[sane-devel] Epson gt-8000 transparency experiment

[Bart Buitinga]

Scanner reanimation:

Pin 11 can be traced to the chassis at 0 ohms - lengthy route but 
checked (it also connects to pin 25 on the upper SCSI connector, two 
pins on the biggest square chip on the board via some mini resistors and 
equally small thingies that seem to have variable resistance but maybe 
it's just the combination. These all look fine).
Pins 10 and 2 are directly connected to the chassis
Pins 1 and 9 are together connected to the 24V parts of the main board 
(This area covers two entire edges on the upper side of the board) 
connected to the power supply connector through a 35V 100 microF 
condensator and some three pin element numbered fl4 on the board and 470 
with an underscore 0 on its dark brown square side.
0 ohms between the power supply and pin 1 (24v)

But then I thought to plug the lot back in to see if theres 24V output 
from the power supply, and with the 220 volts parts lying on a cd box, 
LIFE could be heard in the stepmotor :-) Leds also indicated the 
scanners awareness of its obvious erratic condition so I put the lot 
together again and am ready to continue. Nothing changed, really...



Martin Collins wrote:

> On Fri, 28 Nov 2003 19:39:48 +0100
> Bart Buitinga <bartbuitinga at xs4all.nl> wrote:
> 
> 
>>I'm not sure what is
>>meant with "high" when testing pins with a multimeter.
>>
> 
> High is 5V for TTL electronics, low is <1V. 24V is goodbye :-(



There we go........

connecting 5V to ground... there are some to choose from. Can't be as 
risky as the 24V though.

top row pins 1-8
bottom row pins 9-15

As said pins 2 and 10 are chassis together, 11 too, but elsewise.
3, 4, 5, 6, 7, 8, 14, 15 carry 5 volts

2-3 no life
2-4 initialising; scans as usual
2-5 same
2-6 same
2-7 error (red LED flashes)
2-8 error
2-14 scans as usual
2-15 same

11-3 no life
11-4 scans as usual
11-5 same
11-6 same
11-7 error
11-8 error
11-14 scans as usual
11-15 same

Would it be safe to connect two 5V pins together to the ground?
Would it make sense to put 5V on the 0.13V pins 12 and 13 (maybe one is 
for ADF, the other for TPU; result follows...
12-8 error
12-15 scans as usual,
13-15 same)

Maybe a resistor used to ground the errorcausers (7, 8), instead of the 
bent paperclip so far used, could make a difference?



I've come back on my plan to intercept the tube feeding cables: The 
screws in the lamp/sensor unit have been tightened too fanatically and 
the part seems to fragile to risk heavier tools or chemicals. Or maybe 
I'll just drill them out if I can immobilise the thing, but that's for 
later.

But it feels good to be back in the modern colorful world. Please klick 
on any picture at http://www.xs4all.nl/~labrat to see what that means.

Bart Buitinga


> 
> 
>>So I tried connecting 10-12, 10-13, 2-12, 2-13,
>>
> 
> What was probably needed was to connect the right 5V line to a 0V
> line, one or more of which would be ground.
> 
> 
>>No more signs of life at all.
>>
> 
> Ouch, sorry to hear that...
> 
> 
>>(Or has anyone around got the specific experience I need now???)
>>
> 
> You could try looking at the circuit board. If there are no obviously
> burnt out components follow back from pin 1 (or pin 11 if it is not
> connected to ground) and replace each component in turn until it works
> again. If there is an obviously burnt out component hope it is still
> identifiable and is not an eeprom or something irreplaceable.
> Good luck.
> 
> Martin
> 
>