Baccara 90/20: cassettes not recognised with the table horizontal
What happened
As reported in the case, cassettes inserted into the bucky were not recognised when the table was horizontal — the size read out as 00x00. With the table vertical or only slightly tilted, size detection worked normally.
What was checked
- The engineers confirmed the pattern: detection failed only in the horizontal position and worked when the table was vertical or tilted.
- Mechanics were checked and found normal: the cassette sat flat and centred in the receiver.
- A search of the schematic for size-detection potentiometers came up empty — a wrong lead, since in this design the size is detected optically, not potentiometrically.
Cause
The cassette size is sensed by a small flag under the movable deck that passes through the slot of an optotransistor. In this case the flag was bent inward, so in the horizontal position it missed the sensor and the system read no cassette at all (00x00); in vertical or tilted positions the geometry evidently still brought the flag into the sensor's line of sight.
What was done
After going back to the detection principle and locating the flag and optotransistor under the deck, the engineers straightened the bent flag so it passed the sensor cleanly in all table positions; size detection was restored and the case was reported as solved. No parts were replaced.
Safety
Before reaching under the movable deck or into the stand mechanism, isolate the equipment from the mains and secure the table and deck against unintended movement or tilt — the deck and its counterbalance can shift with enough force to crush hands.
Lesson: Trace how a parameter is actually sensed before chasing electronics or calibration — a bent mechanical flag at an optocoupler can look like a detection fault that depends on the table position.
Covered in the course: X-ray Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.