The platform: film path, laser exposure, drum processor, boards and software

Name every assembly of the DRYPRO SIGMA in the order the film meets it, say which board controls it and which sensor watches it, and know where configuration, logs and software live.

What sits on the bench

The DRYPRO SIGMA is a desktop dry laser imager: one supply position for a light-tight film cartridge, a red-laser exposure unit, a heated drum processor, a built-in densitometer and an exit tray on top. The manufacturer's public page describes it as a silver-halide dry laser imager that prints four film sizes from one supply and works as a DICOM printer without a separate print server. That last point matters on site: unlike some older DRYPRO models that, by field reports on the DRYPRO 832, needed an external print server PC, the SIGMA carries its own computer inside, and the network cable from the modalities goes straight into its back panel.

The service manual for this model, document 9G9002, is organised by task: installation, adjustments and replacements, preventive maintenance, diagnostics, parts list and additional procedures. This course reorders that material around the film path and the fault in front of you. Keep the manual open for exact steps, screws and values; here you learn what each block does, how it fails and what proves it works.

Two names will follow you through the whole course. The DRE board is the embedded PC motherboard with its flash drive. It runs the operating system, the DICOM print server, image rendering, the logs and the web-based service tool. The MCS board, the machine control system, runs the mechanics: motors, sensors, interlocks, the heater, the laser module interface and the local display. Almost every fault you meet is either on the DRE side (software, network, image data) or on the MCS side (film handling, temperature, optics), and the condition code tells you which before you take a cover off.

Supply and pick-up: cartridge, rollback, suction and feed nip

Film arrives in a sealed cartridge with an RF tag. When the cartridge is pushed into the film supply and the supply is closed, the imager reads the tag: film type, size, sheet count and whether that cartridge has been calibrated. After each sheet it writes the new count back. A tag that cannot be read or written, or a type or size the imager is not configured for, stops the supply before any mechanics move.

Because the cartridge is light-tight, the imager must open it. A rollback mechanism driven by its own motor rolls the cartridge cover back and later closes it again; a rollback home sensor tells the MCS where it is. This is why the operator presses the Pause symbol before removing film: the imager finishes the sheets in progress, closes the cartridge, and only then is it safe to open the supply without fogging the film. A cartridge pulled out half open is a classic source of fogged sheets and of rollback errors.

Pick-up is by vacuum. The pickup assembly lowers an arm with silicone suction cups onto the top sheet; a small vacuum pump behind the back cover provides suction through tubing; a film contact sensor confirms the arm has reached the film and a pickup home sensor confirms the arm is back up. The lifted sheet is handed to the feed roller nip, which a separate motor opens and closes and a feed roller sensor monitors. If the sheet does not arrive at the start-of-page sensor, the imager retries; the manual says it gives up and declares a pickup failure on the third successive attempt.

The manual numbers the sensors along the path: S1 tells the MCS a cartridge is present, S2 that the rollback is at its home position, S3 that the pickup arm is up, S4 that the arm touches film, S5 where the feed roller is, S6 is the start-of-page sensor in the exposure transport and S7 watches film at the densitometer. Learn this list; the jam codes in lesson 4 are written in terms of these sensors.

Exposure: imaging assembly, polygon and the start-of-page sensor

The imaging assembly combines two units you can separate on the bench: the optics module and the exposure transport. The exposure transport carries the sheet past the scan line on an imaging roller driven by its own motor and belt. The start-of-page sensor S6 sits here and is used several times per sheet: it sees the leading edge, it watches the de-skew move, in which the film is driven back and forward again to square it up, and it sees the trailing edge as the sheet goes to a holding area the manual calls the accumulator and later on to the processor.

The optics module holds the laser diode, its power control and a rotating polygon mirror that sweeps the beam across the film while the transport moves the film past the line. The optics microcontroller checks polygon speed and runs an optics calibration that measures the laser power monitor offset, the dynamic range and the maximum power. When those values approach or exceed their limits the imager writes notifications and then fatal codes. A beam power that slowly drifts toward its limit over months is one of the typical end-of-life patterns of laser imagers, and on this platform the log tells you before the film does.

Image data travel from the DRE to the optics module over a dedicated USB cable to what the manual calls the DPB. If the right number of pixels does not arrive in the allotted time, the imager reprints and logs a transfer error; three in a row become a fatal error. Remember that link: a cable at the back of the machine can produce a code that looks like an optics failure.

Two timing adjustments live in the optics configuration: the index delay, which centres the image left to right, and the page start delay, which places the image relative to the leading edge. You will meet them after an imaging assembly change in lesson 5.

Development and exit: drum, cover rollers, cooling and densitometer

After exposure the latent image is developed by heat. The processor is a rotating drum with a silicone surface and an internal heater; pressure rollers in the processor cover hold the film against it. Drum temperature is measured by an RTD inside the drum, and both the heater power and the RTD signal pass through a slip ring because the drum turns. The drum is driven by a stepper motor and a toothed belt. The manual sets the drum temperature window at 123.5 to 124.5 °C, measured with a bar-type probe, and density depends directly on that number.

Leaving the drum, the film passes a film diverter and a felt pad, then a cooling plate under a heat shield, so that it is stable before it is measured and handed out. The densitometer sits in the cooling assembly with its own film sensor S7. It reads the 21-step calibration wedge that the imager prints on each new cartridge and feeds the automatic image quality control, which the manual calls AIQC. The film then exits to the tray on top.

Thermal development releases vapours. Air is pulled through the processor and out through a deodorant filter under the film supply, moved by two fans, with ducts and an exhaust plenum and exhaust holes in the left cover. Residue condenses on cooler parts: the heat shield, the cooling plate, the densitometer guide, the cover rollers and the drum itself. This is the reason the preventive maintenance in lesson 3 is mostly about heat, residue and air flow.

Power, interlocks, panel and the software layer

Mains enters at the back through an inlet and a rocker power switch with circuit breakers; the label above the inlet states the voltage range the unit is set for, and the manual tells you not to continue an installation if it does not match the site. A single switching power supply feeds the low-voltage electronics, fans and motors; the parts list describes it as 24 V and 65 W. The drum heater is switched by a solid-state relay together with a mechanical power relay, and the drum carries a thermal circuit breaker as a separate protection.

Three interlock switches watch the top cover, the left cover and the film supply. An open interlock stops printing and removes the laser from service; opening a cover during the power-on self-test produces its own fatal code. Treat the interlocks as part of laser safety and never defeat them. The MCS board has status LEDs that show heater activity, a healthy CPU and whether all interlocks are closed; they are useful to read with the right cover off and the power on, under the precautions of lesson 5.

The local panel is a small display with symbols and a three-digit code field. It talks to the MCS over a serial link. Behind it, the DRE runs the web-based service tool that you reach from a laptop on the service port, using the manufacturer's secure tunnel client and portal software with authorised credentials. Through it you see the imager monitor and counters, configuration, test prints, the error history and eight logs, and you make and restore configuration backups. Access, credentials and elevated rights belong to the manufacturer's authorised service organisation; this course does not cover how to obtain them.

Know where data live. Configuration can be backed up to the DRE flash drive and downloaded to a laptop as a file. The DRE also holds print jobs and logs; both can contain patient names and identifiers, which is why saved logs and spare flash drives are handled as patient data.

On-site checklist

• Model, serial number and software version recorded from the service tool
• Film type and size in the cartridge noted; cartridge expiry checked
• Pause used before the supply is opened
• Sensors S1 to S7 and interlocks I1 to I3 located on the machine
• Configuration backup present on the laptop before any change
• Saved logs and backups stored as patient data

Check yourself