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24 Pixel Line- Again!


Tony.T

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My 1550 has just started ramdomly printing the 24 pixel line. Some days it's ok, others, like today it comes and goes at random :angry: 

 

Been looking back through threads, I have seen several mentions about changing a resistor from 1.2 kohms to 800 ohms. A few people reported that it seems to work. Does it? Even if it's only for a few months that will be enough.

 

If it does work where can I find it?

 

If not, and I need to get the lcd changes, who are the best  people to use in the UK? Any independents?

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Yes it works and you can find it in some electronic shop, I think I used 820 ohms as that shop did not have 800 ohms resistor.

 

I installed it on several machine (include one in our office lab) and it works without problem Off course you have to set up the flicker and probably do a new PRNU test  ;)

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Tony, unfortunatelly 24 pixel line is the biggest nightmare in DKS machines. Adding this resistor will eliminate

temporaly the problem. How long? :It depends on how much prints you do, perhaps 1 month, 2 months, 3 weeks...

difficult to say.

Possibly you'll have to adjust flicker (not 100% necessary) see how prints are if you see some screening in

a long uniform area like sky. Adjust flicker is very easy to do (not so easy to explain).

PRNU? I only did PRNU when I changed LCD, not when I had to add resistors.

About LCD you'll have to reppair it or buy a new one. I'm very happy with the results of Alertoff. I send him

to repair 6 months ago and still working for a very reasonable price and time.

 

Greetings.

Studio01

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- oh, and where in the machine is this resistor to be found exactly- I'd hate to change the wrong one  :rolleyes:

 

The resistor is positioned on the bottom PCB which rotates together with the LCD, I can add later the necessary technical info document, but I would not advise to do it yourself   :o

 

Because to add that resistor or change the existing one for that one it is necessary to completely pull down the LCD subassembly and that is work for a trained technician. Also after that complete centering procedure have to be done. PRNU is sometimes necessary to do but more often it is not  ;)

Edited by pskaro
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This is the technical info regarding the resistor and solving the 24 line pixel problem. This procedure is related to adding original 1.3K ohms resistor, but it is same procedure also for adding 800-820 ohms resistor.

 

Off course the existing one have to be removed or you can add it in right to existing one, but then this jumper pins have to be changed for 3 pins version with the ground in the middle and in that way all combinations are possible, as I done on our office machine.

 

Without resistor, with 1.3 k ohms resistor and with 820 ohms resistor, depending off the jumper combination, and in that way even if the NEW LCD is fitted at some point, and if the 24 line pixel appears it would be not necessary to pull down the LCD S/A to change the resistor ;)

71 V02 ed 01_24 pixels lines & DRIVER EPSON PCB.pdf

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Few remarks. 

1. ABLSOLUTELY NO NEED to dismantle full LCD subassembly - it lasts to remove Epson Driver PCB - it is MUCH EASIER to perform altough it is little bit tricky - but not complicated. Few screws and nuts to remove + flexible tape.

2. Before you change from 1.3k to 820 - consider intermediate values. I have signal that change from 1.3 to 1.2k made the 24p lines dissapear. In other case I have set up the machine with 910 Ohm resistor.

3. 820 ohm is an absolute  limit. You can damage your epson driver card attaching lower values. I would even suggest 880 as lowest value possible. 

4. Calibration - After resistor apply, 1st thing is to set flicker. Be sure that polariser and gain could require adjustment (not necessary if resistor change was minor) - since all colors are shifting to blue due to the LCD voltage increase. 

Probably you will not be able to reach factory parameters on LUT... this needs to be performed as well .

PRNU is mandatory - I suggests needs to start from scratch.

Edited by relaxia
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Had a look at the Circuit board- looks straightforward to remove, but does the ribbon cable at the top of the board unplug from the board?

 

Had a look at PRNU, the instructions look quite straightforward, so I'm happy to give that a go. I found a file in the 'D' drive titled SCAN and the date, I presume this was when an engineer did a PRNU test. Do I delete that and add my own  bitmap?

 

Finally, I can't find the flicker test- can someone explain how it done?

 

I've got a resistor coming so I'm going to have a go at this modification. I've decided I've got nothing to lose- if it doesn't work I'll just have to get a tech to fit a new LCD. Any idea what this might cost in the UK?

