IBM 5151 - Known Problems/Issues
SYMPTOM: Brightness and contrast knobs do not turn easily
A known behaviour. IBM may have intended this.
SYMPTOM: No video, but a stable raster shows if brightness turned up
If the brightness control is turned fully clockwise, a stable raster shows (example), but there is no video.
For the IBM 5151 (not other monitors), the stable raster informs us that the 5151 is receiving correct horizontal and vertical sync signals from the MDA video card.
Known cause: Contrast control set too low.
Known cause: IC201 (an SN7406A) in the 5151 is faulty. This has been reported by at least two people.
Possible cause: Faulty MDA video card (generating sync signals, but not a video signal). Try a known-working MDA card.
Possible cause: Faulty cable (wire for video is open-circuit, either permanently, or intermittent).
Possible cause: Pin 7 (video) within the 5151's DE-9 plug has poor/loose connection to the video card's DE-9 connector.
SYMPTOM: No display (not even a raster)
Even if the brightness control is turned fully clockwise, no raster (example) appears.
Possibilities follow:
• Faulty 5151.
To get any display at all (including simply a raster), the 5151 requires that a horizontal sync signal is coming into the 5151 from an operating MDA video card.
Therefore, the following are possible causes as well:
• Not connected to an operating MDA video card.
• Poor connection to operating MDA video card. Includes oxide build-up on connector pins, etc.
• Faulty MDA video card.
• MDA video card has not been initialised. (Example cause: 5150/5160 motherboard switch settings set to EGA, instead of MDA.)
SYMPTOM: Bright spot/line when turning off
An example photo of the line is at here.
This is known behaviour.
See the discussion at here.
Damage to 5151 from improper horizontal sync signal
Due to the design of the 5151, an improper horizontal sync signal (i.e. not conforming to MDA standard) can damage the 5151.
Even software can cause that situation. Example at here.
Pins 3, 4, and 5 are missing from the 9-pin D connector
That is normal. Pins 3, 4, and 5 are not used in the MDA standard (see here).