General advice on replacement of old decoupling tantalum capacitors (by new tants or alum. lytics).

Fabio Trevisan

Hi Folks,
Apologies for bringing this subject up again, but on searching for the
subject on Tekscopes, it's so prevalent that I found hard to spot a thread
that actually answers my question.

A couple of days ago I powered up my Tek 464 and it wouldn't show a trace
and started smelling.
Checked low voltage power supplies and +15V was dead.
Found a 15uF color coded tantalum capacitor (blob type) blackened and dead
I replaced that one and luckily nothing else was damaged and scope got back
Before the same starts happening to others and end up actually damaging
something, I decided to look for replacing all those tantalum caps, or at
least all the ones that are connected directly to power rails for

So, here comes my question... In recapping those 40yo scopes and plugins,
what is the general advice?
1. To recap using new tantalum capacitors and just derate the new ones by a
fair amount, say, +50% or more to avoid their dreaded failure mode?
2. Forget tants altogether and replace them by new aluminum electrolytic
capacitors (wherever physical size allow).

Thanks for sharing your wisdom.



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