Agfa Drystar 5300: printer reboots at power-up, PSU LEDs blink
What happened
On power-up, the indicator LEDs on the power supply blink and the printer immediately drops into a reboot loop. No error codes were reported in the case.
What was checked
- After opening the power supply, the engineers measured the reported 24 V rail and found no output voltage.
- They inspected the 24 V power path for burn marks and heat discolouration.
- They tested the power switching transistors and the resistors in their supply/control circuits.
- They checked and re-flowed the ferrite coils and the high-wattage resistors on the power board.
- They confirmed the fault was in the supply itself, not in the printer.
Cause
The engineers found one failed power switching transistor, with internal burn damage on the 24 V power circuits and no 24 V output — the printer was losing its main low-voltage feed and restarting continuously. This is a single reported case, so treat the cause as probable, not a rule.
The cause is probable and was not fully confirmed.
What was done
Component-level repair of the power supply: the burnt power transistor was replaced, the damaged 24 V power paths were restored, and the coils, high-wattage resistors and solder joints on the power board were inspected and re-soldered. The outcome is described as probable in the case, so verify full operation before returning the printer to service.
Safety
Unplug the printer, allow the filter capacitors in the power supply to discharge and verify absence of voltage on the power stage before any work; after any supply repair, complete the electrical safety checks (protective earth continuity and leakage current) before the unit goes back into use.
Lesson: When a printer reboots immediately at power-up, check the supply's main output rails (here the reported 24 V) before digging into the printer itself — blinking supply indicators usually point at the PSU.
Covered in the course: Medical Imagers and Film Printers — 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.