[time-nuts] Electrolytic Capacitor Question

Scott McGrath scmcgrath at gmail.com
Mon Nov 10 08:05:19 EST 2014

I've taken a hybrid approach I'm using an in circuit ESR meter to determine whether cap needs to be replaced 

Tantalum capacitors usually fail because of running them too close or at rated voltage.  HP unlike others in the industry did not tend to do this so I've had a low incidence of tantalum caps fail.  Generally the only ones I would replace are ones called out in service notes  or manual updates for uprating in value.

As others have said electrolytics and tantalums look quite different on a network analyzer and HP frequently selected parts for their performance characteristics

As to electrolytics the Panasonics are good but personally I've spent the extra money and used exact replacement Vishay Sprague electrolytics and Tantalums since they were the OEM for most of those parts when gear was built

Sent from my iPhone

> On Nov 8, 2014, at 6:32 PM, Perry Sandeen via time-nuts <time-nuts at febo.com> wrote:
> List,
> OK everybody, let’s not get our pacemakers wound up<G>
> The problem. (Long Intro)
> I have about 15 pieces or so of older HP test equipment.
> 3586B, 5370B, 5335A to name a few.  Because of their age of 20+ years a few have failed and need repair. I
> have decided to go on a wholesale electrolytic capacitor replacement on all of
> them. (Mouser will be able to declare an extra dividend)
> For all the *standard* types I’ve chosen mostly Panasonic
> 105C 10,000 hour caps. So far, so good.
> Now I come to the issue of the wet-slug tantalums that were
> used.  At the time of manufacture, these
> were the best and most expensive low voltage electrolytics available.
> The question is: can one replace the tantalums with the high
> grade (105C) Panasonic or Nichicon capacitors with an equal or higher
> capacitance value?
> Even using the *tear drop* new replacements one is looking
> at very heavy $$$.
> Regards,
> Perrier
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