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IBM 5153 Color Display Service Manual (Sams)

From RetroTechCollection

SAMS COMPUTERFACTS, IBM Model 5153 — Howard W. Sams & Co.'s service pack for the IBM 5153 Personal Computer Color Display, the CGA monitor sold with the IBM PC and XT. 20 pages.

This is not an IBM publication, and that is the point of it: Sams reverse-engineered consumer and computer equipment and published what the manufacturers did not. For the 5153 it is the only component-level document on this wiki — IBM's own Options and Adapters section gives the specification and a logic diagram but tabulates no values.

What it contains

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  • Schematic of the complete monitor, with component designators and values drawn on it, split across the main board, the CRT socket board and the power board.
  • Waveforms and DC voltages at test points, taken with a triggered scope and an RGB pattern generator, referenced to ground.
  • Placement Chart and photographs of the main board and CRT socket board, so a designator on the schematic can be found on the physical board.
  • Preliminary Service Checks — a symptom-ordered fault list covering power supply, no raster, no video, single-colour loss and the rest.
  • Miscellaneous Adjustments — the B+, horizontal hold, colour temperature and convergence procedures.
  • Disassembly instructions, terminal guides, a troubleshooting aid and a parts list.

Sams' standard conventions apply and are printed on the schematic: "Capacitors are 50 volts or less, 5 % unless noted. Electrolytic capacitors are 50 volts or less, 20 % unless noted. Resistors are ½ W or less, 5 % unless noted."

What it does not contain

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The parts list is a semiconductor replacement list — Sams SK replacement numbers against the original transistor and IC types — not a tabulated capacitor list. Capacitor values have to be read off the schematic, using the 50 V / 20 % default convention above for anything not marked. A recapping list for the 5153 therefore exists, but only as annotations on a drawing.

It covers the 5153 only. It is not IBM documentation and carries no IBM part numbers.

What it settles

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This pack settles the 5153's own service figures, which are otherwise unpublished:

  • High voltage range: 20.5 kV to 21.5 kV at the CRT anode.
  • B+ adjustment: connect a DC meter to TP91, low side to ground, power up, and adjust B+ Adjust Control R851 for +115 V.
  • Power supply fault sequence: check AC fuse F801; if F801 is bad, check bridge rectifier diodes D801 to D804; check for 120 Vac at the output connector of the AC input board; if that is missing check coil L804; then disconnect the DC output connector from the power board and check for 115 V across it, substituting the power board if it is absent.
  • Colour adjustment controls: blue drive R506, green drive R536, blue background R517, green background R547.

Those are checkable numbers a reader can put a meter on, which is what this wiki's IBM monitor pages otherwise lack.

Download it here: IBM 5153 Color Display Service Manual (Sams).pdf

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