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Guest quick_film

Hi from Greece. With the help of the friends in this forum , i repaired successfully my 24 pixel problem. A friend specialized in electronics soldered the resistor without dismantling anything . Then it worked ,but i had some very thin lines especially in areas with big parts of some color... So i went in the " S.U" from the main screen of the program using the "DKS 1500" password and from the "Settings ->  CAMERA "  tab  i lowered the Flicker valeu . So now it is O.K. I had also the help of the Service manual for DKS 1500 (page 303) P.S. I give you the Service Manual zip , in case you need it... https://rapidshare.com/files/3722997927/DKS%2015xx%20Service%20Manual.zip;BB304E3D7DABE3BCF2C9A215FE62D265;

Edited by quick_film
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Had a look at the Circuit board- looks straightforward to remove, but does the ribbon cable at the top of the board unplug from the board?

 

Had a look at PRNU, the instructions look quite straightforward, so I'm happy to give that a go. I found a file in the 'D' drive titled SCAN and the date, I presume this was when an engineer did a PRNU test. Do I delete that and add my own  bitmap?

 

Finally, I can't find the flicker test- can someone explain how it done?

 

I've got a resistor coming so I'm going to have a go at this modification. I've decided I've got nothing to lose- if it doesn't work I'll just have to get a tech to fit a new LCD. Any idea what this might cost in the UK?

1. ribbon cable - YES. you must unplug it. on the edges of the connector you have small locking devices. U need to pull it uot then flat ribbon will be free and goes freely. 

 

2. PRNU - DO NOT DELETE ANYTHING before you run first trial pictures.

No need to delete Scan.BMP file - this is only temporary file. 

 

FIRST OF ALL - you need to set the flicker. Quick_film gave you a hint and manual.

(BTW I agree it is possible to add resistor without board removal but it is more complicated than third level of yoga. Need to remove top housings to have possible access) 

when flicker set - run your quality pictures and PRNu picture. If colors are good and you see only minor thin lines - Run PRNU Procedure - one or 2 steps with pixelsize=7 or first at 7 and second at 9.

If colors went to hell and you have lot of blue on the pictures - whole optic line to be set. Polariser, gain in minor level, LUT...

then you need to find PRNU files in right directory (3 files PRNUR, PRNUG, PRNUB - all bitmaps) change their names ( *.bak for example) restart machine and do PRNU from scratch. 

READ CAREFULLY whole procedure - looks simple but takes lot of time especially when U want to do it right and with all the steps. can take whole day... need to have perfect cleanliness of the scanner glass - form both sides - this is crucial for the work efficiency. 

 

3. fitting the LCD... rather not complicated but all further work takes time and UK labour costs are... high. let's say.

share the quote when you get it - I will check If  I would be able to score on UK business trip :P  :lol:

 

Generally if you have problem with sevicing the machine I would suggests to ask some of your business friend who know better topics - to get a strong support and hand within reasonable time.

Overcalculations about own possibilities and limitations can be much more costly. 

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Thanks for all your help. I have everything I need now to do this.

 

At the moment it seems to be working OK, but I have no doubt this is temporary!

 

If I understand you correctly Relaxia- perhaps you could give me a quote for a trip to the UK? Best to use my e-mail address-

 

qualityexposed@btinternet.com

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relaxia said:

"I have signal that change from 1.3 to 1.2k made the 24p lines dissapear.
In other case I have set up the machine with 910 Ohm resistor.

 

Hello Relaxia, may I ask you two questions?

 

1.-Are you saying that depending of the resistance value you get again 24p lines?

2.-Adding resistances with different values is only a temporal solution, sooner or later

    we'll have to reppair or change LCD. isn't it?

 

Thank you,

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Studio01

ad.2  YES - adding the resistors is a temporary solution. If you had "clear" LCD and 24p stripe appears - adding the recommended by KIS 1.3k resistor is giving you 1.5 to 2 years of work. If 24p appears again you can go down with the resistor values. in one case 1.3 to 1.2 worked.

maybe 1.2k to 1k will work as well. in the row we have still 920 and 880, where 880 ohms is IMHO the lowest limit you can afford.

 

Ad.1 NO - I am saying that changing the resistor value you are delaying the necessary LCD replacement time.Depending the machine usage - Each change after the first resistor adding is giving you approximately 6months  to 1year of the work more - before you really need to change the LCD.

the 24p effect will reappear ANYWAY because it is a degradation of the LCD which is processing but applying these changes you can score some time and start to save pennies for LCD replacement.

If you can afford new LCD each 2 years - this is not a topic for you :lol:

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Thank you, Relaxia,

I knew what you are saying but I asked you because, as I know that the only way, at last, is repair

or change LCD, perhaps someone found any trick to not do that.

