Secondary light emanating through the top support in 6HB5?

[Disco-Pete]

So these reside in an Acoustat Servo Charge OTL. On standby, the filaments are lit up as normally, slight glow. I'm seeing tiny specs of white light poking through the mica support at the top. They are bright but very tiny. I have 3 other amps just like it in the same system. It's only happening in one. Does anyone know what this is? TIA

 

[Suncalc]

A picture would help if you can get one.

 

[Disco-Pete]

Could a mod please correct the title? They're 6hb5, not 6nb5.
My bad. Thanks

 

[rayma]

Title fixed.

 

[vinylkid58]

I'm seeing tiny specs of white light poking through the mica support at the top. They are bright but very tiny.

Any idea what the plate voltage is? Just curious, as I have a similar tube (6JM6) in my DCPP amp. I'm going to fire it up tonight with the lights out.

jeff

 

[Disco-Pete]

Don't know.

 

[Disco-Pete]

The white specs at bottom right of three tubes is the light I'm referring to. There could be up to 4 on each tube intermittently appearing/disappearing. It's difficult to capture through the cage but I cant' turn on the amp without the cage installed.

 

[Osvaldo de Banfield]

Are you sure that tubes glass isn't reflecting lights from a pilot lamp or led?

 

[Disco-Pete]

There are no LEDs or other light sources. It's definitely coming through the mica support inside the tube.

Umm, on second thought, when I close the front door they disappear. It's the light coming through the front door of the house reflecting on the tubes. Sorry folks!

Thanks Osvaldo

 

[Refugee1]

Well done.
It looks like a daylight reflection off the mica supports.

 

[Osvaldo de Banfield]

But mica are opaque. More probable that reflecting surface be the glass envelope.

 

[Refugee1]

I was thinking of those little rods that run through the anode and are pinched into a little blade to keep the mica on.
If they are made of bright metal they may well glint in light that is coming from the side.

 

[vinylkid58]

It's difficult to capture through the cage but I cant' turn on the amp without the cage installed.

Safely first.

jeff

 

[Disco-Pete]

It appeared the light was coming through small holes in the mica but alas, the convex shape of the glass reduces the reflected image's size. The interesting thing is they appear on four corners simultaneously.

I should point out it is my WIFE who pointed this out to me. She was afraid the amp will blow up and burn the house down.

 

[JMFahey]

Are you sure that tubes glass isn't reflecting lights from a pilot lamp or led?

👍🏻👍🏻👍🏻

 

[Disco-Pete]

Yes, this time I'm sure. Closing the front door or putting my hand between the cage and the door makes them disappear.

 

[vinylkid58]

I should point out it is my WIFE who pointed this out to me. She was afraid the amp will blow up and burn the house down.

Tell her the fuses will blow before it catches fire.

jeff