CurtPalme.com Home Theater Forum

SGIforever · Joined: 06 Jul 2009 Posts: 66 Location: Sweden

Hi,

I'm still messing around with my ancient Barco Data PC (R9000280), just for the fun of it.

I suddenly have a very bright blue tube, much brighter than the others even when grey scale adjustment is turned down as far as it can.
I might have broken something when I adjusted the tube angles to align R/B.
When the machine was turned of, I removed to check something on the SMPS board and then I put i back in again. I didn't notice that the
blue tube had moved a little (the screws wasn't fastened) and a SMPS heatsink came in touch with the neckboard (maybe a resistor on
the neckboard).
I turned on the machine again and noticed a brighter blue. Turned it off and found the problem. I moved the tube, but still bright blue tube.

Is there another trimpot to turn down the brightness of the blue? Is the tube or neckboard gone?
At far as I recall the testgrid on the blue tube was better before.

Pictures have been arranged to show the situation (with power off Smile

).

barclay66 · Posted: Tue Apr 17, 2012 4:20 pm Post subject:

Hi,

looks like a bad neck board or bad RGB amplifier to me.

For the neck board You could try the following:

- Swap the neck boards between the green and blue tube
- If now the green tube is brighter then it's the neck board
- If the blue tube stays bright then it might be the tube itself or the RGB output board

I wouldn't try adjusting anything as it was well adjusted before the damage. Fiddling with the controls will most likely create more problems than solving them...

Regards,
barclay66

HaydnG90 · Joined: 22 May 2006 Posts: 1356

Have you adjusted the G2

SGIforever · Joined: 06 Jul 2009 Posts: 66 Location: Sweden

Thank you for quick response.

I will try the neckboard swap. I might have spare RGB amplifier to try as well.

I did try some trimpots for horisontal adjustments, in case the blue picture was shifted to much left or right
and I was seing backtrace (if that's what it is called).
I checked their position before I turned them and tried to set them back to where they were. By the way it
was the trimpots on the 'control panel', not the ones on the boards you need a screwdriver to turn.

I thought the greyscale adjustment has to do with G2. If not - where can I look for it?

barclay66 · Posted: Tue Apr 17, 2012 5:06 pm Post subject:

SGIforever · Joined: 06 Jul 2009 Posts: 66 Location: Sweden

I've been on the old analog Barco page. Actually, I think I was the one who contributed with the BD PC service manual Smile

Reading the schematics it seems like the G2 are in fact the greyscale adjustment pots.
I checked tha RGB board by switching the small B and G outgoing wires. The problem moved to the green tube so that concludes where the problem is. Thank you.

I have 761160 and 761168, but I don't think they are compatible, at least that is what I get from the schematics.
Anybody with an extra 20-year old Barco RGB board no 761365 Smile

It is possible my local tv-repair guy can solve the problem. Any ideas what to check on the RGB board?

/Bjorn

**Curt Palme** · Posted: Wed Apr 18, 2012 6:52 pm Post subject:

Your G2s are adjusted on the convergence board, see your first picture. Check the voltage coming off those leads, all three tubes should have about the same voltage on them, +/- 50-100 volts or so. If the blue is high by 200 volts or so, I'd check the resistors around those controls, or maybe the control opened up?

barclay66 · Posted: Wed Apr 18, 2012 9:05 pm Post subject:

**Curt Palme** · Posted: Thu Apr 19, 2012 1:34 am Post subject:

Oops, sorry, didn't read that...as usual.

BTW, are you sure that flywire (blue) in the 4th picture isn't a G2 wire? Is it the main video feed? (it's been probably 10 years since I worked on a Data projector, so I really can't remember).

SGIforever · Joined: 06 Jul 2009 Posts: 66 Location: Sweden

I include a slightly zoomed out picture where you can follow the blue wire to the RGB board.

On the image of the crt socket board I think the G2 is in 'connector E' and not in the 'to decoder' (blue wire).
So blue wire is probably video feed.

barclay66 · Posted: Thu Apr 19, 2012 6:58 pm Post subject:

Yes, You're right!
The G2 supply is on the connector that goes to the frame. So the single colored cable is the tube's cathode connector which goes into the RGB board. Maybe a close visual inspection could already reveal something on its blue channel...

Regards,
barclay66

**Curt Palme** · Posted: Thu Apr 19, 2012 10:50 pm Post subject:

Right, you're right! That's how they did it on the 600 and 400 as well, I should have remembered!

So yes, check the video board like you said before.