[sane-devel] Epson gt-8000 transparency experiment

Bart Buitinga bartbuitinga@xs4all.nl
Fri, 28 Nov 2003 19:39:48 +0100

Karl Heinz Kremer wrote:

> A "real" TPU is just a lamp behind some ground glass (or translucent 
> plastic), so
> there is not "projection" involved: The sensor scans the illuminat4ed 
> negative or slide
> directly.
> Have you checked out the link to the message from the guy who is using a
> lightbox on his Perfection 1200? He had some instructions about how to
> disable the 1200 TPU. The GT-8000 should be similar.

Of course that's what I forgot, and it looks promising. Even though the 
connectors are different (The gt-8000 looks like a game port, while a 
mini DIN connector is described but I'm not sure what is meant with 
"high" when testing pins with a multimeter.

Described pin readouts:
By Byron, just another bb to keep things clear...
Option Connector on Scanner = 8 pin mini-DIN receptacle

My pin nomenclature is:
    Top Row  (Left to Right)     = One,  Two, Three
    Middle Row (Left to Right)  = Four, Five, Six
    Bottom Row (Left to Right) = Seven Eight

Input and Output is referenced to the Scanner (ie Input means input to 
the Scanner).

Pin One = Output, function unknown.
Pin Two = Output, function unknown.
Pin Three = Input,  Default High.  Low means TPU present, sampled at Power
Pin Four = Ground
Pin Five = Output, function unknown
Pin Six = P/S Output, +24v when TPU (either pos or neg) is selected.  0v
Pin Seven = Ground
Pin Eight = P/S Output, +5v

Fortunately, this BB also has a multimeter and assuming 200v dc would be 
adequate for starters for the 15 pin "gameport" results are: (top row 
left to right, bottom the same)

1. +23.6v
2. 0,0
3. +5,0
4. +5,0
5. +5,0
6. +5,0
7. +5,0
8. +5,0
9. +23,6
10. 0,0
11. 0,0
12. +0,1
13. +0,1
14. +5,0
15. +5,0

So I tried connecting 10-12, 10-13, 2-12, 2-13, switching the scanner 
off and on each time and reloading twain32, then was called for dinner 
and then blew it by accident: 2-10, 1-11 :-( Initially I was even glad 
to see no light from the initialisation until I noticed the LEDS where 
out too...
No more signs of life at all.

Now I opened the power supply and find one fuse, but not blown... I 
guess I just no longer own a working GT-8000 any more... Not mad, just 
sad... I'll be back... maybe, or maybe find me a scanner with a prebuilt 
TPU some day

(Or has anyone around got the specific experience I need now???)

BB for now retracts into the darkroom
Who needs computers anyway?

But it was fun while it lasted,

Bart Buitinga

> ... and I can assure you there is no mechanism to turn the lamp off 
> without a
> TPU (or a fake TPU) connected to the scanner.
> Karl Heinz
> On Friday, November 28, 2003, at 08:20 AM, Bart Buitinga wrote:
>> Hello again,
>> It's going to be some retro demonstration if this goes to work. Thanks
>> for all your replies.
>> After some fiddling with the configuration files I found the number that
>> defines "Blindfarbe" (shines just one of the three monochrome tubes in
>> the gt-8000's sensor) for BW modes can be set 0 for none or 1, 2, 3 for
>> R, G, an B. Unfortunately -1 an 4 both default to none. If there's no
>> known way to override the hardware detection I think I'll just add a
>> switch in the internal power cable to the tubes to get them off, also
>> because the autodetection of accessories, as it differs between the
>> document feeder and the TPU is beyond just shortcircuiting and of course
>> I wouldn't want to risk this splendid device that the previous owner
>> must have thrown away after obtaining a new pc with ECP or similar.
>> I've been trying some combinations without a projection screen, but I
>> think the sensor would demand a strictly parallel bundle for that to
>> work. (That is of course possible, but would take a lens the size of the
>> print.)
>> Just hoovering the enlarger over the scanner only results in a light
>> spot at the position of the enlargers lens
>> Considering the amount of light: I think a projector would be overdone
>> if theres no need to overpower the scanner tube or false light. These
>> old enlargers have relatively strong lamps because in the pre-multigrade
>> days high grade photo paper was not too sensitive.
>> But if the Opemus lets down, I also have a Krokus 3 with a condensor
>> extension that throws all the 100 watt light through a 35 mm window
>> instead of its usual 6x9 cm, about 3 times more powerful
>> (And also: It would then help to scan on less than a4 format... Also it
>> has the same lens entrance as my Praktica, so it may be easy to use it
>> with a large diameter telelens to get an up to 60 mm wide parallel
>> bundle... Well allright, I know what I'll do this afternoon)
>> But if someone around actually has a TPU, I would be very interested
>> what kind of projection (screen or parallel) it uses.
>> Bart Buitinga
>> Martin Collins wrote:
>> > On Thu, 27 Nov 2003 21:02:43 +0100
>> > Bart Buitinga <bartbuitinga@xs4all.nl> wrote:
>> >
>> >
>> >>It occurred to me that if it is possible to project a negative on
>> >>the scanners glass pane using a slide accessory, it might also work
>> >>to use a photo magnifier (I mean the thing used to print in a (B&W)
>> >>darkroom, an Opemus 11 to be precise)
>> >>
>> >
>> > An enlarger. You might also use a projector.
>> >
>> >
>> >>with some kind of half transparent projection surface,
>> >>
>> >
>> > It might work better without a screen, just project the image straight
>> > into the sensor.
>> >
>> >
>> >>just if I would succeed in scanning with the lights off.
>> >>
>> >
>> > Right, you would need to turn the lamp off. Although, if you didn't
>> > use a screen the lamps may not matter.
>> >
>> >
>> >>I guess that normally the scanner would notice a device connected to
>> >>the 15 pin entrance on the rear, and maybe it would just be a matter
>> >>of shortcircuiting some of its contacts, but maybe there is a trick
>> >>to do it with one of the ini's that twain32 (win95) uses. (In the
>> >>latter case I hope there's a similar linux option or continue my
>> >>quest elsewhere)
>> >>
>> >
>> > I don't know if the sane epson backend can directly control the lamp,
>> > I know the mustek one cannot. So you need to fake the scanner into
>> > thinking it has a transparency adapter connected. That 15 pin
>> > connector probably has 24V on some of its pins so don't go shorting
>> > any of them unless you know what they connect to. If you don't have a
>> > TPA so can't sniff its protocol you could open up your scanner and
>> > disconnect the lamps.
>> >
>> > I would try it with the lamps on and no screen first, see what you
>> > get. Please tell us the results of your experiments.
>> >
>> > Martin
>> >
>> >
>> -- 
>> sane-devel mailing list: sane-devel@lists.alioth.debian.org
>> http://lists.alioth.debian.org/mailman/listinfo/sane-devel
>> Unsubscribe: Send mail with subject "unsubscribe your_password"
>>             to sane-devel-request@lists.alioth.debian.org