CurtPalme.com Home Theater Forum

[Squelsh]

Dear Curt
Dear CRT-Community

I bought my self a G70 a year ago. The Tubes are around 2k hours now.

During watching a movie suddenly my green tube stopped working.
No signal, no glowing no sing of life at all.

What I’ve done so far is changing the Neckboards from Red to Green and all I can tell at this point is that’s not the Neckboards. (I couldn’t change the input wires to the Neckboards, because they’re to short to cross-swap)

I searched the web for puzzle pieces of the solution, but I got stuck. What are your further recommendations, possibilities I can go check trough. Could it be the PA Board ? I still not belive it's the tube (I don't like to belive in that

Sorry for my English, it’s not my natural language and I got a lack of technical expressions.

Greetings from Switzerland to the States


Yours faithfully

Dominique

[ecrabb]

Hi Dominique, and welcome to the forum!

Don't worry about your English... It's much better than our German or French!

Curt will be along any time now and can get you back up and running.

SC

[barclay66]

Hi Dominique,

In order to start with something You could check if the tube's heater filament is still intact. Although I've personally never seen a heater filament disintegrate I've heard of such cases. Checking is easy:

- You'll need a Multimeter which can measure continuity and/or resistance between two pins.
- Power Off the G70 and unplug the power cord
- Let the PJ rest for half an hour so that high voltages have degraded
- At the green tube disconnect the wires to its neck board
- Leave the neck board connected to the tube
- On the solder side of the neck board locate the two tube socket pins labeled with an "H"
- Check continuity between those two pins
- If the filament is intact You should measure continuity or a low resistance (below 100 Ohms)
- If You measure an open connection then the tube might be dead

You can see examples of the neck board's solder side here: http://www.curtpalme.com/Sony_G70_Tube_Swap10.shtm

Regards,
barclay66

[CIR Engineering]

Hi,

I would also suggest checking the heater filament, but there is an easier way to get started. Turn on the projector and look inside the tubes near the socket of the red and blue tubes (where the neck cards plug in). You will see the orange glow from the heaters on the red and blue tubes.

The green should have the same glow as the red and blue tubes. If there is no glowing on the green than there is a heater problem and you can go from there.

I think you can get cables from the blue or red tube to reach the green. The best thing is to try this next after heater check. If you absolutely can not get the cables to reach than you can move the blue and green tubes in the G70 and see if green works in the red tube location.

Good luck,
craigr

[barclay66]

Hm, Dominique already stated that he didn't see anything glowing on the green tube...

[draganm]

[Curt Palme]

Do as everyone says above. If there's no glow, then the connection to the filament source from the green tube could be bad, or the green tube itself could be bad. If the green tube faded out, then it could be the tube, if it stopped suddenly without fading out over say 10-20 seconds, then I don't think it's the tube.

It could be a lack of video signal from the RGB board. you can check that by swapping the pairs of mini video connectors between the green and red at the RGB board (pull the wires from the metal connector, if you pull on the black wire, you'll rip the connector off)

It can also be a dead G2 source from the PA board. That's the board under the metal cover under the lenses. There are three single R G and B wires which are the G2 source on that PA board. Swap the R and G, and see if the red tube goes out, and the green comes on.

[Curt Palme]

Do as everyone says above. If there's no glow, then the connection to the filament source from the green tube could be bad, or the green tube itself could be bad. If the green tube faded out, then it could be the tube, if it stopped suddenly without fading out over say 10-20 seconds, then I don't think it's the tube.

It could be a lack of video signal from the RGB board. you can check that by swapping the pairs of mini video connectors between the green and red at the RGB board (pull the wires from the metal connector, if you pull on the black wire, you'll rip the connector off)

It can also be a dead G2 source from the PA board. That's the board under the metal cover under the lenses. There are three single R G and B wires which are the G2 source on that PA board. Swap the R and G, and see if the red tube goes out, and the green comes on.

[Squelsh]

Gentlemen, I appreciate your good advices very much!

Let me summarize what I did so far and to which conclusion I had to come.

First of all, I checked the G2 by swapping the R and G connection wire from the PA-Board,
this seemed to me the most easiest way to start with. The green tube still remained dead.

As mentioned before, I could see no glowing at all (valid point draganm, I wrote this in a too general way - but had the neck board area in mind). Anyway, as Barclay66 and CIR Engeneering suggested, I checked the resistance at the neck board’s solder side. I had no resistance between the two “H” tube socket pins of the green tube. I also removed the neck board from the tube and took measure from the relevant pins directly at the end of the tube (still an open connection). I crosschecked it with the Red tube’s Pin – no surprise there I had the resistance.

@Curt: I cannot tell if it was a fading - or a sudden out of the green tube, because the missing green color was giving the movie scene quite a romantic effect. To be honest I didn’t noticed it for at least two minutes at all.

So a dead tube it is, or is there any chance to fix whatever a heater filament is?


Thank you so much for you help.



Kind Regards


Dominique

[CasetheCorvetteman]

VDC might be able to repair that tube.

[Curt Palme]

\No, if the heater is open, it's toast.

[Curt Palme]

\No, if the heater is open, it's toast.

[CIR Engineering]

Man that really sucks

I would take the tube out and look very carefully at the heater assembly inside the tube just to see it with my own eyes. I doubt it, but you might be able to knock the heater back into place (really really really long shot and won't work but...).

VDC may be able to repair the tube, but isn't there some place in Europe that can also do this?

craigr

[dvh99]

a 2nd hand 8 inch tube with a 8 1/2/ 9 rating isn`t expensive, having the tube repaired at vdc plus shipping will cost more.

there is a company in germany that refurbishes tubes (at least some years ago) but they are not cheap either.

[CasetheCorvetteman]

[dvh99]

sure they can, open the backside, replace the heater extract all oxygen insert nitrogen gas make it vacuum again and melt the glass where you opened the tube so it won`t leak.

a 9rating 2nd hand is his best option.

[Squelsh]

Gentlemen, once again I appreciate your good advices very much!

Sending a tube to VDC or somewhere outside my country to get it fixed, will result in an empty swiss number custody account And to be honest, I’m pretty sure getting this thing back to Switzerland will keep a whole customs-departement busy with finding the duty for a fixed and used CRT-Tube on some lists for a whole week – indeed worth the money.

So I choose the next best option, which was buying a functioning "spare" G70 with acceptable tube condition for 230 Euro on ebay.de (well I haven’t seen them by myself, but the guy wrote R=8, G=7, B=7, should be enough for the next couple of hours, and the supplemental feeling of well sleeping considered having everything twice – except the green tube- is priceless).

So some sort of a happy ending, but let me ask the most important question.

How could this happen, the tube had around 1000 hours and was in a 9-8 condition?

HV arches? A Monday morning in Japan PA Board?

I’m not sure if I should change the tube in my old G70 or go with the new G70 and change the blue and red tube (both 8-9).
What would you guys recomend?

Greetings from the chocolate country

Dominique

[dvh99]

go with the newest chassis and if they are the same age for the pj with the least amount of hours on it.

maybe the heater was damaged a bit in transit who knows.

best to measure the heater voltages, should be 6,3v (not 100% certain though).