In 8 years I have changed LCD 4 times!! This change made by official technicians is extremely

expensive, and some little shops like mine can't afford it.

Then, I made an special insurance for machinery, and the 2nd and 3rd LCD was payed by my

insurance company.

And the 4rth one, as I found an external repair service (Alertoff), I took the risk and I'm very happy with

it because, I have 1 year warranty, was fast and cheap (compared to the official). For the moment

half a year and working 100%, and I've made thousand of photos.

I know that my LCD will fail again someday, then I'll connect resistors, and after that repair again

when resistors do nothing.

 

Studio01

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  • 8 months later...

Just to share some valuable new information regarding the newly discovered way to prolong LCD working cycle even if the 24 pixel line start to appear after adding 800 ohm resistance  :) 

 

As we have Kodak System 89 in our office lab, I can experiment on it and as I already had a 1,3k and 800ohm resistor fitted on 3 pins base with middle pin soldered on one pin on the chip and 1,3k soldered with one end on another pin on the chip and another end on one side off this 3 base pin and same thing with 800 ohm resistor but another end is soldered on the third base pin. In that way I had 3 jumper combinations, without resistor (jumper is set free on one pin off that 3 pins base), with 1,3k (jumper set to connect middle and external pin side of that 3 base pins) and with 800 ohm resistor (jumper set on the middle pin and other external side off that 3 base pins).

 

But as 24 line pixel appeared again I done a risky move and connected all 3 pins together and in that way I got 1,3k and 800 ohms resistors connected in parallel connection and in fact it act as 500 ohm resistor and that worked !!!!

 

I had to set flicker to one lower number then previous (from 151 to 150) and that was it  B) 

 

I can not recommend this to all as this 500 ohm resistor was a little bit risky move from my side (I still did not measure the voltage on the LCD to check what is going on), maybe it would be wise to try with 650 ohm resistor, but as I already had this two (1,3k and 800ohm) in place I decided to go with it  :rolleyes: post-1377-0-45492500-1383063004_thumb.jpg

 

Attached image show this multiple resistor setup an that 3 base pin with jumper set to connect one off the two resistors in circuit with this chip on the Epson PCB  ;)​ 
 

And now I connected all three pins together with 3 pin jumper and ended up as one 500 ohm resistor would be connected ;)​  

 

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I guess you have around 21V power supply on the PCB - instead 18,5. YOU WILL COOK the board. 

Friend had installed 800 ohms - and he had to replace whole driver board.

YOu are lucky it still works.

LCD after such treating - is hard to set the polariser, due to power supply change it also shift the colors towards blue. blue spots are appearing on the pictures. it is really hard to set it correctly. I did try... 

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Yes, it still works even after 3 days and 2-3000 prints done  ;)

 

Before this 500 ohm resistor, the 800 ohm resistor was fitted and it worked for year or so, how long will now work this 500 ohm resistor before lines appears again, I do not know, maybe for a year or so  :rolleyes:

 

Few off my colleagues fried the Epson board when they were soldering 1,3k resistor, but it was just because off bad soldering from there side, nothing else, also, my soldering on this board looks very bad, as I was rushing it, but it works  :huh:

 
I fitted 800 ohm resistor on couple off DKS2 and two other colleagues that I know also done it on couple machines without any issue for more then a year now   :)

 

Only issue which appeared after setting the 800 ohm resistor and now this 500 ohm (1,3k + 820 in parallel = about 500 ohm) was that value in Green for polarizing test is bellow both RED and BLUE, but value for RED is higher then for BLUE. Print quality is excellent, I also done Paper Response using the Barbierri Densitometer and even some customers who have DKS3 are impressed with image quality from our office lab System 89  :)

 

But the reason for this lower then it should be value for Green in Polarizer test could be maybe coming from the wash out filters (machine is 10 years old now) in filter disc because off the heat from the lamp ?

Edited by pskaro
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I also added a smaller resistor the the board after the 1.3k from kiss. We tried the conservative option of only 100ohm smaller resistor (added a 10k parallel resistor to the 1.3k and worked like charm.

The only thing we found is that the calibration is a little washed out (lighter).

What we should do to fix that?

Thanks to all

Bruno

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If my calculation is correct, in your case the value ended up as 1.15k, so the difference is 150 ohms, and not 100 ohm  ;)

 

Have you adjusted flicker, checked the gain and LUT Expo curve and adjust if necessary ?

 

I do not have a problems with light paper setup with any resistor combination fitted  :)

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