Summary: Voluntary recall notice for Mustek A3USB 1200 Pro Scanner.
I am writing in regards to what may be a faulty line of Mustek A3USB 1200 Pro scanners. I received this unit for review in early May 2011 and have determined that the focal distance of the employed photo detector to be too short, or excessively divergent. This results in an overly narrow distance for which images can be acquired without distortion or blurring. It is my opinion that this entire line of scanners be recalled; a software/firmware fix may not be sufficient. I believe the fault is the result of inappropriate component selection, particularly the photo emitter/detector.
I have conducted the following tests:
CPU scan test
The first image scanned was that of a typical socket 3, 486 CPU, top and bottom. The top face of the CPU scanned correctly since the surface is pressed completely flat against the glass, however the bottom of the CPU is blurred beyond recognition. The bottom surface of the CPU is raised approximately 6 mm above the glass (the height of the CPU pins). I have done the same CPU scan test with an ancient UMAX Astra 600S SCSI scanner (which is still working and in use), whereby the top and bottom were both perfectly in focus. The UMAX Astra 600S is a similarly priced entry-level scanner in its day, $179 USD in 1997.
The difference with the UMAX technology is that the focal distance has a wider range. It is like taking a photograph with a camera at 30-50 feet, everything will be in-focus without adjustment of the lens.
Maybe you don't care about scanning items 6 mm from the glass surface, so how about a typical text book or a map? See below.
Textbook scan test
I did another scan of an open-faced textbook, 2 pages in one scan. The textbook was pushed as flat as possible on the scanner's glass surface. The entire centre region where the book is bound cannot be read because of the focal distance problem. It is not like with a photocopier where you can sorta make out the text near the centre binding; this text is completely unrecognisable. Scanning a book is typical scanning scenario that maybe 50% of customers will likely be interested in.
Don't want to scan textbooks? Ok, how about a map?
Map scan test
The next scan test was that of a folded map which was pressed down onto the glass with the weight of the scanner lid. The scanned image is scattered with blurred and clear sections. The blurred sections are from areas of the scan where the map was just barely raised above the glass surface, maybe less than 1 mm. The text is not recognisable, again due to the focal issue of the employed optics. Even when pressing the map down with a heavy book, not all areas of the scan were focused (but more so).
So what can you scan with the Mustek A3USB 600/1200 Pro scanner? No much. You are limited to a flat piece of paper which is pressed down firmly with a large flat object. If that is all you want to scan, you are better off saving space and getting a paper fed scanner.
In conclusion, it would seem that the Mustek scanner has no focal adjustment, or that the fixed focal length is too narrow. This will become a major issue, not just now, but for the longevity of the scanner as slight movements in the components, i.e. via gravity or warping, will further alter this very sensitive focal length. If the problem is not firmware/software correctable, I would suggest that Mustek issue a hardware fix-it pack for which the customer could install a new emitter/detector, otherwise a full recall may be in order.
This problem report has been sent to the project manager at Mustek in charge of this scanner line, however no comment has been received to date.
