Pentax EPK-i7010: xenon lamp does not ignite, unit falls back to LED light source
What happened
The main xenon light source would not start — no ignition sound or strike; the unit automatically switched to the backup LED source.
What was checked
- The xenon lamp was swapped into a working identical unit and lit there, so the lamp itself was ruled out.
- Voltage was measured at the power supply output terminals during the ignition attempt; reported in the case, around 200 V was expected at ignition and 13.8 V after the lamp struck.
Cause
The engineers found a resistor with an integral thermal fuse inside the power supply open-circuit, which interrupted the ignition circuit so the xenon lamp could not strike.
What was done
The engineers replaced the failed resistor with thermal fuse in the power supply using a part of the same type and rating, and ignition returned to normal. As a reference reported in the case: about 200 V at the output terminals during ignition, 13.8 V after the lamp is running.
Safety
The xenon ignition circuit works at high voltage and the power supply holds stored charge — unplug the unit and let the capacitors discharge before opening it, and run electrical safety checks (protective earth and leakage) before returning the unit to use.
Lesson: When the xenon source silently falls back to the LED backup, verify the lamp by substitution first, then measure the ignition voltage at the power supply output to separate a lamp fault from a power supply fault.
Covered in the course: Endoscopy Equipment 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.