The rectifier from hell, a little story.

[Makofoed-6sn7]

Hello,

I though I would tell you a litte story, about a rectifier that weren't feeling to well.

It all started at work, It came in an beautiful Mesa Dual Rectifier. It weren't feeling to well, it's distortion precense were up and power output down.
Trying to cheer him up as best as I could, I started to debug. First of all the output tubes had low emission. Poping in new ones bought that up, but then the voltage droped. Time for some new rectifiers. I pop'd in two new and slowley bought up the voltage on variac. For some reason the voltage didn't come up, but it didn't pull any current so it was safe to debug with full mains on. Then there was a BANG! Were did that rectifier go? The glas was completley gone. And I was a little bit frighten of the result. The rectifier was bad, popping a new one cured everything, but still...
For some reason, I just have to cover my self when I'm testing something with rectifiers...

Hope I scared some of 'u guys with rect. toobs.

Now, has anyone any ide of what that happend? The getter was fine when I put'd in the amplifier.


Best regards,
Magnus

 

[arnoldc]

That is something I DON'T WANT to experience

 

[kathodyne]

For some reason the voltage didn't come up, but it didn't pull any current so it was safe to debug with full mains on.

that scared me......

strange phenomenon......the voltage didn't come up.....maybe the rectifier was overdissipating way too much, got too hot and imploded?????

 

[Makofoed-6sn7]

Hi,

That's what scared me too. And IF it was overheating, it should have pull'd some current? No heat without current. The anodes was room temprature when I took it out of it's socket, that was very short time after it blowed up.

And I also chek'd the circuit many, many times before plugging in a new after the imploded rectifier. Very, very strange...

So far to my list of nasty thing at work:

Rectifier implosion: Check'd
Amplifier with pig blood: Check'd
Expolding el.cap: Check'd
Man that says that we are "Finnish'd": Check'd

Funny list...

Best regards,
Magnus

 

[Tubelab_com]

I have seen tubes with a hairline crack in the glass shatter with no warning. Sometimes the tube will work normally, other times there will be low current, distortion or other effects of air leaking into the tube. Sometimes there will be a blue or pink glow. Often times the crack will be at the bottom of the tube where the base glass was joined to the bottle. On an octal tube this will be covered up by the plastic base.

I have an 833A that works fine, except for a visible crack. I am afraid to use this tube because it operates at over 1KV. There will be a small nuclear meltdown if that tube shatters under power!

 

[Makofoed-6sn7]

Hi Tubelab,

Could be, if the crack did open when I put it in it's socket. It was a 5U4. Yeah, there was a lot of glass... If I don't remeber worng it take some time for the getter to turn white. I think you are right.
There was a hairline crack that did open when the tubes were put in it's socket. I didn't notice any sign of gas, but i weren't looking to close. If i did, I guess I would have lost some of my sight by now...

Btw, I think we would love some more frightning testing of 833.

Best regards,

Magnus

 

[Tubelab_com]

Btw, I think we would love some more frightning testing of 833.

No time for such fun in the near future, but I have a large box of 833A's. I will build something big when I have some time, and a whole workbench cleaned off.