CurtPalme.com Home Theater Forum

[Flemming]

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Dear Forum

Finally, after searching for more than 1 year I got a new blue CRT tube. But when I turn on the projector after installing the new tube the following happens:

1. The new blue tube turn on first.
2. The blue tube get very bright.
3. The projector shuts down (I think this a safety feeature).
4. No light in the green and red tube.

When I disconnect the blue tube again, the green and red turns on normally.

I have attached 5 pictures showing the start up process of the projector until in shut down ... takes totally around 5 sek.

Any ideas ?

Cheers frem Denmark
Flemming

[Curt Palme]

Either the tube is bad, the CRT socket/video amp is bad, or you've bent a pin on the CRT tube when you put the CRT socket on.

[Curt Palme]

Either the tube is bad, the CRT socket/video amp is bad, or you've bent a pin on the CRT tube when you put the CRT socket on.

[Flemming]

Hi Curt

Thank you for the quick respons.

To answer your comments:

I hope the tube is ok ... it was tested before send to me.

I tried using the CRT socket/video amp from my green tube ... same result (and the green work).

I took out the blue tube again and checked the pins ... all look 100% straight (non of them looks bend).

Any other tests I can do? ... or is the only conclusion that the "new" tube is bad?

Thanks again!

[Flemming]

BTW: Could it be the G2 level that needs to be adjusted on the blue tube?

[Curt Palme]

Absolutely not, it is auto adjusting anyway.

[Curt Palme]

Absolutely not, it is auto adjusting anyway.

[Flemming]

Thanks Curt ... based on the above info is there any more tests I can do? ... or what do you think is the must likely problem?

[Curt Palme]

Swap the CRT socket boards between tubes. Check for a bent pin.

[Curt Palme]

Swap the CRT socket boards between tubes. Check for a bent pin.

[Flemming]

Hi Curt

I tried using the CRT socket/video amp from my green tube ... same result (and the green work).

I took out the blue tube again and checked the pins ... all look 100% straight (non of them looks bend).

Any other tests I can do? ... or is the only conclusion that the "new" tube is bad?

[barclay66]

Hi,
I think I have to add some information here as Flemming received the tube from me.
I had this bare blue LUG with minimal wear sitting on a shelf for a few years (intended to be used in my Marquee which never happened). When I purchased this tube I had connected it to my tube analyzer/restorer and checked it. It didn’t show any anomalies (shorts etc.) and I was able to plot its sensitivity which looked nice and normal. So I offered it to him and tested it before mounting it into the Barco housing that Flemming provided.
Testing was done in a Marquee using the Marquee magnetics and a modified neck board (G2 relocation). The tube behaved completely normal and I took some pictures showing a grid and “full white”.
Therefore I cannot explain why it wouldn’t work now.
As mentioned before, Flemming already has swapped the green and blue neck boards and the problem stayed with the blue tube. My recommendation now would be swapping the green with the blue tube. This would rule out either the tube or the chassis.
To my knowledge, the RGB driver board is responsible for generating several signals (apart from the video signals themselves) which are required for the automatic G2 adjustment. There still could be a problem with this board or the chassis which would remain undetected even when swapping the neck boards. First, I had thought it was possible to adjust the G2 level with the menus as it is common for almost any other CRT, but the 909/919 are different. The current problem with the blue looks to me like the G2 level is going through the roof at start up, cathode current rises beyond healthy limits and the protection circuit kicks in and shuts everything down. And we need to find out why this happens.
If there is a problem with the chassis, it even could have been the cause for killing the blue tube in the first place.

[barclay66]

Adding here the measurements for the blue tube in comparison to a green LUG...

[gjaky]

Has anyone verified if the blue neckboard gets G2 voltage at all?

[HaydnG90]

I thought he tried the Blue neckboard on one of the other tubes and it was working fine.

[barclay66]

Yes, but if the neck board doesn’t get all of the voltages/signals it requires it won’t drive the tube correctly even if it’s working fine by itself. That’s what I meant with possible problems with the RGB driver board or the chassis.
I don’t know if Flemming can take voltage measurements so I suggested swapping the tubes in order to rule out either the tube or the chassis.

[Curt Palme]

That would be the next logical step, swap the blue and green tube positions. It's also possible that the electron gun has broken off its mounts. Rare, but I've had it happen 2-3 times over the years.

[Curt Palme]

That would be the next logical step, swap the blue and green tube positions. It's also possible that the electron gun has broken off its mounts. Rare, but I've had it happen 2-3 times over the years.

[Flemming]

Thanks guys for your input.

I will take out the green tube and put it in the blue's position and let you know the result. Will do it later today.

[Flemming]

Hi again

Did some testing:

1. Disconnected the blue tube and took it out of the projector.

2. Disconnected the green tube and then attached all the wires from the green tube to the connections for the blue tube. So now the green tube is connected like it was the blue tube.

3. Turned on the projector ... and now NO picture at all (nothing in the green and nothing in the red ... blue not connected). Same result with and without videosignal connected and no start up Barco picture.

4. Then reconnected the green tube to all its original connectors and now still NO picture (so now in a worse position than when I started).

I notice that it dosent sound like high voltage is supplied to the tubes ... but not sure.

I have attached a picture that shows that now 3 red diodes is turned on (one on the mome HDMI card).

Any ideas?

Thanks for all your help!

Cheers
Flemming

[barclay66]

You have to mount all three tubes with all of their connections (neck boards and magnetics) for the Barco to start correctly. If You want to disable a single tube, disconnect the HV cable only.
So, install the blue tube in the middle (where the green was) and the green on the outside (where the blue was). Leave the HV cable of the green tube unplugged. Then try again.

[Flemming]

Thanks Barclay ... will do.

[Flemming]

I have now swapped the red and the blue tube so that the red now uses all the blue tubes connections (found it easier so swap those two instead of the green and blue).

And now the red tube does what the blue tube did ... it turns on as the only one ... gets bright and the projector shuts down (see attached pic).

Then I disconnected the red tube and turned on the projector with only the green and the new blue tube (in red's place). And the blue tube works perfectly ... so NO problem with the blue tube.

One issue that are making me a little worried. Could I have connected one of the wires for the blue tube wrong? ... especially the 3 connectors with 4-5 pins makes me worry as they can be placed in both directions ... and as it is a long time ago I removed the blue tube I am not 100% sure I remember correctly. I have looked at how the 3 connecters are turned on the green and red tube and done the blue tube the same ... but is this correct? The connectors for the blue tube are not placed the same way (similar order) on the motherboard as the green and red ... so one of the connecters might be turned 180 degrees (see picture 2) ??

All ideas wellcome

Cheers
Flemming

[Curt Palme]

Those are yoke connectors, Worst case, the image ends up being upside down or backwards.

Have you put the blue CRT board onto the green tube?

[Curt Palme]

Those are yoke connectors, Worst case, the image ends up being upside down or backwards.

Have you put the blue CRT board onto the green tube?