Re: Selenium rectifiers in Tek equipment


stevenhorii
 

Selenium is one of those micro nutrients that you do need. However, it is
also toxic if you get too much. Overheated selenium rectifiers can produce
selenium dioxide which can be toxic if too much is inhaled. If you are
going to power up a piece of equipment with a questionable selenium
rectifier - do it in a place with good ventilation (preferably venting
outside - not to the rest of your workshop or house). This discussion from
the Antique Radio Forums:

https://antiqueradios.com/forums/viewtopic.php?f=6&;t=36453

This suggests being cautious, but not obsessive-compulsive cautious. We
probably get exposed to more lead fumes from soldering than selenium from
bad rectifiers.

On Fri, Feb 5, 2021 at 20:44 Jim Ford <james.ford@cox.net> wrote:

How could they tell; aren't sheep one of the dumbest animals anyway?!

But seriously, I read somewhere that trace amounts of Se are good for
you. Like most things, even water, too much is bad.

Jim Ford

------ Original Message ------
From: "Harvey White" <madyn@dragonworks.info>
To: TekScopes@groups.io
Sent: 2/5/2021 5:20:43 PM
Subject: Re: [TekScopes] Selenium rectifiers in Tek equipment

I remember an old story about sheep eating a certain plant, loco weed,
and having severe congnitive problems.

Turns out that loco weed is high in selenium.

Harvey


On 2/5/2021 7:52 PM, Gary Robert Bosworth wrote:
Good to know.

On Fri, Feb 5, 2021, 16:42 Ken Eckert <eckertkp@gmail.com> wrote:

Burning selenium is very toxic, really bad for your health

On Friday, February 5, 2021, Joe Laffey <joe@thestable.tv> wrote:

If you’ve ever smelled a burned selenium rectifier (stinking up your
office or house for days) you would replace all of them before even
turning
them on.

--
Joe Laffey

On Feb 5, 2021, at 5:24 PM, Dave Wise <david_wise@phoenix.com> wrote:

? Even if the Selenium stacks haven't burned up, by this time their
series resistance is out of spec so the power supplies don't have as
much
mains voltage headroom as they should. I'd replace them without ado
unless
the piece was meant to be a shelf queen.

Dave Wise

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Morris
Odell via groups.io <vilgotch1=gmail.com@groups.io>
Sent: Friday, February 05, 2021 2:29 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Selenium rectifiers in Tek equipment

I have a 127 too and had no compunction in replacing the Se rectifiers
with Si. Nobody can tell you how long it will be before the Se
rectifiers
fail and you will probably always have it in the back of your mind
every
time you switch on the 127. It's not a diffcult or expensive
modification
to do and gives you peace of mind.
I used cheap packaged 1000 volt 1 amp Si bridge rectifiers and
replaced
R601 and R602 with 15 R 3W resistors. I aso inserted a 10R 10W resistor
in
the negative ground connection of the SR603 replacement.
The Si bridges I used had metal cases so I mounted them on insulating
posts, espaciallyu the SR607 replacement which is elevated a few
hundred
volts above the chassis.
Good luck!

Morris


























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