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Discussion Starter · #1 ·
I have a Barco Data 808 and attempted to do the G2

adjustment last night.


When I initiated the G2 adjust mode from the service menu,

I opened the baby up and found that the LEDs were lit

for the red and blue CRTs. THis was the first time I tried this

adjustment, but was able to find the G2 potentiometers OK.

A slow turn of the red potentiometer made that LED go out,

but I turned the blue potentiometer through it's full range

and its LED stayed on.


It seems that turning the potentiometer counter-clockwise

turns the CRT off, and clockwise increases its intensity. I ended

up turning it most of the way up, but backed it off from a

fully clockwise setting for safety sake.


The color balance looks decent to my naive eyes now, but

I'm wondering what all this means about the condition of

my projector.


Does anyone know what this G2 adjustment problem means

in terms of the projector's condition and longevity?


Thanks for you inpu.


Rick
 

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I think you have mis-understood a little the process of G2 adjustment on the 808... First of all, you have been tweaking the G2 itself, not the potentiometer that should be turned in order to shut down the LEDs. The G2 should be set at the same level on all tubes, and then you should turn the LED potentiometer until the LIDs go off. DO NOT TURN THE WRONG POTENTIOMETER, as I did! Be sure not to turn the RGB potentiometer, but the one stating G2 LED or something (both behind the neck of the tubes). The G2 is located in the back of the unit with the other cards...(just to make sure it is not the RBG, but the G2 you have been tweaking....)
 

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Discussion Starter · #3 ·
The adjustments I made were using 3 small plastic discs with

an X pattern cut into them so they can be rotated with

a screwdriver. They are mounted right together on one

of the circuit boards in the back of the 808. I think they were

on the 2nd card from the right when looking from the back

of the chassis.


I was going by a copy of the manual and it had a picture to

help locate them. Unfortunately, my copy of the picture is not

clear, but it looked like the right location and this was the

only set of 3 adjustments that I could see. One is marked with

red ink, one blue, and one green. When I turned the red one

and the LED behind the red CRT went out, I figured these

were the G2 potentiometers. Is this correct?


Rick
 

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Hello Guy's


Don't change the pot from the green led this adjustment is only done when you mount a new set of tubes and calibrate the G2

You only need to turn the pots you described with red green and bleu dots on the G2 diagnostic board until the green led is of


Rick how many hours did your projector run it's possible that your blue tube is done and have to be replaced or rebuild

Also if you do the adjustment rotate the pot very slow see if that helps

If you put up a total white field is it white or a little yellow


Rob
 

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Discussion Starter · #7 ·
Hi Rob,


The projector has about 3500 hours on it. I don't know how

much of this time may have been in standby. I recently

bought it and understand it was taken out of a corporate

meeting room.


Before I tried to adjust G2, the colors looked washed out

to me. Now if anything they may be oversaturated. Reds

and blues are more vivid. It looks better to me now than it

did, though.


A white screen does look white

to me. If anything it may be a bit blueish, but not yellowish.


Perhaps I should back the blue potentiometer down a bit more.


I'd like to determine if there is something really wrong with the projector, because I think it is still returnable.


Rick
 

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Hello Rick


Back of bleu it should look a bit reddish

Rotate the G2 bleu knob real slow maybe the led goes out

I think there is nothing wrong sometimes it's difficult to get the led off


Rob
 

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Hi,


I have a Barco 1208 and the G2 adjustments are in the same location. It took several times with my blue tube turning the pot VERY VERY slowly to find the spot where the LED goes out. It was hard to find!


I can verify the adjustment it is very sensitve but able to be done.


Jeff
 

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Discussion Starter · #12 ·
I did the G2 admustment procedure again on the blue CRT,

this time very, very, slowly. However, the LED stays on

throughout the range of motion of the potentiometer.


I did the adjustment by moving the potentiometer the smallest

amount I could and then pausing a few seconds. I went through

the whole range of the control that way and no change in the

LED at all. The blue level looks correct at nearly full clockwise,

so that's where I left it.


There may be a fault in the circuit that drives the LED. Oh, well..


Rick
 

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If you are not able to get the lid off within the range of the G2 setting, you can probably tweak the potentiometer behind the neck of the tube a little. As long as all the tubes have the same amount of power, this is really not a problem! Turn it just a little bit, and I'm sure your lid will go off in a second! It's the pot. on the left when viewing from front. As long as you don't adjust the other potentiometers on the board, I don't think this is a problematic procedure...
 

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Discussion Starter · #15 ·
Jon,


I want to make sure I understand which pot you

are talking about. I think you mean the pot on the

circuit board mounted horizontally (parallel to the

top of the case) behind the neck of the blue CRT.

There are 2 pots next to each other on that board,

labeled P1 and P2. I turned the one on the left (looking

from the front of the projector) a little clockwise.


This did not change the G2 adjustment situation. The

LED still will not go off. Before I try turning this pot any

more I just wanted to check that I have the right one.


Thanks for your help,


Rick
 

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Romano,


If you are talking about the BarcoGraphics 1209s and not the 1209, then the reference level for G2 is set by going into the MENU - SERVICE - G2 ADJUSTMENTS and you adjust the 3 pots located on the board all the way to the side in the back of the projector next to the power supply. I have just received a full service manual for the 1209s so if you have questions I can see what I can help you with.


Per Johnny Ødegaard
 
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