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MMD > Archives > January 1997 > 1997.01.08 > 07Prev  Next

HP Scan Jet for Optical Roll Scanner
By Spencer Chase

I just found some junk that I thought might be useful to make a low cost precision roll scanner. I debated writing to the MMD thinking that by now everyone has become bored with my reader/scanners babble. Then I discovered that others may be using the same approach, so here goes.

I disassembled an HP Scanjet (original B&W) scanner and found typical Hewlett-Packard quality inside. There is a real nice lens that focuses on a line CCD and all the electronics to drive it. The lens focuses a line from the source through a folded path of front-surface mirrors. Since the roll would be the thing to move in a roll scanner, it should be easy to change the focus, eliminate the mirrors and cover a typical roll width with sufficient precision.

The problem lies in reverse engineering the thing. I know that CCDs are not easy to drive, but all the electronics should be there. The driver board has a power connector, and an input and output plug each to a hex inverter. There are a few other basic chips and a part I can not identify (Hitachi's HA19202, which wasn't found on a search of their Web Site.) There are no other connections to the board. By finding the function of these input and output connections it should be easy? to control this thing.

I would like to avoid using the motherboard and trying to reprogram the prom etc. I would hope to use an input board with timing functions. I have tried to get information from HP via their Web Page, but have not succeeded. Does anyone have information on these things, or know how to get it? A schematic and a logic and timing diagram would be nice, but a real thick book like they used to make would be fun.

If this approach works out, it might be a good way to get a bunch of scanners going fast and cheap. I really want to be involved in preserving this musical heritage, before it is too late, but I have a limited amount of time to dedicate to the task. I have noticed that my musical taste is continually changing and that I now appreciate music I would have passed on before. This is part of the reason that I would like to be involved in archiving all this stuff and especially interested in making it a collective task. You never know what you may want in the future and it may be gone by then.

Spencer Chase

[ Which model Scan Jet is it, Spencer, and how does it come apart?
[ We couldn't get inside a Scan Jet when we tried! -- Robbie

(Message sent Wed 8 Jan 1997, 21:57:17 GMT, from time zone GMT-0800.)

Key Words in Subject:  HP, Jet, Optical, Roll, Scan, Scanner

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