[Heath] Yet more on my IP-27...

[Mo]

One of the best parts is that the ESR meter will measure in-place
capacitors.  No unsoldering unless it measures defective.

73 de
Mo, AK4RM


> -----Original Message-----
> From: heath-bounces at puck.nether.net 
> [mailto:heath-bounces at puck.nether.net] On Behalf Of Jerry Haigwood
> Sent: Saturday, June 23, 2012 5:27 PM
> To: kgordon2006 at frontier.com
> Cc: Heath at puck.nether.net
> Subject: Re: [Heath] Yet more on my IP-27...
> 
> 
> Ken,
>     There has been considerable discussion of old 
> electrolytic caps and how to determine if they need replacing 
> on another couple of lists I am on.  One of the best ways to 
> determine a bad electrolytic cap is NOT by measuring the 
> value of capacitance but rather measuring the ESR.  The ESR 
> should be only be an ohm or two at most.  Many times an older 
> electrolytic will measure correct capacitance but have an ESR 
> of 10-20 ohms which is bad.  The higher ESR will cause 
> heating and in some cases, an explosion as the electrolyte 
> heats up to the point of causing pressure buildup or physical 
> leakage!  If you don't have an ESR meter, you might consider 
> building or buying one for future repairs.  I know some 
> people who measure the ESR on all the electrolytic caps 
> before they actually start the repair. Jerry W5JH
> 
> -----Original Message-----
> From: heath-bounces at puck.nether.net 
> [mailto:heath-bounces at puck.nether.net]
> On Behalf Of Kenneth G. Gordon
> Sent: Saturday, June 23, 2012 12:55 PM
> To: Ron; Robert Groh
> Cc: Heath at puck.nether.net
> Subject: Re: [Heath] Yet more on my IP-27...
> 
> On 23 Jun 2012 at 8:56, Ron wrote:
> 
> >  > don't leave those old electrolytics in there!
> > 
> > I am not sure I agree. I've restored many, many Heathkit instruments
> > and in just about all, electrolytics that measured OK 
> stayed that way 
> > for a long time. Of course, all electrolytics will go bad 
> *eventually*
> > -- including brand new ones -- but this may happen 20 years 
> later, or
> > 50 years, or tomorrow...
> > 
> > -- Ron
> 
> Well, I suspect from what I have seen in this instrument 
> while restoring it that it had been abused over a long period 
> of time by students at a University teaching lab.
> 
> I am not too surprised at finding bad electroltyics in it.
> 
> However, although I don't routinely replace electrolytics in 
> the equipment I restore, I have found too many bad or leaky 
> or leaking or weak ones to put much faith in them...even when new.
> 
> When I finally replaced all the electrolytics in one of my 
> SB-200s after one failed (rather spectacularly too), all the 
> remaining caps tested at less than 1/2 of their original 
> capacitance: many were down to 1/3 of their original value.
> 
> Ken W7EKB
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