6550 Users Beware...

[fdegrove]

Hi,

This morning I received an e-mail from Bruce Rozenblit (Transcendent Sound).

Apparently the metal base version of the Svetlana 6550s have this base connected internally to pin # 1 which in turn is connected to pin # 3; the anode/plate.

This obviously exposes any plate voltage present so touching both the base and chassis can present a lethal hazard.

The original mesage can be read here:

MESSAGE BOARD.

Please follow the advise given by Mr. Rozenblit and make sure no plate voltage remains before you pull out the offending tubes.

Cheers,😉

 

[dhaen]

Hi,

Pin 1 should be connected only to the external shield.
I just checked some Sovteks (which are accutely similar to some Svets), and this is the case ( They're OK).
Svetlana 6550 datasheet

I think this can be a warning to us to always ground pin 1 in constructions using 6550's. With this done, there would be no safety hazzard, just a blown fuse.

Cheers,

 

[fdegrove]

Hi,

Thanks, John.

I don't have any 6550Cs handy so I couldn't check.

So, I assume the warning was only sent because on the Transcendent Tube Analyzer octal socket pin #1 and # 3 are tied together.

Cheers,😉

 

[dhaen]

Frank,

That is a thought. The way it's worded, it could be the valves or the analysers that are at fault.

Cheers,

 

[Positron]

6 analyzers

I think you are right. Looks to me like the 6 analyzers are at fault with pins 1 and 3 tied together at the socket.

 

[rdf]

Two year bump. Hi fdegrove, do you use the Transcendent Tube Analyzer? Kindly spare an opinion on it? I caught the bug.

 

[fdegrove]

Hi,

Hi fdegrove, do you use the Transcendent Tube Analyzer?

No, I do not but the problem isn't pertinent to this analysizer.

Cheers,😉

 

[rdf]

It was at the time. TA shipped a half-dozen analyzers with the problem tube. The field repair notification was how I found the thread. Thx for the reply. 🙂