Should I replace polymer capacitor?

[chth96]

a few days ago I finally purchased mser-100 v2 and I tested its abillity of measuring ESR value.
I found that It shows pretty accurate ESR value for electrolytic capacitor,But When I measure polymer capacitor of dreamcast game console,I found that one third of polymer capacitor's ESR value is more than twice the value of ESR meter table.(for example, I measured one polymer capacitor of 6.3v 100uf, It showed ESR value of 7.68)
Although my dreamcast now turns 20 years old but it still works. I occasionally have played game with it.
Is this ESR value of polymer capacitor correct?
And should I replace all of polymer capacitor, which exceed the value of ESR meter table, with other good quality electrolytic capacitor? (It is very hard to find good quality polymer capacitor in my country )

[stj]

Re: Should I replace polymer capacitor?

i dont remember the dreamcast using polymers?
any pictures?

[chth96]

Re: Should I replace polymer capacitor?

i dont remember the dreamcast using polymers?
any pictures?

Power supply of dreamcast use electrolytic capacitor.
But mainboard and cd drive of dreamcast use polymers capacitor.

When I measure all electrolytic capacitor, which is located in Power supply of dreamcast, All of Its ESR value is smaller than ESR meter table,But It wasn't when I measure polymers capacitor which is located in mainboard and cd drive

Although,Below link is in japanese, it exactly shows that dreamcast make use of polymers as well as electrolytic capacitor.
https://gamin9ojisan.web.fc2.com/CGC...DCast_001.html

[stj]

Re: Should I replace polymer capacitor?

the esr meter table is useless because it's for general-purpose caps.
you need datasheets for low impedence caps.
the 1800uf caps in the psu are probably not as good as they where.
but are you sure your not mistaking smd electrolytics or tantalum chip caps for polymers?

[stj]

Re: Should I replace polymer capacitor?

https://wiki.console5.com/wiki/Dreamcast

your link only shows one possible polymer - the 220uf one with blue printing

[chth96]

Re: Should I replace polymer capacitor?

the esr meter table is useless because it's for general-purpose caps.
you need datasheets for low impedence caps.
the 1800uf caps in the psu are probably not as good as they where.
but are you sure your not mistaking smd electrolytics or tantalum chip caps for polymers?

I just have realized that I mistake smd electrolytic capacitor for polymers..
It is impossible to find any datasheet of this smd capacitor So I don't know whether it is general-purpose caps or low impedence caps.
By the way,Is it possible to replace smd capacitor with electrolytic capacitor of ultra low impedence caps?

[stj]

Re: Should I replace polymer capacitor?

they may already be low impedence.
dont try replacing them unless they leak - the chance of damaging the pads is high

[chth96]

Re: Should I replace polymer capacitor?

they may already be low impedence.
dont try replacing them unless they leak - the chance of damaging the pads is high

how can I detect leaking smd capercitor?
Is high ESR value enough for detecting leaking or depreciation of capacitor?


I have spare CD drive unit for dreamcast, although It is totally out of order.
I measured its ESR value and I found that ESR value of broken CD drive unit is much higher than working CD drive unit.
for example,when I measure c10 smd capacitor of 6.3v 100uf,it shows 8 ESR value for working unit and 15 for broken unit.
When I measured c509 sms capacitor of 16v 100uf,it shows 11 for working unit and 32 for broken unit.
I think that it is not likely that caps of high ESR value has damaging soldering pads.

[stj]

Re: Should I replace polymer capacitor?

you will see the leak around the contacts
also, if you heat the contact with a soldering iron, electrolyte will smell like cat piss.

[chth96]

Re: Should I replace polymer capacitor?

you will see the leak around the contacts
also, if you heat the contact with a soldering iron, electrolyte will smell like cat piss.

There is no residue around any smd capacitor, and it doesn't smell like any chemical at all.
All of smd capacitor and its solder pads looks very clean.

Judging by comparison with broken CD drive unit, I think that high ESR significantly shows depreciation of capacitor.
Does it have better to replace smd capacitor, which has higher than 10 ESR value, with low impedence& high ripple current electrolytic capacitor?