Howdy, from Wyoming

[Spencer Allen]

Reminds me of a switching power supply I used to work on for a high  
PRF laser.  It had, among other things, 8 TO-3 switching transistors  
in one leg.

When one of these failed it would take out the other 7.  The failure  
itself was spectacular.  The emitter leads were missing.  The wire to  
the emitter lead was still intact including the solder joint - but no  
emitter lead.  The glass seal in the bottom of the TO-3 where the  
emitter lead used to be was sealed shut.  here was a hole in the top  
of the TO-3 above where the emitter lead should have been.  We never  
could find the emitter lead so we never knew if it had been ejected  
at high velocity or just evaporated.  (I guess I really mean  
sublimated since it would have gone fro solid to vapor.)

We were using some expensive Delco transistors in the power supply.   
We ran out and Delco quit making them.  We replaced them with some  
generic el-cheapo horizontal fly-back transistors and never had  
another failure.

We also invented the SEC (Smoke Emitting Capacitor) and the FER  
(Flame Emitting Resistor).

Anyone remember the spec sheet National Semiconductor put out for the  
Write-Only Memory?

Mike, K4JEM

"Not everything that counts can be counted and not everything that can
be counted counts."

     Albert Einstein.





On Aug 24, 2006, at 12:41 PM, TChesek at Epix.Net wrote:

> Doc,
>
> Now you've opened the door for electrolytic stories. I two short  
> tales to
> tell. When I first went to my local community college, 37 years  
> ago, there
> were several pictures posted beside the chalk board. One picture  
> was very
> interesting and none of us could figure out what it was until we  
> asked the
> instructor. He said that a previous student connected an  
> electrolytic with
> the wrong polarity and what we saw in the picture was the top of  
> the metal
> can embedded in a ceiling tile. A good picture for a poignant  
> lesson. The
> second tale is when I was working for Varityper repairing a failed  
> power
> supply in a phototypesetter. It was our experience that the externally
> mounted electrolytic was the cause of supply failures so on repeat  
> power
> supply replacement we swapped out the cap. It was located in the  
> bottom of
> the cabinet with no light and I reversed the leads by mistake.  
> After a few
> short minutes this loud hiss and terrible stench permeated the  
> room. The
> owner asked what happened and I told him that occasionally we get a  
> bad
> batch of parts. hi hi.
>
> Tom K3TVC
>
> ----- Original Message -----
> From: "kd4e" <kd4e at VERIZON.NET>
> To: <HEATH at LISTSERV.TEMPE.GOV>
> Sent: Wednesday, August 23, 2006 8:58 PM
> Subject: Re: [HEATH-TEMPE] Howdy, from Wyoming
>
>


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