IBM 5151 - Known Problems/Issues
SYMPTOM: No display
• 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: 51xx motherboard switch settings set to EGA, instead of MDA.)
SYMPTOM: Bright spot/line when turning off
A 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.