CurtPalme.com Home Theater Forum

[Curt Palme]

OK, here's a new one on me, and I want to make absolutely sure I'm doing the right thing here.

I sold a customer overseas a new old stock set of BG808s tubes. These are the bulletproof Sony tubes that I've never seen fail, save for lack of emission due to 10K hour+ use. In all of the Sony tubes, including the lower end SD and 07 series that I've had here, I cannot ever remember one cracking or imploding.

Customer emailed me a pix of his original tube, the green neck snapped under the main yoke, the same way that NEC XG tubes necks snap when the V deflection fails... the electron beam is bent way out of shape by a V deflection board that goes bad (on the NEC), the electron beam hits the side of the tube neck, and overheats and snaps the tube.

Now, I've NEVER had an issue with a barco V board either, causing tubes to implode. the Barco scan fail automatically shuts down the HV, making a deflection burn due to a bad board almost impossible (from what I've seen).

Now, customer gets said tubes (has been a TV repairman for 30+ years, so he says), and installs them. He now says that the new green tube also has a snapped neck, but instead of shearing completely off, there's a crack/impact point about 5" forward from the CRT socket, around the deflection yoke area. Tube is imploded.

I find it exceptionally strange that two tubes of the same color in a row have imploded. Heck, a runaway HV could also snap a tube neck for that matter, I've had that happen once too.

As per VDC's policy, I don't think I should have to cover this under 'warranty' (not that any was implied), but I always want to take care of my customers. VDC is always adamant that they would not cover burnt phosphor or broken tubes, no matter what the circumstance.

Point is, has anyone ever seen a snapped neck on a Sony/BG808s tube, as I never have.

[Curt Palme]

OK, here's a new one on me, and I want to make absolutely sure I'm doing the right thing here.

I sold a customer overseas a new old stock set of BG808s tubes. These are the bulletproof Sony tubes that I've never seen fail, save for lack of emission due to 10K hour+ use. In all of the Sony tubes, including the lower end SD and 07 series that I've had here, I cannot ever remember one cracking or imploding.

Customer emailed me a pix of his original tube, the green neck snapped under the main yoke, the same way that NEC XG tubes necks snap when the V deflection fails... the electron beam is bent way out of shape by a V deflection board that goes bad (on the NEC), the electron beam hits the side of the tube neck, and overheats and snaps the tube.

Now, I've NEVER had an issue with a barco V board either, causing tubes to implode. the Barco scan fail automatically shuts down the HV, making a deflection burn due to a bad board almost impossible (from what I've seen).

Now, customer gets said tubes (has been a TV repairman for 30+ years, so he says), and installs them. He now says that the new green tube also has a snapped neck, but instead of shearing completely off, there's a crack/impact point about 5" forward from the CRT socket, around the deflection yoke area. Tube is imploded.

I find it exceptionally strange that two tubes of the same color in a row have imploded. Heck, a runaway HV could also snap a tube neck for that matter, I've had that happen once too.

As per VDC's policy, I don't think I should have to cover this under 'warranty' (not that any was implied), but I always want to take care of my customers. VDC is always adamant that they would not cover burnt phosphor or broken tubes, no matter what the circumstance.

Point is, has anyone ever seen a snapped neck on a Sony/BG808s tube, as I never have.

[macgyver655]

Did he run it at all after the tube install? If so how long? Picture normal?

[Curt Palme]

He said 10 minutes. I ran the tube here for 12 hours (at low brightness) and it was fine. I didn't converge, etc, I just had it on top of the set to make sure it focused and had good emission, but I ran it overnight.

[Curt Palme]

He said 10 minutes. I ran the tube here for 12 hours (at low brightness) and it was fine. I didn't converge, etc, I just had it on top of the set to make sure it focused and had good emission, but I ran it overnight.

[macgyver655]

Your deflection yolk or his?

His 10 minutes normal image?

[Curt Palme]

His set, he's in Europe. He claims it was running fine. to complicate things a bit, dad doesn't speak English, so his non technical son is the go-between.

[Curt Palme]

His set, he's in Europe. He claims it was running fine. to complicate things a bit, dad doesn't speak English, so his non technical son is the go-between.

[km987654]

Are there any identifying marks on the tubes? Just to confirm they are the same tubes that is.

[macgyver655]

I know everyone always hates to ask... but did he tighten the yolk clamp to tight?

[Curt Palme]

ya know, that's a good point.. that's about where the puncture was. I can't post the pix, he embedded it into his email, and I can't extract it.

[Curt Palme]

ya know, that's a good point.. that's about where the puncture was. I can't post the pix, he embedded it into his email, and I can't extract it.

[macgyver655]

If you have win 7 you can snip out the image.

Or forward me the email.

[macgyver655]

Tube pics:

[gjaky]

Ha, no way that was done by electron beam... There electron still travels in the metal cylinder (G2 maybe?), and is not even that fast at that point.

[Curt Palme]

So how did it happen? Mac suggested maybe something was stuck under a yoke clamp, putting pressure on the tube, or just over-tightening of the yoke clamp?

[Curt Palme]

So how did it happen? Mac suggested maybe something was stuck under a yoke clamp, putting pressure on the tube, or just over-tightening of the yoke clamp?

[gjaky]

[Curt Palme]

I agree, a fault in the tube doesn't make sense. I did once implode a BArco 708 tube which is similar to these, but I forgot to connect the HV regulator connector (small 2 pin connector) which caused the HV to exceeed 40Kv. the tube arced internally and cracked, but at the point where the tube neck flares up to the front of the tube.

I would say that this is physical pressure on the tube neck. I am linking the customer to this thread so he can see other opinions, but from what you and Mac are saying, this cannot be caused by the tube itself, which is what I say as well.

[Curt Palme]

I agree, a fault in the tube doesn't make sense. I did once implode a BArco 708 tube which is similar to these, but I forgot to connect the HV regulator connector (small 2 pin connector) which caused the HV to exceeed 40Kv. the tube arced internally and cracked, but at the point where the tube neck flares up to the front of the tube.

I would say that this is physical pressure on the tube neck. I am linking the customer to this thread so he can see other opinions, but from what you and Mac are saying, this cannot be caused by the tube itself, which is what I say as well.

[Curt Palme]

Also, looking at the pix again, the crack point is more under the EM focusing yoke assembly, not the deflection yoke. I agree then that the electron beam cannot be deflected that much to cause it to hit the side of the neck.

[Curt Palme]

Also, looking at the pix again, the crack point is more under the EM focusing yoke assembly, not the deflection yoke. I agree then that the electron beam cannot be deflected that much to cause it to hit the side of the neck.

[Ile]

Crack seem to bee at focus yoke clamp area.

There is also neck board support clamp, but it's bit further back.

Yoke clamps have grounding cable to neck board. Don't think leaving it unconnected would cause any harm, I guess grounding is just to make yoke adjustment more friendly.

[Tom.W]

[km987654]

[macgyver655]

Or it did not crack until the thermal property changed. As tube warmed up it would expand. I usually barely snug those clamp sometimes thinking they are to loose.