Dusting Under the Hood of a Konica Minolta Dimage Scan Dual IV Film Scanner

2013-04-08 3

A look inside a second-hand dedicated film scanner to locate the key parts that may need cleaning – the mirror, lens, lamp, and the sensor.

Analogue photography is great! But in this day and age, there is one vital piece of digital equipment many film photographers can’t do without – the film scanner.

Having been dissatisfied with the quality of the film scans coming out of my flatbed scanner, I decided to try a second-hand dedicated film scanner. Introduced in January 2004 by Konica Minolta Camera, the ‘Dimage Scan Dual IV’ fit my criteria for a good first-time buy that can deliver decent image quality without costing a crazily high price.

My first batch of scans yielded images with a lot of dust marks and stripes running along the length of the photos. There was nowhere near this amount of dust on my negatives, so it must have been hiding somewhere inside the scanner.

All the important scanner parts are hidden within a well-covered metal casing intended to keep dust out. Unfortunately, that also means that, over time, once the dust had gotten in, it’s not easy to get it out again without committing the crime of breaking and entering!

VERY IMPORTANT POINTS

Here comes the mandatory disclaimer: delve into the inside of any scanner at your own risk – you may ruin the machine!
Before disassembly, unplug all cables – especially the electricity supply.
Do not unscrew or otherwise mess with any screws that have been sealed with drops of red plastic glue (in the case of this particular scanner). These screws are probably securing carefully calibrated parts and tempering with them can cause optical misalignment, ruining the scanner’s function.
Perform as little cleaning as possible to sensitive surfaces (such as mirror, lens, etc). Only do what is absolutely needed; otherwise, you risk unnecessarily scratching the surfaces or introducing more dust than you were trying to remove.
As you dismantle the parts, make sure you know how to reassemble them back together again afterwards. If necessary, make notes as you go along.

Ready? Still want to go ahead?!

Removing the covers / the lamp

Always start with a clean, dust-free, stable work surface with good lighting. Unscrew the eight screws at the bottom of the scanner, and the single screw at the back. Collect all the screws in a dish so you don’t lose them; make sure you know which screws belong to which holes. Slide the top plastic cover towards the back of the scanner to remove it.

Photo 1: The scanner with the top cover removed

The lamp rests across the top of the scanner (photos 2, 3). I removed it for a quick check – it looked fine, but I gave it a quick wipe anyway before screwing it back on.

Photo 2: Arrows show the location of the lamp

Photo 3: The scanner with the lamp removed and placed at the top of the photo

The lens, mirror and sensor are at the bottom of the scanner. To get to them, we have to remove the bottom cover, which is interlocked with the front panel. Unscrew the 2 black screws on top, towards the front of the scanner (photo 4).

Photo 4: with the top cover removed, unscrew the 2 black screws at the top (shown by the arrows).

Gently release the front cover panel by a small amount only – pull off very carefully starting from its bottom edge. The panel should come off slightly, releasing the bottom cover at the same time. Pull the bottom cover away and you will find the mirror (photo 5).

Mirror

The mirror is held in place by two springy metal arms. Remove the mirror by unscrewing the metal part. Pay attention to which side of the mirror is facing outwards – this side of the mirror is marked with a red cross (beware that this mark wipes off easily, I found this out by experience!).

Removing the mirror reveals its inner surface which faces the lens. This side is silvered – clean this surface with extreme care and do not touch/put any fingerprints on it. Blow off dust particles with an air compressor or a can of compressed air.

Lens and sensor

After removing the mirror, you may be able to just see the lens hidden further inside. On the other side of the lens lies the CCD (charge-coupled device) sensor. Here’s an overview of the bottom part of the scanner…

Photo 6: An overview of the bottom of the scanner with the base cover removed. 1=mirror; 2=lens location (hidden within the black plastic housing); 3=location of the sensor indicated by the arrowhead (the sensor is shown removed, but still attached to its circuit board).

Photo 7: The lens, as viewed from the side of the sensor.

Photo 8: The CCD (charge-coupled device) sensor.

This section from the lens to the sensor is very well sealed (I’d even say entombed!) together, so it is unlikely that you will need to clean in here. In my scanner, it looked as clean as the day it came out of the factory; so I just put the parts back together again straight away to avoid introducing dust inside.

WARNING: the screws that fasten the CCD sensor to the black plastic surround shown in photo 8 are sealed with red plastic glue. DO NOT UNSCREW these screws or the sensor will become misaligned!

Results

After cleaning the mirror and some overall dusting, I reassembled the scanner. The scans made afterwards were noticeably better. One great advantage these (discontinued) dedicated film scanners have over the flatbed scanners is that they can adjust focus to the film surface. Sure enough, the scans were very sharp – the film scanner is capturing the images recorded on film more faithfully than my flatbed scanner. Here are a couple of scan results (scanned from 110 films that I put in the 35mm film holder)…