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Bad Data

Sharp Retro Computer

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Sharp MZ Bad Data Error — Tape Read Failure

What Does This Error Mean?

Sharp MZ shows 'Bad data' (or 'BAD DATA') when the cassette load reaches a CRC check that fails.
Tape audio is degraded, the head needs cleaning, or azimuth is misaligned.
Clean the tape head with isopropyl alcohol, adjust the azimuth screw a fraction at a time, and try again.
If multiple tapes fail, the head needs full cleaning or the tape is damaged.

Affected Models

  • Sharp MZ-700
  • Sharp MZ-80A
  • Sharp MZ-80B
  • Sharp MZ-80K
  • Sharp MZ-1500
  • Sharp MZ-2500

Common Causes

  • Dirty tape head
  • Azimuth misalignment between recording and playback
  • Damaged or stretched cassette tape
  • Volume level wrong (too low or too high)
  • Old cassette has lost magnetic signal

How to Fix It

  1. Clean the tape head.

    Use isopropyl alcohol (90%+) on a cotton bud.
    Open the cassette door and gently rub the head and pinch roller.
    Let dry 30 seconds before testing.
    Brown gunk on the swab means the head was filthy.

  2. Adjust playback volume.

    Set volume to mid-range first.
    Too low: weak signal, CRC fails.
    Too high: clipping, CRC fails.
    Some MZ machines like a specific level — try 5/10 or 6/10 first.

  3. Check azimuth alignment.

    Tiny screw next to the tape head adjusts azimuth (head angle).
    Play a known-good tape and turn the screw 1/16 turn at a time.
    If LOAD progresses further with a turn, you're going the right way.
    Reverse direction if it gets worse.

  4. Try a different cassette.

    If only one tape fails 'bad data', it's the tape — magnetic decay or physical damage.
    If every tape fails, the deck or head is the problem.

  5. Convert to WAV and load via line-in.

    If you have access to the tape image as WAV (many MZ tapes are archived online), play it from a phone or PC line-out into the tape input.
    This bypasses head and azimuth issues entirely.
    Check that polarity matches your machine.

Frequently Asked Questions

Why does the same tape sometimes load and sometimes fail?

Marginal signal levels, a slightly dirty head, or temperature changes can flip the result.
Cleaning the head and stabilising the audio level fixes most random 'bad data' failures.
If the tape is over 40 years old, expect degradation regardless.