ComputingCommon

Flatbed scanner

Also called document scanner, all-in-one scan bed.

A slower, cleaner inkjet: one axis, a light bar, a rod, a belt, and a pane of glass. Often thrown out while mechanically perfect.

A donor is the dead machine. The parts below are what is still worth removing from it. “Leave it” is a part that is physically in there and should stay in there: too dangerous, too worn, or only useful as part of a repair you are not doing.

What you are looking at

A scrapped machine is a box of parts that failed at different times. The reason it was thrown out is often one bad piece. The motor, the cord, the supply, and the screws are frequently still good. This index says which is which.

Why it is in the trash while the parts are not

The interface is obsolete, or the lamp died, or it was part of an all-in-one whose printer half failed.

Before you open it

Do this while it is still unplugged, cool, and not leaking. Unplug. Old scanners have a CCFL lamp and an inverter; do not run that inverter bare.

Where the dead machine usually is

Home office — In the house
Office cleanout — Commercial
Bulk trash day — Curb

All-in-ones are the inkjet donor and this donor in one shell.

How it comes apart

Glass lifts after hidden screws. The carriage is on a rod or a rack. Keep the belt on its pulleys until you have decided you want it.

Tools: Phillips, Spudger.

Words on this page

CCFL: The thin fluorescent lamp behind older flat screens. Its driver makes a high voltage. Do not run that board loose on the bench.

What to take

The table is the short version. The notes under it describe that part inside this machine, not only the general description.

Parts in this donor
Part	Call	How many	How often	Where to look
Stepper motor	Worth pulling	1	usually	Carriage drive.
Brushed DC motor	Worth pulling	1	sometimes	Carriage, if it is not a stepper.
Timing belt	Worth pulling	1	usually	Around the carriage pulleys.
Linear shaft	Worth pulling	1–2	usually	Under the glass.
Lens and optical glass	Bonus	1	always	The glass bed.
LED array or COB	Bonus	1	sometimes	The scan bar, on LED-era units.
Switch-mode wall supply	Bonus	1	usually	Inside or a brick.

Worth pulling

Worth pullingStepper motor1 · usually
Or a DC motor. Both show up.
Carriage drive.
Take motor and belt as a set.
Good.
Worth pullingBrushed DC motor1 · sometimes
Small, with the encoder.
Carriage, if it is not a stepper.
Keep the sensor.
Good.
Worth pullingTiming belt1 · usually
Long, toothed.
Around the carriage pulleys.
Measure pitch.
Often still good, because the scanner did not run much.
Worth pullingLinear shaft1–2 · usually
Guide rod.
Under the glass.
Slide out.
Good.

Bonus

Bonus, if you are already in thereLens and optical glass1 · always
Flat glass, useful as a window or a platen.
The glass bed.
Lift straight up. It chips at the corners.
Scratched but usable.
Bonus, if you are already in thereLED array or COB1 · sometimes
A light bar at whatever voltage the board used.
The scan bar, on LED-era units.
Keep the little driver if there is one.
Good.
Bonus, if you are already in thereSwitch-mode wall supply1 · usually
Low power.
Inside or a brick.
Label it.
Good.