IBM 5151 Monochrome Display

The IBM 5151 is a 12" transistor–transistor logic (TTL) monochrome monitor, shipped with the original IBM Personal Computer for use with the IBM Monochrome Display Adapter. A few other cards were designed to work with it, such as the Hercules Graphics Card.

The monitor has an 11.5-inch wide CRT (measured diagonally) with 90 degree deflection, etched to reduce glare, with a resolution of 350 horizontal lines and a 50 Hz refresh rate. It uses TTL digital inputs through a 9-pin D-shell connector, being able to display at least three brightness levels, according to the different pin 6 and 7 signals. It is also plugged into the female AC port on the IBM PC power supply, and thus does not have a power switch of its own.

The IBM 5151 uses the P39 phosphor type, producing a bright green monochrome image intended for displaying high-resolution text. This phosphor has high persistence, which decreases display flicker but causes smearing when the image changes.

Documentation

9-pin D connector pin assignment, and sync pulses

See here.

BIOS Video Modes

See here.

Known Problems/Issues

https://www.minuszerodegrees.net/5151/problems/5151_known_problems_issues.htm

How to open?

You can open the monitor by unscrewing the two screws facing forwards at the base of the monitor, and the two hidden screws under the plastic plugs on top of the monitor. I used a small flat-headed screwdriver for removing the plastic plugs, which shouldn't be too hard; they're not that fragile.

Note 1: With its cover off, the 5151 is physically unstable (except when face-down).

Note 2: The case comes apart after removal of two screws topside, and six screws underside. On the underside, do not remove the two screws that are covered, because removal of those together with the remainder will result in the power transformer and its mounting plate coming loose within the case and causing damage.

Video on YouTube: https://www.youtube.com/watch?v=twgD-u7OPVw