CurtPalme.com Home Theater Forum

[alb_qwerti]

Hi, maybe I've not understand correctly the two test points.

I measured with a multimeter between the core and the mesh of the feedback cable.

A great spark and the HT gone away!

Fortunately re-switching the tubes light up again.

[Hulio]

No, no. You put the positive (red) probe on the core and the negative (black) grounding probe on the metal chassis of the projector.
And do that before starting the projector. You might solder an extension wire from the core solder point.

[alb_qwerti]

OK, I made the test.

The tension rised slowly until 26v and then another spark.
This is a too difficult test with my equipment.

I ask to the forum if someone in Europe have a tested splitter R762718

Thanks,
Alberto

[alb_qwerti]

Hello Hulio,

Now I have another splitter but I think that the last test on the splitter voltage made a big damage.

The green tube does not light on, with the EHT red led.
If I remove the green HT lead from the splitter the set is ok.

How to check for sure if the green tube is shorted?
Is it possible that with the test voltage to measure 34,7 volt finally shorted the tube ?

Thanks,
Alberto

[Hulio]

Hello Alberto,

Hard to say if the spark killed the tube, or the excess of HV ( due to that melted potentiometer on the splitter ).
But indeed, removing a tube's connection with the splitter after a red led on the EHT, if the projector starts up normally with the other two, indicates that the disconnected tube is shorted (or lost his vacuum).
Does the green tube have that orange glow at the end of the neck ?
Without trying the tube in another projector, is hard to say if the tube is shorted. You could try to swap HV inputs on the splitter ( use the "OUT" of red or blue tube ) ?

[alb_qwerti]

Hi,

The end of the tube make a blu spark and than put the EHT on protection mode.
No orange glow on the green tube.
If I change the leads has the same behaviour, always the green is dead.
If I disconnect the lead from the splitter the pj start normally without green.

But what mean exactly a shorted tube? Is dead, not repairable?
What happened inside?
I don't think that it lost his vacuum but probably that spark during the voltage test.

Anuway, is it possible to change the tube on a 1209 hanged on the ceiling?

Thanks.

[Hulio]

Yes, a shorted tube is mostly dead, not to be saved anymore. This because components inside the tube are touching each other, broken or loose. Also a fine crack in the glass will lead to arching.
From all crt projectors models, Barco 9" series have the easiest way of replacing tubes, especially when ceiling mounted. After removing the four bolts that holds the tube in his place (in the front of the projector), the tube is secured by only 2 pins. Pulling down on the tube neck will release the pins from their spring holes.

[virusc]

If you go to replace the tube I would recommend replace with a test CRT of a different color or burned tube in place of the green in case the problem is not resolved and you break another tube. Green is the rarest and most expensive tube to replace unless you happen to have some spares.

[alb_qwerti]

Thanks for your answer.

The problem should has gone.
I replaced the splitter with another one and swapping the HT leads only the green is dead.

Now I open another thread "Shorted Tube" to understand better what's happened.

Thanks,
Alberto