[Boatanchors] Using an ESR in-circuit Cap meter on a BA

[Garey Barrell]

John -

An ESR meter is only effective on electrolytic (aluminum) capacitors.  
It is a terrific tool for weeding out bad or failing electrolytics 
before you even turn the radio on for the first time.

The meter operates at 100 kHz, so doesn't supply valid information on 
capacitors below about 1 uF.

Bad bypass capacitors can often be spotted by voltage checks (leaky 
cap) or warm caps!  Leaky coupling caps are often spotted by voltage 
checks, pulling the 'receiving' tube and measuring the grid pin 
voltage to ground works.  Some mica 'postage stamp' (red) caps get 
'noisy' from intermittent breakdown, many (brown) ones are bad as they 
are just paper capacitors like the tubular ones.

Best advice is to replace any black plastic with color bands caps 
(bumblebees) or black plastic with printed data (black beauties), or 
those wax covered ones.  Those are bad so often that it doesn't makes 
sense to spend the time checking them.  If you're not convinced, 
remove a few and check them at their working voltage with a Heath or 
EICO or Sprague capacitor tester, with the eye tube for leakage.  They 
must be tested out of circuit, at least one end.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>

John Hensley wrote:
> I'd like to hear from anyone using an ESR in-circuit capacitance evaluator (test meter) when going through a new boat-anchor.  Wholesale recapping seemsto be the default practice but I am curious if anyone has indeed used an ESRmeter to separate out the good & the bad from the ugly ??
> Respond off-list if you'd like.
> TIA
> John
>