Ms.Pac wet tantalum caps (C5 & C10)

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I checked all caps on my Ms.Pac board with my ESR meter and found C5 and C10 had extremely high ESR values.

I found the caps that I measured being bad looked a bit weird for a normal electrolytic (aluminum) cap. So I checked the schematics of Ms.Pac and found out that they indicate a Tantalum cap at C5 and C10.

When I hear Tantalum I immediately think of these kind of caps:
20071223850263182664.jpg


BUT...the one's I measured wrong didn't look like those at all. Using the power of Google I quickly found out that there are also "wet" Tantalum caps, that look much more like regular electrolytic caps:

Compare, wet tantalum:
Wet_tantalum_capacitor.jpg


and (old fashioned) aluminum electrolytic cap:
R226692-01.jpg


Since these kind of old fashioned "regular" electrolytic caps (GOD I would love everyone used the term Elco for it, like we do in Holland....) were all around the Ms.Pac board I didn't notice the difference...

HOWEVER, the ESR meter can still measure these just as well and so....they _are_ bad.

So I checked for some replacements and almost got a heart-attack:
http://nl.rs-online.com/web/c/?sear...-by=default&sort-order=default&view-type=Grid

Note that these prices are EACH. I guess we're running out of Tantalum ? Should I sell mine to get the Tantalum out of them ?

My _real_ question is....what are the differences between a wet-tantalum (yes, this word sounds dirty) and a regular aluminum elco ?
 
I checked the schematics where cap C5 and C10 are used.

C5 is used across the input of the voltage regulator for the +5V. Instead of a more common 7805, a 78G is used, which can be regulated (contrary to a 7805 which is fixed output). However, the cap seems to perform the basic input filtering of the regulator. Usually you see something like 0,33 uF regular caps there. On data sheets for 7805 they are even indicated to be not necessary if the filter caps behind the rectifiers are physically close to the regulator....
SOooooo, IMHO it is VERY uncritical which type of cap is used here and I have no clue why they chose a wet tantalum ??
I'm sure I'll be fine with a regular elco with the same value there.
(I wonder what effect the high ESR would have had in this application...)

Now for C10:
That one is used in the reset circuit as far as I can see. Doesn't seem to critical either ? Any ideas ?
I think it looks like it's safe enough to use a 10uF regular aluminum cap for both ?
 

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I checked all caps on my Ms.Pac board with my ESR meter and found C5 and C10 had extremely high ESR values.
Unless the component is actually causing a failure, I don't think you should worry about it.

My _real_ question is....what are the differences between a wet-tantalum (yes, this word sounds dirty) and a regular aluminum elco ?
Physical size, frequency response, ESR, availability, price. Tantalums tend to hold their properties with age, but eventually fail by short-circuiting.

SOooooo, IMHO it is VERY uncritical which type of cap is used here and I have no clue why they chose a wet tantalum ??
At the input to a voltage regulator you typically want a capacitor that can react quickly with changes in current. Maybe they selected tantalum because it performs better in this application. Maybe typical electrolytic capacitors were worse back in 1981. This is not a very demanding application so I doubt it will make any difference.
 
Im pretty sure these are standard electrolytics they used on the boards. Even though the schematics call for something doesnt mean thats what they used in production. Even so, I have replaced many many of these with standard electrolytics with no problems.
Also worth mentioning is those 10uf caps always show up questionable with the ESR meter, even new ones. Honestly the only caps on a pac board that I see bad on a regular basis are the 2200 and the 330 used in the sound section.
 
Im pretty sure these are standard electrolytics they used on the boards. Even though the schematics call for something doesnt mean thats what they used in production. Even so, I have replaced many many of these with standard electrolytics with no problems.
Also worth mentioning is those 10uf caps always show up questionable with the ESR meter, even new ones. Honestly the only caps on a pac board that I see bad on a regular basis are the 2200 and the 330 used in the sound section.

Thanks good info, yeah it might as well just be regular aluminum caps, in which case they still did give extremely bad values (check my ESR meter video in another thread) of 66.
I compared it with a brand new "no name" 10uF cap and it had an ESR of 1.27, quite a difference. Still I am even more convinced/confirmed in my decision to replace them with "regular" alu caps (if they weren't already).
 
My girlfriend and I tried the wet-tantalum maneuver the other night and I pulled a muscle in my back.

That's what foreplay is for... helps you stretch and ease into it before you do something that could pull your back out of whack...

Silly man.
 
So I do a flea bay search.
Wow wet Tantalum are expensive..
I thinking I should dig through my cap pile and sell them off. I know I got at least a few hundred of them. It might fund my next arcade buying spree LOL.
 
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