IBM PS2 Model 30 Schematics

The PS/2 Model 30 schematic set is eight sheets of circuit diagrams for the PS/2 Model 30 (8530) planar, Revision 3, dated 9 June 1991.

These sheets are not an IBM publication. Every title block carries the name Maintenance Information Technologies and the words "COPYRIGHT APPLIED FOR", together with this notice:

"Servicing of any electronic product should only be performed by qualified personnel. This drawing and information has been Copyrighted by the company listed. Its content has been sold for the unlimited use to you. The only restrictions are that it not be copied for republication or distribution outside your company. No patent liability is assumed with respect to the use of information contained herein. Maintenance Information Technologies believes the information herein to be correct. We are not responsible for any typographical errors; no direct or implied warranty is made to its accuracy. Specifications subject to change without notice."

Maintenance Information Technologies was a third-party publisher of service schematics for the independent repair trade in the late 1980s and early 1990s. IBM itself never published a PS/2 schematic.

What it contains

Eight sheets, each titled "PS/2 30":

1. BUSS & I/O
2. CPU
3. MEMORY
4. PRINTER I/O
5. SERIAL I/O
6. DISK I/F & RTC
7. VIDEO INTERFACE
8. DMA INTERFACE

The drawings carry real component designators and real values — U-numbers, RP resistor packs, discrete R and C values, connector designators. Sheet 6, for example, shows the floppy subsystem as U18 (8272A) and U14 (72X8206) feeding connector J12, with U39 (MC4044) in the data separator and pull-ups R99 10 kΩ and R87/R88 2 kΩ; the real-time clock oscillator on the same sheet is Y4, 32.768 kHz, with C83 4.7 pF, C84 10 pF, R96 22 MΩ and R97 300 kΩ, and Q4 (MMBT3904) with R70 47 kΩ on the standby side.

What it does not contain

No text layer. These are scanned drawings. `pdftotext` returns almost nothing and OCR returns garbled fragments, so read them as page images, not as text.

No parts list, no bill of materials, no board silkscreen map and no power distribution sheet. The component values that are shown are the ones drawn on the signal circuits themselves. Bulk electrolytics and the planar decoupling do not appear, so these sheets will not give you a recapping list — but they will give you the value of a specific resistor or small capacitor in a circuit you are tracing, which is more than any IBM publication does.

There is no revision history and no statement of which planar revision a Model 30 or Model 50 sheet was drawn from.

What it settles

This is the exception to the rule that no component-level data exists for IBM machines. Every IBM service manual on this wiki is module-level and names FRUs, not values. These third-party sheets do carry values on the drawings, so a value you cannot find in any IBM book may well be readable here.

Sheet 6 is also the sheet that shows the Model 30's real-time clock circuit, corroborating from a second, independent source that the 8086 Model 30 has an RTC on the planar — see IBM PS/2 Model 30.

Download it here: IBM PS2 Model 30 Schematics.pdf

Related pages

• IBM PS/2 Model 30 · IBM PS/2 Model 30 Maintenance Guide · IBM PS/2 Model 30 Troubleshooting Guide · IBM PS/2 Model 30 Capacitor Replacement Guide
• IBM PS2 Model 30 Technical Reference (January 1987) — IBM's own reference for the same machine
• IBM PS2 Model 50 Schematics · IBM PS2 Model 80 Schematics — the sibling sets