Sharp BO-A300 Service Manual
The Sharp BO-A300 Service Manual is Sharp Corporation's 38-page service manual for model BO-A300, the original Apple Newton MessagePad (Apple model H1000), which Sharp built for Apple. The circuit diagram is dated 24 May 1993 and headed "Junior-1", the name the manual also uses for the board.[1] Several passages are marked "Pending" or "based on the third trial model", so parts of it describe pre-production hardware.
Contents
[edit | edit source]Page numbers are PDF pages; the printed page number is one less.[1]
- Contents (p. 1)
- Chapter 1, Hardware specifications (p. 2): ARM610 at 20 MHz from a 40 MHz oscillator; 336 × 240 display, 100.77 × 71.97 mm; 640 KB RAM; 4 MB ROM; one-way infrared at up to 19,200 bit/s over 8–80 cm; RS-422 serial at up to 2 Mbit/s on an 8-pin mini-DIN; 68-pin PCMCIA 2.0 slot for Type 1 or 2 cards; CR2032 backup cell; four AAA cells (6 V) or NiCd pack; AC adapter 7 V DC, 500 mA; 181.5 × 111.5 × 27.8 mm; about 440 g with batteries
- Chapter 2, Hardware description (pp. 3–16): block diagram, memory map, chip selects, power system diagram, the ARM610, the ASIC and its pin list, the Z85C30 serial controller, LTC902 line driver, AD7880 A/D converter, SC3611 LCD voltage controller, the 5 V power circuit, the low-battery circuit (IC23), the tablet circuit, the PCMCIA interface
- Chapter 3, Notes for servicing (p. 17): battery gauge; replacing the main and backup batteries with the orange slide switch
- Chapter 4, Disassembly and assembly (pp. 18–22): screws A to D, the IR filter, speaker leads, the 40-pin connector, the 68-pin card eject unit, chassis A and B, reassembly notes
- Chapter 5, Diagnostics (pp. 23–29): pages printed sideways
- Chapter 6, Troubleshooting (pp. 30–36): overcurrent, the "system doesn't start" flowchart, the power-on circuit sequence, and assembly notes for the IR unit, NiCd detection switch, jacks, thermistor, crystal, electrolytic capacitors and coils
- Chapter 7, Circuit diagram (pp. 37–38)
What it settles
[edit | edit source]- The H1000's power-on sequence: IC21 (R55RMSH45B) supplies +5 V once the input reaches 3 V; the ASIC starts the 32.768 kHz crystal and raises DC ON; IC23 flags BAT FAULT below 3 V and IC21 flags VCC FAULT at 4.5 V or less (pp. 15, 32).
- The capacitor values used on the Apple Newton MessagePad Capacitor Replacement Guide: C1 100 µF, C51 3.3 µF 35 V, C59 33 µF 16 V (pp. 37–38).
- Soldering limits: 300 °C for 5 seconds on the crystal and thermistor; 320 °C for 5 seconds on electrolytic capacitors, coils and the speaker leads (pp. 19, 35).
What this manual does not contain
[edit | edit source]There is no parts list and no parts layout drawing, although the contents page promises one. The circuit diagram is a fold-out scanned in two halves, and its lower edge is cut off, so the bottom of the power supply and memory section is missing. It covers only the BO-A300 (Original MessagePad and MessagePad 100); the 110 and later models are different boards.[1]
Pages that cite this document
[edit | edit source]- Apple Newton MessagePad
- Apple Newton MessagePad General Maintenance: batteries and disassembly
- Apple Newton MessagePad Troubleshooting Guide: the flowchart and circuit sequence
- Apple Newton MessagePad Capacitor Replacement Guide: capacitor values
Download: Sharp BO-A300 Newton MessagePad Service Manual.pdf
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Sharp Corporation, Service Manual, Model BO-A300. Hosted as File:Sharp BO-A300 Newton MessagePad Service Manual.pdf. Re-encoded from the Internet Archive scan omp-service-manual (OMPRepairManual.pdf) as greyscale at the scan's 300 dpi; no pages removed.