Tant PS caps

[bruno2000]

Can someone tell me why in older gear, major manufacturers used tant caps as ps bypass caps?  I have just spend several hours finding ONE shorted cap among MANY in an old analog pc board.  I suppose I should just rip them all out and replace with modern low ESR?
Thanks for your comments!
Best,
Bruno2000

 

[radardoug]

Tants have low ESR and were used in old gear for this. Unfortunately they dont like voltage spikes. So they do often fail in old gear.
There are modern electrolytics which will perform as well. With the advent of switchmode supplies, low ESR caps became much more common.

 

[hymentoptera]

I've found more than 1 shorted tantalum cap in old PSUs, most recently an old Urei 562 notch filter. It killed the vreg it was strapped across, but otherwise no serious damage. This time. Replaced with new Kemet tant, PSU is good as new, but I suppose if ESR is a concern you could parallel several aluminum electrolytics that add up to same or more capacitance if there's room.

 

[gyraf]

I have a feeling that tantalums in power supply lines was only industrially done for a short time in the mid-80'es before everyone realized the problem in the error-mode.

And then again to be repeated for different reasons in late-90'es consumer goods, when there was a period where tantalums were the only cheap large-value caps in some SMD formats

Jakob E.

 

[Gold]

The Neumann VG66  lathe amplifier rack used tantalum rail bypass capacitors.  The VG66 was made from the the late 1960's  through the early 1970's.

You  could get more capacitance in a smaller package. A 47uF tantalum was a lot smaller than an axial 47uF aluminum electrolytic.  A modern radial aluminum electrolytic is about the same size as a comparable tantalum.

 

[abbey road d enfer]

Can someone tell me why in older gear, major manufacturers used tant caps as ps bypass caps?  I have just spend several hours finding ONE shorted cap among MANY in an old analog pc board.  I suppose I should just rip them all out and replace with modern low ESR?
Thanks for your comments!
Best,
Bruno2000

It's just an example of something that looked like a good idea at the time...Ford Edsel, Chevy Corvair, quadrophony, Betamax...

 

[mjrippe]

Another famous case is the Neve 54 series.  Tantalum power coupling everywhere and when they fail short they take out the current limit resistors as well.