on his machine and reset it to this procedure.[4]
Mains input voltage
[edit | edit source]The power supply runs on 90 to 140 V or 180 to 264 V. To change range, remove the unit with the power cable disconnected and move the flying lead to the input pin marked 115V or 230.[1]
Storage and operating conditions
[edit | edit source]| Condition | Storage | Operating |
|---|---|---|
| Temperature | -40 to 70 °C | 10 to 35 °C |
| Temperature, disks | 10 to 52 °C | |
| Rate of temperature change | 5 °C per minute | 5 °C per minute |
| Relative humidity | 5 to 95 % | 20 to 80 % |
Philips adds that the P2000C should not be left in strong sunlight and that the figures assume no condensation.[14]
Restoration notes
[edit | edit source]Tony Duell's P2000C had been stored badly. The terminal board at the back and the disk drives were the worst affected; the aluminium chassis had surface corrosion and the screws were rusty, but they are standard M3 and M4 sizes.[4]
| Part | What he found | What he did |
|---|---|---|
| Mains switch | Would not latch; a tiny internal spring had corroded and fell apart | Fitted a substitute switch on a new bracket |
| Keyboard cable | Insulation crumbling, green corrosion on the wires | The right-angled 6-pin DIN plugs are not moulded, so he rewired them with 6-core screened cable |
| Keyboard | Remains of spilt coffee | Took the keycaps off and cleaned it |
| Carrying strap | Missing; its end fittings also hold the keyboard over the front panel for carrying | Made new end fittings from 30 mm by 2 mm aluminium strip |
Philips's pinout for the keyboard cable (DIN 45 322, 240°) is 1 count, 2 vertical sync, 3 LED, 4 light pen, 5 +12 V, 6 ground, with the screen to ground.[15]
Related pages
[edit | edit source]- Philips P2000C
- Philips P2000C Troubleshooting Guide
- Philips P2000C Capacitor Replacement Guide
- Philips P2000C Documentation
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.1, Power Supply, pp. 1-1 to 1-3: servicing by replacement, safety precautions, input voltage selection (PDF pages 77 to 79). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 2.0 2.1 2.2 Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.5, Monitor, pp. 1-1 and 1-2: general and safety precautions (PDF pages 225 and 226). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 3.0 3.1 3.2 Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.2, Mainboard, Flexible Disk Controller, pp. 11-3 and 11-5, including 3.4, Adjustment of VCO Middle Frequency (PDF pages 135 and 137). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 4.0 4.1 4.2 4.3 4.4 Tony Duell, "Philips P2000C restoration", cctalk mailing list, 24 January 2023. https://classiccmp.org/mailman3/hyperkitty/list/[email protected]/thread/7GSGD5RFZOGGJPR6SLJM5HECQZHT6UDE/
- ↑ 5.0 5.1 5.2 5.3 5.4 Philips, P 2000 C System Reference and Service Manual, Part 4, section 4.1, Removal and Replacement, pp. 1-1 and 1-2: general warning, cover, mainboard and terminal board (PDF pages 255 and 256). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, 5103 993 30422, 1984, Part 2, section 2.2, pp. 1-2 and 1-5: earthing and safety (PDF pages 66 and 69). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 7.0 7.1 7.2 Philips, P 2000 C System Reference and Service Manual, Part 4, section 4.1, pp. 1-3 and 1-4: mainboard, flexible disk drives, jumpers and pull-up resistors, monitor (PDF pages 257 and 258). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Part 4, section 4.1, pp. 1-5 and 1-6: front mask, power supply unit and fuse, mains switch, mains socket, distribution panel, keyboard cable (PDF pages 259 and 260). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Part 4, section 4.1, p. 1-8: keyboard (PDF page 262). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.6, Disk Drives, p. 1-1 (PDF page 229). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.6, Disk Drives, p. 1-2, disk rotation mechanism (PDF page 230). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 12.0 12.1 Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.5, Monitor, pp. 1-2 and 1-3: adjustments (PDF pages 226 and 227). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Appendix C, Maintenance Facilities, p. C-20, 4.1.4.4, Screen Adjustment Test (PDF page 354). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ 14.0 14.1 Philips, P 2000 C System Reference and Service Manual, Part 2, section 2.2, pp. 1-6 and 1-7, environmental conditions and table 1.1 (PDF pages 70 and 71). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.
- ↑ Philips, P 2000 C System Reference and Service Manual, Part 3, section 3.4, Keyboard, p. 1-2, cable pinning (PDF page 222). Hosted as File:Philips P2000C System Reference and Service Manual.pdf.