[Coco] Fwd: Re: Died from old age?

[Gene Heskett]

On Monday 22 December 2014 11:35:56 Chad H did opine
And Gene did reply:
> -------- Original Message --------
> From: Chad H <chadbh74 at hotmail.com>
> Sent: Monday, December 22, 2014 10:34 AM
> To: ooogalapasooo at aol.com
> Subject: Re: [Coco] Died from old age?
> 
> Well I have a ESR meter so I shouldn't have any problem pulling
> capacitors and testing them. 

Why should you have to pull them?  The only ESR meter I have any 
experience with uses only 85 mv of AC voltage at 100 khz to make its 
measurement with.  This is so low that it does not turn on any parallel 
semiconductors it may be attached to circuit wise, so the caps are checked 
while still in circuit. Because of its time and part saving measurement 
ability when measuring surface mounted caps in DVC-PRO broadcast VCR's, it 
saved me at least 2/3rds of the time to repair and put back in service for 
many of the electronics bits & pieces of a busy TV station for several 
years.

Its called a Capacitor Wizard, and sells for about 2 bills, made in Omaha 
originally but I think the guy has moved to KC sometime it the last 20 
years.  FWIW, caps suffering from ESR are often easily, but temporarily 
fixed, by giving them a charge or discharge at a high enough rate to form 
a micro-weld across the ESR causing aluminum oxide at the internal to 
external terminal connection points.  Quite a few of the other so called 
ESR testers do use enough voltage to "heal the cap", for a day or so.

IMNSHO, this particular device is the only one that measures them all, and 
does it accurately and in circuit. ANYTHING else just wastes your time 
lying to you.

Expensive enough at $200 or so that I do not personally own one, but I 
know where one is that I can use anytime I need it.

> I just don't know about the DIP
> switches.  I also need to identify the thing underneath the crazy heat
> sink.  I think its some sort of power transistor.  Here are pics of
> the board ... tinyurl.com/ko5dxy7.   Still looking for a service
> manual for this model.

That is a more or less std Si, NPN power transistor in a TO-3 case.  Never 
had one fail, but a strong magnifying glass may disclose a micro-crack in 
the solder around the pins on the bottom of the board.  Its cheap solder, 
so suck it or solder-wick it off & replace it with decent, modern silver 
bearing solder.  Use a temp controlled iron, needs 700F to remove that 
junk, but only about 625F to 650F for modern silver bearing solders.  
Rosin core of course.

Lead free solders need more heat. 750F maybe. But I haven't used any of 
that roll I bought with a new soldering iron 2 years ago, and now the iron 
has failed & no help from the american dealer in Lincoln NE, its out of 
warranty and I feel screwed $200 worth.  But guess what? I have a 54 year 
old weller WTC that I pulled off the shelf, and it still works perfectly 
at whatever temp is stamped on the button on the back end of the tip.  Old 
faithful.  Newer ones aren't so good, with fairly rapid heater failures 
when subjected to on in the morning, off whenever the bench lights go off 
for the night duties.  That one worked under such conditions at KOTA-TV 
for several years, and is my emergency goto iron.


Cheers, Gene Heskett
-- 
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Genes Web page <http://geneslinuxbox.net:6309/gene>
US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS